其实很多时候，我们并不需要去重复造轮子，只需要借 就可以。但是前提就得你得知道谁家有轮子可借才行。这次就用到了 org.apache.common.io 家的轮子了。
具体实现：
public String downloadHttpUrl(String url, String dir) {
String fileName = "test.jpg";
try {
URL httpurl = new URL(url);
File f = new File(dir + fileName);
FileUtils.copyURLToFile(httpurl, f);
} catch (Exception e) {
e.printStackTrace();
return "";
}
return dir + fileName;
}
上文中用到的 FileUtils 来源于： org.apache.commons.io.FileUtils 。那么问题又来了 他是怎么实现的呢，接着往下看源码FileUtils.clsss
public static void copyURLToFile(URL source, File destination) throws IOException {
InputStream input = source.openStream();
try {
FileOutputStream output = openOutputStream(destination);
try {
IOUtils.copy(input, output);
} finally {
IOUtils.closeQuietly(output);
}
} finally {
IOUtils.closeQuietly(input);
}
}
继续： IOUtils.copy 具体干了哪些活呢
public static int copy(InputStream input, OutputStream output) throws IOException {
long count = copyLarge(input, output);
if (count > Integer.MAX_VALUE) {
return -1;
}
return (int) count;
}
copylarge
public static long copyLarge(InputStream input, OutputStream output)
throws IOException {
byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
long count = 0;
int n = 0;
while (-1 != (n = input.read(buffer))) {
output.write(buffer, 0, n);
count += n;
}
return count;
}
哦哦哦，原来如此， 无非也是 InputStream 到 OutputStream 的 过程。 现在反过来想想，如果没有借助此轮子，自己去造是不是思路也一样用到 InputStream 和 OutputStream 。 既然人家已经有了就要学会拿来用。
这样一来，通过一个下载 我们就学习了两个轮子 org.apache.commons.io.FileUtils 和 org.apache.commons.io.IOUtils .
引申学习：这里面封装好了很多我们平时经常用的方法，为日常编码带来很多方便。
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.io;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;
import java.util.zip.Checksum;
import org.apache.commons.io.filefilter.DirectoryFileFilter;
import org.apache.commons.io.filefilter.FalseFileFilter;
import org.apache.commons.io.filefilter.FileFilterUtils;
import org.apache.commons.io.filefilter.IOFileFilter;
import org.apache.commons.io.filefilter.SuffixFileFilter;
import org.apache.commons.io.filefilter.TrueFileFilter;
import org.apache.commons.io.output.NullOutputStream;
/**
* General file manipulation utilities.
* <p>
* Facilities are provided in the following areas:
* <ul>
* <li>writing to a file
* <li>reading from a file
* <li>make a directory including parent directories
* <li>copying files and directories
* <li>deleting files and directories
* <li>converting to and from a URL
* <li>listing files and directories by filter and extension
* <li>comparing file content
* <li>file last changed date
* <li>calculating a checksum
* </ul>
* <p>
* Origin of code: Excalibur, Alexandria, Commons-Utils
*
* @author <a href="mailto:[email protected]">Kevin A. Burton</A>
* @author <a href="mailto:[email protected]">Scott Sanders</a>
* @author <a href="mailto:[email protected]">Daniel Rall</a>
* @author <a href="mailto:[email protected]">Christoph.Reck</a>
* @author <a href="mailto:[email protected]">Peter Donald</a>
* @author <a href="mailto:[email protected]">Jeff Turner</a>
* @author Matthew Hawthorne
* @author <a href="mailto:[email protected]">Jeremias Maerki</a>
* @author Stephen Colebourne
* @author Ian Springer
* @author Chris Eldredge
* @author Jim Harrington
* @author Niall Pemberton
* @author Sandy McArthur
* @version $Id: FileUtils.java 507684 2007-02-14 20:38:25Z bayard $
*/
public class FileUtils {
/**
* Instances should NOT be constructed in standard programming.
*/
public FileUtils() {
super();
}
/**
* The number of bytes in a kilobyte.
*/
public static final long ONE_KB = 1024;
/**
* The number of bytes in a megabyte.
*/
public static final long ONE_MB = ONE_KB * ONE_KB;
/**
* The number of bytes in a gigabyte.
*/
public static final long ONE_GB = ONE_KB * ONE_MB;
/**
* An empty array of type <code>File</code>.
*/
public static final File[] EMPTY_FILE_ARRAY = new File[0];
//-----------------------------------------------------------------------
/**
* Opens a {@link FileInputStream} for the specified file, providing better
* error messages than simply calling <code>new FileInputStream(file)</code>.
* <p>
* At the end of the method either the stream will be successfully opened,
* or an exception will have been thrown.
* <p>
* An exception is thrown if the file does not exist.
* An exception is thrown if the file object exists but is a directory.
* An exception is thrown if the file exists but cannot be read.
*
* @param file the file to open for input, must not be <code>null</code>
* @return a new {@link FileInputStream} for the specified file
* @throws FileNotFoundException if the file does not exist
* @throws IOException if the file object is a directory
* @throws IOException if the file cannot be read
* @since Commons IO 1.3
*/
public static FileInputStream openInputStream(File file) throws IOException {
if (file.exists()) {
if (file.isDirectory()) {
throw new IOException("File '" + file + "' exists but is a directory");
}
if (file.canRead() == false) {
throw new IOException("File '" + file + "' cannot be read");
}
} else {
throw new FileNotFoundException("File '" + file + "' does not exist");
}
return new FileInputStream(file);
}
//-----------------------------------------------------------------------
/**
* Opens a {@link FileOutputStream} for the specified file, checking and
* creating the parent directory if it does not exist.
* <p>
* At the end of the method either the stream will be successfully opened,
* or an exception will have been thrown.
* <p>
* The parent directory will be created if it does not exist.
* The file will be created if it does not exist.
* An exception is thrown if the file object exists but is a directory.
* An exception is thrown if the file exists but cannot be written to.
* An exception is thrown if the parent directory cannot be created.
*
* @param file the file to open for output, must not be <code>null</code>
* @return a new {@link FileOutputStream} for the specified file
* @throws IOException if the file object is a directory
* @throws IOException if the file cannot be written to
* @throws IOException if a parent directory needs creating but that fails
* @since Commons IO 1.3
*/
public static FileOutputStream openOutputStream(File file) throws IOException {
if (file.exists()) {
if (file.isDirectory()) {
throw new IOException("File '" + file + "' exists but is a directory");
}
if (file.canWrite() == false) {
throw new IOException("File '" + file + "' cannot be written to");
}
} else {
File parent = file.getParentFile();
if (parent != null && parent.exists() == false) {
if (parent.mkdirs() == false) {
throw new IOException("File '" + file + "' could not be created");
}
}
}
return new FileOutputStream(file);
}
//-----------------------------------------------------------------------
/**
* Returns a human-readable version of the file size, where the input
* represents a specific number of bytes.
*
* @param size the number of bytes
* @return a human-readable display value (includes units)
*/
public static String byteCountToDisplaySize(long size) {
String displaySize;
if (size / ONE_GB > 0) {
displaySize = String.valueOf(size / ONE_GB) + " GB";
} else if (size / ONE_MB > 0) {
displaySize = String.valueOf(size / ONE_MB) + " MB";
} else if (size / ONE_KB > 0) {
displaySize = String.valueOf(size / ONE_KB) + " KB";
} else {
displaySize = String.valueOf(size) + " bytes";
}
return displaySize;
}
//-----------------------------------------------------------------------
/**
* Implements the same behaviour as the "touch" utility on Unix. It creates
* a new file with size 0 or, if the file exists already, it is opened and
* closed without modifying it, but updating the file date and time.
* <p>
* NOTE: As from v1.3, this method throws an IOException if the last
* modified date of the file cannot be set. Also, as from v1.3 this method
* creates parent directories if they do not exist.
*
* @param file the File to touch
* @throws IOException If an I/O problem occurs
*/
public static void touch(File file) throws IOException {
if (!file.exists()) {
OutputStream out = openOutputStream(file);
IOUtils.closeQuietly(out);
}
boolean success = file.setLastModified(System.currentTimeMillis());
if (!success) {
throw new IOException("Unable to set the last modification time for " + file);
}
}
//-----------------------------------------------------------------------
/**
* Converts a Collection containing java.io.File instanced into array
* representation. This is to account for the difference between
* File.listFiles() and FileUtils.listFiles().
*
* @param files a Collection containing java.io.File instances
* @return an array of java.io.File
*/
public static File[] convertFileCollectionToFileArray(Collection files) {
return (File[]) files.toArray(new File[files.size()]);
}
//-----------------------------------------------------------------------
/**
* Finds files within a given directory (and optionally its
* subdirectories). All files found are filtered by an IOFileFilter.
*
* @param files the collection of files found.
* @param directory the directory to search in.
* @param filter the filter to apply to files and directories.
*/
private static void innerListFiles(Collection files, File directory,
IOFileFilter filter) {
File[] found = directory.listFiles((FileFilter) filter);
if (found != null) {
for (int i = 0; i < found.length; i++) {
if (found[i].isDirectory()) {
innerListFiles(files, found[i], filter);
} else {
files.add(found[i]);
}
}
}
}
/**
* Finds files within a given directory (and optionally its
* subdirectories). All files found are filtered by an IOFileFilter.
* <p>
* If your search should recurse into subdirectories you can pass in
* an IOFileFilter for directories. You don't need to bind a
* DirectoryFileFilter (via logical AND) to this filter. This method does
* that for you.
* <p>
* An example: If you want to search through all directories called
* "temp" you pass in <code>FileFilterUtils.NameFileFilter("temp")</code>
* <p>
* Another common usage of this method is find files in a directory
* tree but ignoring the directories generated CVS. You can simply pass
* in <code>FileFilterUtils.makeCVSAware(null)</code>.
*
* @param directory the directory to search in
* @param fileFilter filter to apply when finding files.
* @param dirFilter optional filter to apply when finding subdirectories.
* If this parameter is <code>null</code>, subdirectories will not be included in the
* search. Use TrueFileFilter.INSTANCE to match all directories.
* @return an collection of java.io.File with the matching files
* @see org.apache.commons.io.filefilter.FileFilterUtils
* @see org.apache.commons.io.filefilter.NameFileFilter
*/
public static Collection listFiles(
File directory, IOFileFilter fileFilter, IOFileFilter dirFilter) {
if (!directory.isDirectory()) {
throw new IllegalArgumentException(
"Parameter 'directory' is not a directory");
}
if (fileFilter == null) {
throw new NullPointerException("Parameter 'fileFilter' is null");
}
//Setup effective file filter
IOFileFilter effFileFilter = FileFilterUtils.andFileFilter(fileFilter,
FileFilterUtils.notFileFilter(DirectoryFileFilter.INSTANCE));
//Setup effective directory filter
IOFileFilter effDirFilter;
if (dirFilter == null) {
effDirFilter = FalseFileFilter.INSTANCE;
} else {
effDirFilter = FileFilterUtils.andFileFilter(dirFilter,
DirectoryFileFilter.INSTANCE);
}
//Find files
Collection files = new java.util.LinkedList();
innerListFiles(files, directory,
FileFilterUtils.orFileFilter(effFileFilter, effDirFilter));
return files;
}
/**
* Allows iteration over the files in given directory (and optionally
* its subdirectories).
* <p>
* All files found are filtered by an IOFileFilter. This method is
* based on {@link #listFiles(File, IOFileFilter, IOFileFilter)}.
*
* @param directory the directory to search in
* @param fileFilter filter to apply when finding files.
* @param dirFilter optional filter to apply when finding subdirectories.
* If this parameter is <code>null</code>, subdirectories will not be included in the
* search. Use TrueFileFilter.INSTANCE to match all directories.
* @return an iterator of java.io.File for the matching files
* @see org.apache.commons.io.filefilter.FileFilterUtils
* @see org.apache.commons.io.filefilter.NameFileFilter
* @since Commons IO 1.2
*/
public static Iterator iterateFiles(
File directory, IOFileFilter fileFilter, IOFileFilter dirFilter) {
return listFiles(directory, fileFilter, dirFilter).iterator();
}
//-----------------------------------------------------------------------
/**
* Converts an array of file extensions to suffixes for use
* with IOFileFilters.
*
* @param extensions an array of extensions. Format: {"java", "xml"}
* @return an array of suffixes. Format: {".java", ".xml"}
*/
private static String[] toSuffixes(String[] extensions) {
String[] suffixes = new String[extensions.length];
for (int i = 0; i < extensions.length; i++) {
suffixes[i] = "." + extensions[i];
}
return suffixes;
}
/**
* Finds files within a given directory (and optionally its subdirectories)
* which match an array of extensions.
*
* @param directory the directory to search in
* @param extensions an array of extensions, ex. {"java","xml"}. If this
* parameter is <code>null</code>, all files are returned.
* @param recursive if true all subdirectories are searched as well
* @return an collection of java.io.File with the matching files
*/
public static Collection listFiles(
File directory, String[] extensions, boolean recursive) {
IOFileFilter filter;
if (extensions == null) {
filter = TrueFileFilter.INSTANCE;
} else {
String[] suffixes = toSuffixes(extensions);
filter = new SuffixFileFilter(suffixes);
}
return listFiles(directory, filter,
(recursive ? TrueFileFilter.INSTANCE : FalseFileFilter.INSTANCE));
}
/**
* Allows iteration over the files in a given directory (and optionally
* its subdirectories) which match an array of extensions. This method
* is based on {@link #listFiles(File, String[], boolean)}.
*
* @param directory the directory to search in
* @param extensions an array of extensions, ex. {"java","xml"}. If this
* parameter is <code>null</code>, all files are returned.
* @param recursive if true all subdirectories are searched as well
* @return an iterator of java.io.File with the matching files
* @since Commons IO 1.2
*/
public static Iterator iterateFiles(
File directory, String[] extensions, boolean recursive) {
return listFiles(directory, extensions, recursive).iterator();
}
//-----------------------------------------------------------------------
/**
* Compare the contents of two files to determine if they are equal or not.
* <p>
* This method checks to see if the two files are different lengths
* or if they point to the same file, before resorting to byte-by-byte
* comparison of the contents.
* <p>
* Code origin: Avalon
*
* @param file1 the first file
* @param file2 the second file
* @return true if the content of the files are equal or they both don't
* exist, false otherwise
* @throws IOException in case of an I/O error
*/
public static boolean contentEquals(File file1, File file2) throws IOException {
boolean file1Exists = file1.exists();
if (file1Exists != file2.exists()) {
return false;
}
if (!file1Exists) {
// two not existing files are equal
return true;
}
if (file1.isDirectory() || file2.isDirectory()) {
// don't want to compare directory contents
throw new IOException("Can't compare directories, only files");
}
if (file1.length() != file2.length()) {
// lengths differ, cannot be equal
return false;
}
if (file1.getCanonicalFile().equals(file2.getCanonicalFile())) {
// same file
return true;
}
InputStream input1 = null;
InputStream input2 = null;
try {
input1 = new FileInputStream(file1);
input2 = new FileInputStream(file2);
return IOUtils.contentEquals(input1, input2);
} finally {
IOUtils.closeQuietly(input1);
IOUtils.closeQuietly(input2);
}
}
//-----------------------------------------------------------------------
/**
* Convert from a <code>URL</code> to a <code>File</code>.
* <p>
* From version 1.1 this method will decode the URL.
* Syntax such as <code>file:///my%20docs/file.txt</code> will be
* correctly decoded to <code>/my docs/file.txt</code>.
*
* @param url the file URL to convert, <code>null</code> returns <code>null</code>
* @return the equivalent <code>File</code> object, or <code>null</code>
* if the URL's protocol is not <code>file</code>
* @throws IllegalArgumentException if the file is incorrectly encoded
*/
public static File toFile(URL url) {
if (url == null || !url.getProtocol().equals("file")) {
return null;
} else {
String filename = url.getFile().replace('/', File.separatorChar);
int pos =0;
while ((pos = filename.indexOf('%', pos)) >= 0) {
if (pos + 2 < filename.length()) {
String hexStr = filename.substring(pos + 1, pos + 3);
char ch = (char) Integer.parseInt(hexStr, 16);
filename = filename.substring(0, pos) + ch + filename.substring(pos + 3);
}
}
return new File(filename);
}
}
/**
* Converts each of an array of <code>URL</code> to a <code>File</code>.
* <p>
* Returns an array of the same size as the input.
* If the input is <code>null</code>, an empty array is returned.
* If the input contains <code>null</code>, the output array contains <code>null</code> at the same
* index.
* <p>
* This method will decode the URL.
* Syntax such as <code>file:///my%20docs/file.txt</code> will be
* correctly decoded to <code>/my docs/file.txt</code>.
*
* @param urls the file URLs to convert, <code>null</code> returns empty array
* @return a non-<code>null</code> array of Files matching the input, with a <code>null</code> item
* if there was a <code>null</code> at that index in the input array
* @throws IllegalArgumentException if any file is not a URL file
* @throws IllegalArgumentException if any file is incorrectly encoded
* @since Commons IO 1.1
*/
public static File[] toFiles(URL[] urls) {
if (urls == null || urls.length == 0) {
return EMPTY_FILE_ARRAY;
}
File[] files = new File[urls.length];
for (int i = 0; i < urls.length; i++) {
URL url = urls[i];
if (url != null) {
if (url.getProtocol().equals("file") == false) {
throw new IllegalArgumentException(
"URL could not be converted to a File: " + url);
}
files[i] = toFile(url);
}
}
return files;
}
/**
* Converts each of an array of <code>File</code> to a <code>URL</code>.
* <p>
* Returns an array of the same size as the input.
*
* @param files the files to convert
* @return an array of URLs matching the input
* @throws IOException if a file cannot be converted
*/
public static URL[] toURLs(File[] files) throws IOException {
URL[] urls = new URL[files.length];
for (int i = 0; i < urls.length; i++) {
urls[i] = files[i].toURL();
}
return urls;
}
//-----------------------------------------------------------------------
/**
* Copies a file to a directory preserving the file date.
* <p>
* This method copies the contents of the specified source file
* to a file of the same name in the specified destination directory.
* The destination directory is created if it does not exist.
* If the destination file exists, then this method will overwrite it.
*
* @param srcFile an existing file to copy, must not be <code>null</code>
* @param destDir the directory to place the copy in, must not be <code>null</code>
*
* @throws NullPointerException if source or destination is null
* @throws IOException if source or destination is invalid
* @throws IOException if an IO error occurs during copying
* @see #copyFile(File, File, boolean)
*/
public static void copyFileToDirectory(File srcFile, File destDir) throws IOException {
copyFileToDirectory(srcFile, destDir, true);
}
/**
* Copies a file to a directory optionally preserving the file date.
* <p>
* This method copies the contents of the specified source file
* to a file of the same name in the specified destination directory.
* The destination directory is created if it does not exist.
* If the destination file exists, then this method will overwrite it.
*
* @param srcFile an existing file to copy, must not be <code>null</code>
* @param destDir the directory to place the copy in, must not be <code>null</code>
* @param preserveFileDate true if the file date of the copy
* should be the same as the original
*
* @throws NullPointerException if source or destination is <code>null</code>
* @throws IOException if source or destination is invalid
* @throws IOException if an IO error occurs during copying
* @see #copyFile(File, File, boolean)
* @since Commons IO 1.3
*/
public static void copyFileToDirectory(File srcFile, File destDir, boolean preserveFileDate) throws IOException {
if (destDir == null) {
throw new NullPointerException("Destination must not be null");
}
if (destDir.exists() && destDir.isDirectory() == false) {
throw new IllegalArgumentException("Destination '" + destDir + "' is not a directory");
}
copyFile(srcFile, new File(destDir, srcFile.getName()), preserveFileDate);
}
/**
* Copies a file to a new location preserving the file date.
* <p>
* This method copies the contents of the specified source file to the
* specified destination file. The directory holding the destination file is
* created if it does not exist. If the destination file exists, then this
* method will overwrite it.
*
* @param srcFile an existing file to copy, must not be <code>null</code>
* @param destFile the new file, must not be <code>null</code>
*
* @throws NullPointerException if source or destination is <code>null</code>
* @throws IOException if source or destination is invalid
* @throws IOException if an IO error occurs during copying
* @see #copyFileToDirectory(File, File)
*/
public static void copyFile(File srcFile, File destFile) throws IOException {
copyFile(srcFile, destFile, true);
}
/**
* Copies a file to a new location.
* <p>
* This method copies the contents of the specified source file
* to the specified destination file.
* The directory holding the destination file is created if it does not exist.
* If the destination file exists, then this method will overwrite it.
*
* @param srcFile an existing file to copy, must not be <code>null</code>
* @param destFile the new file, must not be <code>null</code>
* @param preserveFileDate true if the file date of the copy
* should be the same as the original
*
* @throws NullPointerException if source or destination is <code>null</code>
* @throws IOException if source or destination is invalid
* @throws IOException if an IO error occurs during copying
* @see #copyFileToDirectory(File, File, boolean)
*/
public static void copyFile(File srcFile, File destFile,
boolean preserveFileDate) throws IOException {
if (srcFile == null) {
throw new NullPointerException("Source must not be null");
}
if (destFile == null) {
throw new NullPointerException("Destination must not be null");
}
if (srcFile.exists() == false) {
throw new FileNotFoundException("Source '" + srcFile + "' does not exist");
}
if (srcFile.isDirectory()) {
throw new IOException("Source '" + srcFile + "' exists but is a directory");
}
if (srcFile.getCanonicalPath().equals(destFile.getCanonicalPath())) {
throw new IOException("Source '" + srcFile + "' and destination '" + destFile + "' are the same");
}
if (destFile.getParentFile() != null && destFile.getParentFile().exists() == false) {
if (destFile.getParentFile().mkdirs() == false) {
throw new IOException("Destination '" + destFile + "' directory cannot be created");
}
}
if (destFile.exists() && destFile.canWrite() == false) {
throw new IOException("Destination '" + destFile + "' exists but is read-only");
}
doCopyFile(srcFile, destFile, preserveFileDate);
}
/**
* Internal copy file method.
*
* @param srcFile the validated source file, must not be <code>null</code>
* @param destFile the validated destination file, must not be <code>null</code>
* @param preserveFileDate whether to preserve the file date
* @throws IOException if an error occurs
*/
private static void doCopyFile(File srcFile, File destFile, boolean preserveFileDate) throws IOException {
if (destFile.exists() && destFile.isDirectory()) {
throw new IOException("Destination '" + destFile + "' exists but is a directory");
}
FileInputStream input = new FileInputStream(srcFile);
try {
FileOutputStream output = new FileOutputStream(destFile);
try {
IOUtils.copy(input, output);
} finally {
IOUtils.closeQuietly(output);
}
} finally {
IOUtils.closeQuietly(input);
}
if (srcFile.length() != destFile.length()) {
throw new IOException("Failed to copy full contents from '" +
srcFile + "' to '" + destFile + "'");
}
if (preserveFileDate) {
destFile.setLastModified(srcFile.lastModified());
}
}
//-----------------------------------------------------------------------
/**
* Copies a directory to within another directory preserving the file dates.
* <p>
* This method copies the source directory and all its contents to a
* directory of the same name in the specified destination directory.
* <p>
* The destination directory is created if it does not exist.
* If the destination directory did exist, then this method merges
* the source with the destination, with the source taking precedence.
*
* @param srcDir an existing directory to copy, must not be <code>null</code>
* @param destDir the directory to place the copy in, must not be <code>null</code>
*
* @throws NullPointerException if source or destination is <code>null</code>
* @throws IOException if source or destination is invalid
* @throws IOException if an IO error occurs during copying
* @since Commons IO 1.2
*/
public static void copyDirectoryToDirectory(File srcDir, File destDir) throws IOException {
if (srcDir == null) {
throw new NullPointerException("Source must not be null");
}
if (srcDir.exists() && srcDir.isDirectory() == false) {
throw new IllegalArgumentException("Source '" + destDir + "' is not a directory");
}
if (destDir == null) {
throw new NullPointerException("Destination must not be null");
}
if (destDir.exists() && destDir.isDirectory() == false) {
throw new IllegalArgumentException("Destination '" + destDir + "' is not a directory");
}
copyDirectory(srcDir, new File(destDir, srcDir.getName()), true);
}
/**
* Copies a whole directory to a new location preserving the file dates.
* <p>
* This method copies the specified directory and all its child
* directories and files to the specified destination.
* The destination is the new location and name of the directory.
* <p>
* The destination directory is created if it does not exist.
* If the destination directory did exist, then this method merges
* the source with the destination, with the source taking precedence.
*
* @param srcDir an existing directory to copy, must not be <code>null</code>
* @param destDir the new directory, must not be <code>null</code>
*
* @throws NullPointerException if source or destination is <code>null</code>
* @throws IOException if source or destination is invalid
* @throws IOException if an IO error occurs during copying
* @since Commons IO 1.1
*/
public static void copyDirectory(File srcDir, File destDir) throws IOException {
copyDirectory(srcDir, destDir, true);
}
/**
* Copies a whole directory to a new location.
* <p>
* This method copies the contents of the specified source directory
* to within the specified destination directory.
* <p>
* The destination directory is created if it does not exist.
* If the destination directory did exist, then this method merges
* the source with the destination, with the source taking precedence.
*
* @param srcDir an existing directory to copy, must not be <code>null</code>
* @param destDir the new directory, must not be <code>null</code>
* @param preserveFileDate true if the file date of the copy
* should be the same as the original
*
* @throws NullPointerException if source or destination is <code>null</code>
* @throws IOException if source or destination is invalid
* @throws IOException if an IO error occurs during copying
* @since Commons IO 1.1
*/
public static void copyDirectory(File srcDir, File destDir,
boolean preserveFileDate) throws IOException {
if (srcDir == null) {
throw new NullPointerException("Source must not be null");
}
if (destDir == null) {
throw new NullPointerException("Destination must not be null");
}
if (srcDir.exists() == false) {
throw new FileNotFoundException("Source '" + srcDir + "' does not exist");
}
if (srcDir.isDirectory() == false) {
throw new IOException("Source '" + srcDir + "' exists but is not a directory");
}
if (srcDir.getCanonicalPath().equals(destDir.getCanonicalPath())) {
throw new IOException("Source '" + srcDir + "' and destination '" + destDir + "' are the same");
}
doCopyDirectory(srcDir, destDir, preserveFileDate);
}
/**
* Internal copy directory method.
*
* @param srcDir the validated source directory, must not be <code>null</code>
* @param destDir the validated destination directory, must not be <code>null</code>
* @param preserveFileDate whether to preserve the file date
* @throws IOException if an error occurs
* @since Commons IO 1.1
*/
private static void doCopyDirectory(File srcDir, File destDir, boolean preserveFileDate) throws IOException {
if (destDir.exists()) {
if (destDir.isDirectory() == false) {
throw new IOException("Destination '" + destDir + "' exists but is not a directory");
}
} else {
if (destDir.mkdirs() == false) {
throw new IOException("Destination '" + destDir + "' directory cannot be created");
}
if (preserveFileDate) {
destDir.setLastModified(srcDir.lastModified());
}
}
if (destDir.canWrite() == false) {
throw new IOException("Destination '" + destDir + "' cannot be written to");
}
// recurse
File[] files = srcDir.listFiles();
if (files == null) { // null if security restricted
throw new IOException("Failed to list contents of " + srcDir);
}
for (int i = 0; i < files.length; i++) {
File copiedFile = new File(destDir, files[i].getName());
if (files[i].isDirectory()) {
doCopyDirectory(files[i], copiedFile, preserveFileDate);
} else {
doCopyFile(files[i], copiedFile, preserveFileDate);
}
}
}
//-----------------------------------------------------------------------
/**
* Copies bytes from the URL <code>source</code> to a file
* <code>destination</code>. The directories up to <code>destination</code>
* will be created if they don't already exist. <code>destination</code>
* will be overwritten if it already exists.
*
* @param source the <code>URL</code> to copy bytes from, must not be <code>null</code>
* @param destination the non-directory <code>File</code> to write bytes to
* (possibly overwriting), must not be <code>null</code>
* @throws IOException if <code>source</code> URL cannot be opened
* @throws IOException if <code>destination</code> is a directory
* @throws IOException if <code>destination</code> cannot be written
* @throws IOException if <code>destination</code> needs creating but can't be
* @throws IOException if an IO error occurs during copying
*/
public static void copyURLToFile(URL source, File destination) throws IOException {
InputStream input = source.openStream();
try {
FileOutputStream output = openOutputStream(destination);
try {
IOUtils.copy(input, output);
} finally {
IOUtils.closeQuietly(output);
}
} finally {
IOUtils.closeQuietly(input);
}
}
//-----------------------------------------------------------------------
/**
* Recursively delete a directory.
*
* @param directory directory to delete
* @throws IOException in case deletion is unsuccessful
*/
public static void deleteDirectory(File directory) throws IOException {
if (!directory.exists()) {
return;
}
cleanDirectory(directory);
if (!directory.delete()) {
String message =
"Unable to delete directory " + directory + ".";
throw new IOException(message);
}
}
/**
* Clean a directory without deleting it.
*
* @param directory directory to clean
* @throws IOException in case cleaning is unsuccessful
*/
public static void cleanDirectory(File directory) throws IOException {
if (!directory.exists()) {
String message = directory + " does not exist";
throw new IllegalArgumentException(message);
}
if (!directory.isDirectory()) {
String message = directory + " is not a directory";
throw new IllegalArgumentException(message);
}
File[] files = directory.listFiles();
if (files == null) { // null if security restricted
throw new IOException("Failed to list contents of " + directory);
}
IOException exception = null;
for (int i = 0; i < files.length; i++) {
File file = files[i];
try {
forceDelete(file);
} catch (IOException ioe) {
exception = ioe;
}
}
if (null != exception) {
throw exception;
}
}
//-----------------------------------------------------------------------
/**
* Waits for NFS to propagate a file creation, imposing a timeout.
* <p>
* This method repeatedly tests {@link File#exists()} until it returns
* true up to the maximum time specified in seconds.
*
* @param file the file to check, must not be <code>null</code>
* @param seconds the maximum time in seconds to wait
* @return true if file exists
* @throws NullPointerException if the file is <code>null</code>
*/
public static boolean waitFor(File file, int seconds) {
int timeout = 0;
int tick = 0;
while (!file.exists()) {
if (tick++ >= 10) {
tick = 0;
if (timeout++ > seconds) {
return false;
}
}
try {
Thread.sleep(100);
} catch (InterruptedException ignore) {
// ignore exception
} catch (Exception ex) {
break;
}
}
return true;
}
//-----------------------------------------------------------------------
/**
* Reads the contents of a file into a String.
* The file is always closed.
*
* @param file the file to read, must not be <code>null</code>
* @param encoding the encoding to use, <code>null</code> means platform default
* @return the file contents, never <code>null</code>
* @throws IOException in case of an I/O error
* @throws java.io.UnsupportedEncodingException if the encoding is not supported by the VM
*/
public static String readFileToString(File file, String encoding) throws IOException {
InputStream in = null;
try {
in = openInputStream(file);
return IOUtils.toString(in, encoding);
} finally {
IOUtils.closeQuietly(in);
}
}
/**
* Reads the contents of a file into a String using the default encoding for the VM.
* The file is always closed.
*
* @param file the file to read, must not be <code>null</code>
* @return the file contents, never <code>null</code>
* @throws IOException in case of an I/O error
* @since Commons IO 1.3.1
*/
public static String readFileToString(File file) throws IOException {
return readFileToString(file, null);
}
/**
* Reads the contents of a file into a byte array.
* The file is always closed.
*
* @param file the file to read, must not be <code>null</code>
* @return the file contents, never <code>null</code>
* @throws IOException in case of an I/O error
* @since Commons IO 1.1
*/
public static byte[] readFileToByteArray(File file) throws IOException {
InputStream in = null;
try {
in = openInputStream(file);
return IOUtils.toByteArray(in);
} finally {
IOUtils.closeQuietly(in);
}
}
/**
* Reads the contents of a file line by line to a List of Strings.
* The file is always closed.
*
* @param file the file to read, must not be <code>null</code>
* @param encoding the encoding to use, <code>null</code> means platform default
* @return the list of Strings representing each line in the file, never <code>null</code>
* @throws IOException in case of an I/O error
* @throws java.io.UnsupportedEncodingException if the encoding is not supported by the VM
* @since Commons IO 1.1
*/
public static List readLines(File file, String encoding) throws IOException {
InputStream in = null;
try {
in = openInputStream(file);
return IOUtils.readLines(in, encoding);
} finally {
IOUtils.closeQuietly(in);
}
}
/**
* Reads the contents of a file line by line to a List of Strings using the default encoding for the VM.
* The file is always closed.
*
* @param file the file to read, must not be <code>null</code>
* @return the list of Strings representing each line in the file, never <code>null</code>
* @throws IOException in case of an I/O error
* @since Commons IO 1.3
*/
public static List readLines(File file) throws IOException {
return readLines(file, null);
}
/**
* Return an Iterator for the lines in a <code>File</code>.
* <p>
* This method opens an <code>InputStream</code> for the file.
* When you have finished with the iterator you should close the stream
* to free internal resources. This can be done by calling the
* {@link LineIterator#close()} or
* {@link LineIterator#closeQuietly(LineIterator)} method.
* <p>
* The recommended usage pattern is:
* <pre>
* LineIterator it = FileUtils.lineIterator(file, "UTF-8");
* try {
* while (it.hasNext()) {
* String line = it.nextLine();
* /// do something with line
* }
* } finally {
* LineIterator.closeQuietly(iterator);
* }
* </pre>
* <p>
* If an exception occurs during the creation of the iterator, the
* underlying stream is closed.
*
* @param file the file to open for input, must not be <code>null</code>
* @param encoding the encoding to use, <code>null</code> means platform default
* @return an Iterator of the lines in the file, never <code>null</code>
* @throws IOException in case of an I/O error (file closed)
* @since Commons IO 1.2
*/
public static LineIterator lineIterator(File file, String encoding) throws IOException {
InputStream in = null;
try {
in = openInputStream(file);
return IOUtils.lineIterator(in, encoding);
} catch (IOException ex) {
IOUtils.closeQuietly(in);
throw ex;
} catch (RuntimeException ex) {
IOUtils.closeQuietly(in);
throw ex;
}
}
/**
* Return an Iterator for the lines in a <code>File</code> using the default encoding for the VM.
*
* @param file the file to open for input, must not be <code>null</code>
* @return an Iterator of the lines in the file, never <code>null</code>
* @throws IOException in case of an I/O error (file closed)
* @since Commons IO 1.3
* @see #lineIterator(File, String)
*/
public static LineIterator lineIterator(File file) throws IOException {
return lineIterator(file, null);
}
//-----------------------------------------------------------------------
/**
* Writes a String to a file creating the file if it does not exist.
*
* NOTE: As from v1.3, the parent directories of the file will be created
* if they do not exist.
*
* @param file the file to write
* @param data the content to write to the file
* @param encoding the encoding to use, <code>null</code> means platform default
* @throws IOException in case of an I/O error
* @throws java.io.UnsupportedEncodingException if the encoding is not supported by the VM
*/
public static void writeStringToFile(File file, String data, String encoding) throws IOException {
OutputStream out = null;
try {
out = openOutputStream(file);
IOUtils.write(data, out, encoding);
} finally {
IOUtils.closeQuietly(out);
}
}
/**
* Writes a String to a file creating the file if it does not exist using the default encoding for the VM.
*
* @param file the file to write
* @param data the content to write to the file
* @throws IOException in case of an I/O error
*/
public static void writeStringToFile(File file, String data) throws IOException {
writeStringToFile(file, data, null);
}
/**
* Writes a byte array to a file creating the file if it does not exist.
* <p>
* NOTE: As from v1.3, the parent directories of the file will be created
* if they do not exist.
*
* @param file the file to write to
* @param data the content to write to the file
* @throws IOException in case of an I/O error
* @since Commons IO 1.1
*/
public static void writeByteArrayToFile(File file, byte[] data) throws IOException {
OutputStream out = null;
try {
out = openOutputStream(file);
out.write(data);
} finally {
IOUtils.closeQuietly(out);
}
}
/**
* Writes the <code>toString()</code> value of each item in a collection to
* the specified <code>File</code> line by line.
* The specified character encoding and the default line ending will be used.
* <p>
* NOTE: As from v1.3, the parent directories of the file will be created
* if they do not exist.
*
* @param file the file to write to
* @param encoding the encoding to use, <code>null</code> means platform default
* @param lines the lines to write, <code>null</code> entries produce blank lines
* @throws IOException in case of an I/O error
* @throws java.io.UnsupportedEncodingException if the encoding is not supported by the VM
* @since Commons IO 1.1
*/
public static void writeLines(File file, String encoding, Collection lines) throws IOException {
writeLines(file, encoding, lines, null);
}
/**
* Writes the <code>toString()</code> value of each item in a collection to
* the specified <code>File</code> line by line.
* The default VM encoding and the default line ending will be used.
*
* @param file the file to write to
* @param lines the lines to write, <code>null</code> entries produce blank lines
* @throws IOException in case of an I/O error
* @since Commons IO 1.3
*/
public static void writeLines(File file, Collection lines) throws IOException {
writeLines(file, null, lines, null);
}
/**
* Writes the <code>toString()</code> value of each item in a collection to
* the specified <code>File</code> line by line.
* The specified character encoding and the line ending will be used.
* <p>
* NOTE: As from v1.3, the parent directories of the file will be created
* if they do not exist.
*
* @param file the file to write to
* @param encoding the encoding to use, <code>null</code> means platform default
* @param lines the lines to write, <code>null</code> entries produce blank lines
* @param lineEnding the line separator to use, <code>null</code> is system default
* @throws IOException in case of an I/O error
* @throws java.io.UnsupportedEncodingException if the encoding is not supported by the VM
* @since Commons IO 1.1
*/
public static void writeLines(File file, String encoding, Collection lines, String lineEnding) throws IOException {
OutputStream out = null;
try {
out = openOutputStream(file);
IOUtils.writeLines(lines, lineEnding, out, encoding);
} finally {
IOUtils.closeQuietly(out);
}
}
/**
* Writes the <code>toString()</code> value of each item in a collection to
* the specified <code>File</code> line by line.
* The default VM encoding and the specified line ending will be used.
*
* @param file the file to write to
* @param lines the lines to write, <code>null</code> entries produce blank lines
* @param lineEnding the line separator to use, <code>null</code> is system default
* @throws IOException in case of an I/O error
* @since Commons IO 1.3
*/
public static void writeLines(File file, Collection lines, String lineEnding) throws IOException {
writeLines(file, null, lines, lineEnding);
}
//-----------------------------------------------------------------------
/**
* Delete a file. If file is a directory, delete it and all sub-directories.
* <p>
* The difference between File.delete() and this method are:
* <ul>
* <li>A directory to be deleted does not have to be empty.</li>
* <li>You get exceptions when a file or directory cannot be deleted.
* (java.io.File methods returns a boolean)</li>
* </ul>
*
* @param file file or directory to delete, must not be <code>null</code>
* @throws NullPointerException if the directory is <code>null</code>
* @throws IOException in case deletion is unsuccessful
*/
public static void forceDelete(File file) throws IOException {
if (file.isDirectory()) {
deleteDirectory(file);
} else {
if (!file.exists()) {
throw new FileNotFoundException("File does not exist: " + file);
}
if (!file.delete()) {
String message =
"Unable to delete file: " + file;
throw new IOException(message);
}
}
}
/**
* Schedule a file to be deleted when JVM exits.
* If file is directory delete it and all sub-directories.
*
* @param file file or directory to delete, must not be <code>null</code>
* @throws NullPointerException if the file is <code>null</code>
* @throws IOException in case deletion is unsuccessful
*/
public static void forceDeleteOnExit(File file) throws IOException {
if (file.isDirectory()) {
deleteDirectoryOnExit(file);
} else {
file.deleteOnExit();
}
}
/**
* Recursively schedule directory for deletion on JVM exit.
*
* @param directory directory to delete, must not be <code>null</code>
* @throws NullPointerException if the directory is <code>null</code>
* @throws IOException in case deletion is unsuccessful
*/
private static void deleteDirectoryOnExit(File directory) throws IOException {
if (!directory.exists()) {
return;
}
cleanDirectoryOnExit(directory);
directory.deleteOnExit();
}
/**
* Clean a directory without deleting it.
*
* @param directory directory to clean, must not be <code>null</code>
* @throws NullPointerException if the directory is <code>null</code>
* @throws IOException in case cleaning is unsuccessful
*/
private static void cleanDirectoryOnExit(File directory) throws IOException {
if (!directory.exists()) {
String message = directory + " does not exist";
throw new IllegalArgumentException(message);
}
if (!directory.isDirectory()) {
String message = directory + " is not a directory";
throw new IllegalArgumentException(message);
}
File[] files = directory.listFiles();
if (files == null) { // null if security restricted
throw new IOException("Failed to list contents of " + directory);
}
IOException exception = null;
for (int i = 0; i < files.length; i++) {
File file = files[i];
try {
forceDeleteOnExit(file);
} catch (IOException ioe) {
exception = ioe;
}
}
if (null != exception) {
throw exception;
}
}
/**
* Make a directory, including any necessary but nonexistent parent
* directories. If there already exists a file with specified name or
* the directory cannot be created then an exception is thrown.
*
* @param directory directory to create, must not be <code>null</code>
* @throws NullPointerException if the directory is <code>null</code>
* @throws IOException if the directory cannot be created
*/
public static void forceMkdir(File directory) throws IOException {
if (directory.exists()) {
if (directory.isFile()) {
String message =
"File "
+ directory
+ " exists and is "
+ "not a directory. Unable to create directory.";
throw new IOException(message);
}
} else {
if (!directory.mkdirs()) {
String message =
"Unable to create directory " + directory;
throw new IOException(message);
}
}
}
//-----------------------------------------------------------------------
/**
* Recursively count size of a directory (sum of the length of all files).
*
* @param directory directory to inspect, must not be <code>null</code>
* @return size of directory in bytes, 0 if directory is security restricted
* @throws NullPointerException if the directory is <code>null</code>
*/
public static long sizeOfDirectory(File directory) {
if (!directory.exists()) {
String message = directory + " does not exist";
throw new IllegalArgumentException(message);
}
if (!directory.isDirectory()) {
String message = directory + " is not a directory";
throw new IllegalArgumentException(message);
}
long size = 0;
File[] files = directory.listFiles();
if (files == null) { // null if security restricted
return 0L;
}
for (int i = 0; i < files.length; i++) {
File file = files[i];
if (file.isDirectory()) {
size += sizeOfDirectory(file);
} else {
size += file.length();
}
}
return size;
}
//-----------------------------------------------------------------------
/**
* Tests if the specified <code>File</code> is newer than the reference
* <code>File</code>.
*
* @param file the <code>File</code> of which the modification date must
* be compared, must not be <code>null</code>
* @param reference the <code>File</code> of which the modification date
* is used, must not be <code>null</code>
* @return true if the <code>File</code> exists and has been modified more
* recently than the reference <code>File</code>
* @throws IllegalArgumentException if the file is <code>null</code>
* @throws IllegalArgumentException if the reference file is <code>null</code> or doesn't exist
*/
public static boolean isFileNewer(File file, File reference) {
if (reference == null) {
throw new IllegalArgumentException("No specified reference file");
}
if (!reference.exists()) {
throw new IllegalArgumentException("The reference file '"
+ file + "' doesn't exist");
}
return isFileNewer(file, reference.lastModified());
}
/**
* Tests if the specified <code>File</code> is newer than the specified
* <code>Date</code>.
*
* @param file the <code>File</code> of which the modification date
* must be compared, must not be <code>null</code>
* @param date the date reference, must not be <code>null</code>
* @return true if the <code>File</code> exists and has been modified
* after the given <code>Date</code>.
* @throws IllegalArgumentException if the file is <code>null</code>
* @throws IllegalArgumentException if the date is <code>null</code>
*/
public static boolean isFileNewer(File file, Date date) {
if (date == null) {
throw new IllegalArgumentException("No specified date");
}
return isFileNewer(file, date.getTime());
}
/**
* Tests if the specified <code>File</code> is newer than the specified
* time reference.
*
* @param file the <code>File</code> of which the modification date must
* be compared, must not be <code>null</code>
* @param timeMillis the time reference measured in milliseconds since the
* epoch (00:00:00 GMT, January 1, 1970)
* @return true if the <code>File</code> exists and has been modified after
* the given time reference.
* @throws IllegalArgumentException if the file is <code>null</code>
*/
public static boolean isFileNewer(File file, long timeMillis) {
if (file == null) {
throw new IllegalArgumentException("No specified file");
}
if (!file.exists()) {
return false;
}
return file.lastModified() > timeMillis;
}
//-----------------------------------------------------------------------
/**
* Tests if the specified <code>File</code> is older than the reference
* <code>File</code>.
*
* @param file the <code>File</code> of which the modification date must
* be compared, must not be <code>null</code>
* @param reference the <code>File</code> of which the modification date
* is used, must not be <code>null</code>
* @return true if the <code>File</code> exists and has been modified before
* the reference <code>File</code>
* @throws IllegalArgumentException if the file is <code>null</code>
* @throws IllegalArgumentException if the reference file is <code>null</code> or doesn't exist
*/
public static boolean isFileOlder(File file, File reference) {
if (reference == null) {
throw new IllegalArgumentException("No specified reference file");
}
if (!reference.exists()) {
throw new IllegalArgumentException("The reference file '"
+ file + "' doesn't exist");
}
return isFileOlder(file, reference.lastModified());
}
/**
* Tests if the specified <code>File</code> is older than the specified
* <code>Date</code>.
*
* @param file the <code>File</code> of which the modification date
* must be compared, must not be <code>null</code>
* @param date the date reference, must not be <code>null</code>
* @return true if the <code>File</code> exists and has been modified
* before the given <code>Date</code>.
* @throws IllegalArgumentException if the file is <code>null</code>
* @throws IllegalArgumentException if the date is <code>null</code>
*/
public static boolean isFileOlder(File file, Date date) {
if (date == null) {
throw new IllegalArgumentException("No specified date");
}
return isFileOlder(file, date.getTime());
}
/**
* Tests if the specified <code>File</code> is older than the specified
* time reference.
*
* @param file the <code>File</code> of which the modification date must
* be compared, must not be <code>null</code>
* @param timeMillis the time reference measured in milliseconds since the
* epoch (00:00:00 GMT, January 1, 1970)
* @return true if the <code>File</code> exists and has been modified before
* the given time reference.
* @throws IllegalArgumentException if the file is <code>null</code>
*/
public static boolean isFileOlder(File file, long timeMillis) {
if (file == null) {
throw new IllegalArgumentException("No specified file");
}
if (!file.exists()) {
return false;
}
return file.lastModified() < timeMillis;
}
//-----------------------------------------------------------------------
/**
* Computes the checksum of a file using the CRC32 checksum routine.
* The value of the checksum is returned.
*
* @param file the file to checksum, must not be <code>null</code>
* @return the checksum value
* @throws NullPointerException if the file or checksum is <code>null</code>
* @throws IllegalArgumentException if the file is a directory
* @throws IOException if an IO error occurs reading the file
* @since Commons IO 1.3
*/
public static long checksumCRC32(File file) throws IOException {
CRC32 crc = new CRC32();
checksum(file, crc);
return crc.getValue();
}
/**
* Computes the checksum of a file using the specified checksum object.
* Multiple files may be checked using one <code>Checksum</code> instance
* if desired simply by reusing the same checksum object.
* For example:
* <pre>
* long csum = FileUtils.checksum(file, new CRC32()).getValue();
* </pre>
*
* @param file the file to checksum, must not be <code>null</code>
* @param checksum the checksum object to be used, must not be <code>null</code>
* @return the checksum specified, updated with the content of the file
* @throws NullPointerException if the file or checksum is <code>null</code>
* @throws IllegalArgumentException if the file is a directory
* @throws IOException if an IO error occurs reading the file
* @since Commons IO 1.3
*/
public static Checksum checksum(File file, Checksum checksum) throws IOException {
if (file.isDirectory()) {
throw new IllegalArgumentException("Checksums can't be computed on directories");
}
InputStream in = null;
try {
in = new CheckedInputStream(new FileInputStream(file), checksum);
IOUtils.copy(in, new NullOutputStream());
} finally {
IOUtils.closeQuietly(in);
}
return checksum;
}
}
时间： 2024-10-13 00:15:20