一、文件操作
1、File类:对文件的外部操作
2、RandomAccessFile类:对文件的内容操作
代码演练1：
要求:1、创建目录A，A下有目录B和C，B中有目录D和文件b.txt,D中有文件d.txt，C中有文件c.jpg
2、遍历A中所有文件和目录
3、遍历A中jpg格式的文件
4、删除A中所有内容包括A
package BlogCode;
import java.io.*;
public class 代码演练1 {
private static Object file;
public static void main(String[] args) {
/**
* "."表示当前目录
* ".."表示上一目录
* File.separator 表示分隔符
*
*/
File dir = new File("."+File.separator+"A");
if(!dir.exists()){
dir.mkdir();
}
File dir1 = new File("."+File.separator+"A"+"."+File.separator+"B"+"."+File.separator+"D");
if(!dir1.exists()){
dir1.mkdirs();
}
File dir2 = new File("."+File.separator+"A"+"."+File.separator+"C");
if(!dir2.exists()){
dir2.mkdirs();
}
File b = new File("."+File.separator+"A"+"."+File.separator+"B"+"."+File.separator+"b.txt");
if(!b.exists()){
try {
b.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
File c = new File("."+File.separator+"A"+"."+File.separator+"C"+"."+File.separator+"c.jpg");
if(!c.exists()){
try {
c.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
File d = new File("."+File.separator+"A"+"."+File.separator+"B"+"."+File.separator+"D"+"."+File.separator+"d.txt");
if(!d.exists()){
try {
d.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
findAllFile(dir);
findjpg(dir);
deleteAll(dir);
}
private static void findjpg(File dir) {
// FileFilter ff = new FileFilter() {
// public boolean accept(File pathname) {
// return pathname.getName().endsWith(".jpg");
// }
// };
File[] subs = dir.listFiles();
for(File sub:subs){
if(sub.isFile()&&sub.getName().endsWith(".jpg")){
System.out.println("文件.jpg:"+sub.getName());
}else if(sub.isDirectory()){
findjpg(sub);
}
}
}
private static void findAllFile(File dir) {
File[] subs = dir.listFiles();
for(File sub:subs){
if(sub.isFile()){
System.out.println("文件:"+sub.getName());
}else{
findAllFile(sub);
System.out.println("目录:"+sub.getName());
}
}
}
private static void deleteAll(File dir) {
File[] subs = dir.listFiles();
for(File sub:subs){
if(sub.isFile()){
sub.delete();
}else{
deleteAll(sub);
sub.delete();
}
}
dir.delete();
}
}
代码演练2：
要求:1、创建一个demo.txt文件并输入“你好，java!”,将全部内容复制到demo1_copy.txt中，输出“av”并将其复制到demo2_copy.txt中
package BlogCode;
import java.io.*;
public class 代码演练2 {
public static void main(String[] args) throws IOException {
/**
* RandomAccessFile 用指针操作
*/
RandomAccessFile raf = new RandomAccessFile("demo.txt", "rw");
RandomAccessFile raf1 = new RandomAccessFile("demo1_copy1.txt", "rw");
RandomAccessFile raf2 = new RandomAccessFile("demo1_copy2.txt", "rw");
raf.write("你好，java!".getBytes());
long getPointerindex = raf.getFilePointer();
System.out.println(getPointerindex);
raf.seek(0);
int r =-1;
while((r=raf.read())!=-1){
raf1.write(r);
}
raf.seek(0);
byte[] by = new byte[20];
while(raf.read(by)!=-1){
raf2.write(by);
System.out.println(new String(by,7,2,"GBK"));
}
raf1.close();
raf2.close();
}
}
二、IO流
2.1.字节流:InputStream 是所有字节输入流的父类
OutputStream 是所有字节输出流的父类
2.1.1.文件流(低级流):FileInputStream 文件输入流-----------FIS
FileOutputStream 文件输出流-----------FOS
2.1.2.缓冲流:BufferedInputStream 缓冲输入流---------BIS
BufferedOutputStream 缓冲输出流---------BOS
2.1.3.对象流:ObjectInputStream 对象输入流-----------OIS
ObjectOutputStream 对象输出流-----------OOS
2.2.字符流:Reader 是所有字符输入流的父类
Writer 是所有字符输出流的父类
2.2.1.转换流:InputStreamReader 字符输入流----------ISR
OutputStreamWriter 字符输出流---------OSW
2.2.2缓冲字符流:BufferedReader 缓冲字符输入流--------BR
PrintWriter 缓冲字符输出流----------PW
代码演练3:
要求:1.用字节流将"旋转的卡特琳娜"写入文件lol.txt中，并将"卡特"输出
2.用缓冲流将"旋转的德玛西亚之力"写入文件lol1.txt中，并将文件内容复制到lol2.txt
package BlogCode;
import java.io.*;
public class 代码演练3 {
public static void main(String[] args) throws Exception {
FileOutputStream fos = new FileOutputStream("lol.txt");
fos.write("旋转的卡特琳娜".getBytes());
FileInputStream fis = new FileInputStream("lol.txt");
byte[] by1 = new byte[15];
fis.read(by1);
System.out.println(new String(by1,6,4));
fos.close();
fis.close();
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("lol1.txt"));
bos.write("旋转的德玛西亚之力".getBytes());
bos.flush();
BufferedInputStream bis = new BufferedInputStream(new FileInputStream("lol1.txt"));
BufferedOutputStream bos1 = new BufferedOutputStream(new FileOutputStream("lol2.txt"));
int r=-1;
while((r=bis.read())!=-1){
bos1.write(r);
}
bos1.close();
bos.close();
bis.close();
}
}
代码演练4:
要求:1.建立一个Person类，在测试类中创建一个Person对象，并将其序列化和反序列化
2.在测试类中创建一个Person对象数组，并将其序列化和反序列化
package BlogCode;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
public class 代码演练4 {
/**
* 注意要序列化的类必须实现Serializable接口，并要定义序列版本号serialVersionUID
*/
public static void main(String[] args) throws Exception {
Person p = new Person("miss",26);
ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("pp.obj"));
oos.writeObject(p);
oos.close();
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("pp.obj"));
Person p0 = (Person) ois.readObject();
System.out.println(p0);
ois.close();
System.out.println("--------------------");
Person p1 = new Person("熊大",12);
Person p2 = new Person("熊二",13);
Person p3 = new Person("光头强",30);
Set<Person> s = new HashSet<Person>();
s.add(p1);
s.add(p2);
s.add(p3);
ObjectOutputStream oos1 = new ObjectOutputStream(new FileOutputStream("pp1.obj"));
oos1.writeObject(s);
oos1.close();
ObjectInputStream ois1 = new ObjectInputStream(new FileInputStream("pp1.obj"));
Set<Person> set = (Set)ois1.readObject();
for(Person o:set){
System.out.println(o);
}
ois1.close();
}
}
class Person implements Serializable{
private static final long serialVersionUID = 1L;
private String name;
private int age;
public Person() {
super();
}
public Person(String name, int age) {
super();
this.name = name;
this.age = age;
}
public String toString() {
return "Person [name=" + name + ", age=" + age + "]";
}
}
代码演练5:
要求:用字符流将"我只有飞速的旋转，才能止住我的泪水，忘记你的模样"输入文件demo5.txt，并将内容输出
package BlogCode;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
public class 代码演练5 {
public static void main(String[] args) throws Exception, FileNotFoundException {
OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("demo5.txt"), "GBK");
osw.write("我只有飞速的旋转，才能止住我的泪水，忘记你的模样");
osw.close();
InputStreamReader isr = new InputStreamReader(new FileInputStream("demo5.txt"),"GBK");
int r =-1;
while((r=isr.read())!=-1){
System.out.print((char)r);
}
isr.close();
}
}
代码演练6:
要求:用缓冲字符流将"平生不修善果，最爱杀人放火。
忽地顿开金绳，这里扯断玉锁。
咦，钱塘江上潮信来，今日方知我是我!
--------------花和尚:鲁智深"
package BlogCode;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
public class 代码演练6 {
public static void main(String[] args) throws Exception {
FileOutputStream fos = new FileOutputStream("demo06.txt");
OutputStreamWriter osw = new OutputStreamWriter(fos, "GBK");
PrintWriter pw = new PrintWriter(osw,true);
pw.println("平生不修善果，最爱杀人放火。");
pw.println("忽地顿开金绳，这里扯断玉锁。");
pw.println("咦，钱塘江上潮信来，今日方知我是我!");
pw.println(" ------------------花和尚:鲁智深");
pw.flush();
pw.close();
FileInputStream fis = new FileInputStream("demo06.txt");
InputStreamReader isr = new InputStreamReader(fis,"GBK");
BufferedReader br = new BufferedReader(isr);
String s = null;
while((s=br.readLine())!=null){
System.out.println(s);
}
}
}
时间： 2024-10-12 08:00:21