黑马程序员——IO流总结

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什么是IO流?

IO流是用来处理设备之间的数据传输

有哪些流？

流按操作数据的种类分为：字符流和字节流

流按流的方向分：输入流和输出流

字节流的基类：InputStream和OutputStream

字符流的基类：Writer和Reader

常用写字符流：FileWriter,BufferedWriter,OutputStreamWriter,PrinterWriter

常用读字符流  : FileReader,BufferedReader,OutputStreamReader

常用输入字节流：FileInputStream.BufferedInputStream

常用输出字节流：FileOutputStream,BufferedOutputStream,PrinterStream

装饰设计模式：把已有对象传入到一个新的类中，实现其功能的增强

File类常见操作：

1：创建

File file = new File("D:\\ee\\cc.txt");

file.createNewFile();

file.mkdir();

2：删除

file.delete();

file.deleteOnExit();

3：判断

file.exist();

file.isDirectory();

file.isFile();

file.isAbsloute()

file.isHidden()

4：获取

file.getPath();

file.getName();

file.getParent();

file.getAbsolutePath();

file.lastModified();

file.length();

file.listRoots();

file.list();

file.listFiles();

 1 练习
 2 package blogtest1;
 3
 4 import java.io.FileWriter;
 5
 6 /*
 7  * 对文件的续写
 8  */
 9
10 public class IOTest1 {
11
12  public static void main(String[] args)throws Exception {
13   FileWriter file = new FileWriter("C:\\Users\\Administrator\\Desktop\\ee.txt",true);
14   file.write("welcome to China");
15   file.close();
16
17  }
18
19 }

 1 练习
 2 package blogtest1;
 3
 4 import java.io.File;
 5
 6 public class IOTest2 {
 7
 8  /**
 9   * 读取一个目录中所以.java文件，并打印到控制台
10   */
11  public static void main(String[] args) {
12
13   File file = new File("F:\\yueming");
14   String[] str = file.list();
15   StringBuilder stringbuilder = new StringBuilder();
16   for(int i = 0 ; i < str.length; i++){
17    if(str[i].endsWith(".java")){
18     stringbuilder.append(str[i]+"\r\n");
19    }
20   }
21   System.out.println(stringbuilder);
22  }
23
24 }

 1 练习
 2 package blogtest1;
 3 import java.io.*;
 4
 5 public class IOTest3 {
 6
 7  /**
 8   * 将C盘的文件复制到D盘
 9   */
10  public static void main(String[] args) throws Exception{
11   FileReader filereader = new FileReader("C:\\ee.txt");
12   FileWriter  filewriter = new FileWriter("D:\\aa.txt");
13   char[]  a = new char[1024];
14   int len = 0;
15   while((len = filereader.read(a))!= -1){
16    filewriter.write(a,0,len);
17   }
18   filereader.close();
19   filewriter.close();
20
21  }
22
23 }

 1 练习
 2 package blogtest1;
 3 import java.io.*;
 4
 5 public class IOTest4 {
 6
 7  /**
 8   * 将C盘的图片复制到D盘中
 9   */
10  public static void main(String[] args) throws Exception{
11   BufferedInputStream buff1 = new BufferedInputStream(new FileInputStream("C:\\dd.jpg"));
12   BufferedOutputStream buff2 = new BufferedOutputStream(new FileOutputStream("D:\\tt.jpg"));
13   byte[] a = new byte[1024];
14   int len = 0;
15   while((len = buff1.read(a))!= -1){
16    buff2.write(a,0,len);
17   }
18
19
20  }
21
22 }

 1 练习
 2 package blogtest1;
 3 import java.util.*;
 4 import java.io.*;
 5
 6 public class IOTest5 {
 7
 8  /**
 9   * 演示Properties流功能
10   */
11  public static void main (String[] args) throws Exception{
12   Properties properties = new Properties();
13   properties.setProperty("zhangshan", "22");
14   properties.setProperty("lisi", "33");
15   properties.setProperty("wangwu","25");
16   properties.put("fuli", "45");
17   System.out.println(properties.getProperty("lisi"));
18
19
20   Set set = properties.keySet();
21   Iterator ite = set.iterator();
22   while(ite.hasNext()){
23    String key = (String)ite.next();
24    String value = (String)properties.get(key);
25    System.out.println(key + "....." + value);
26   }
27
28
29
30  }
31
32 }

 1 练习
 2 /*BufferedInputStream自定义实现*/
 3 import java.io.*;
 4 public class BufferedInputStreamTest
 5 {
 6  public static void main(String[] args) throws IOException
 7  {
 8   FileInputStream file1 = new FileInputStream("F:\\BaiduYunDownload\\第01天\\003_Java环境搭建(安装)_黑马程序员_Java基础视频.avi");
 9   FileOutputStream file2 = new FileOutputStream("D:\\yueyue.avi");
10   MyBufferedInputStream buff1 = new MyBufferedInputStream(file1);
11   BufferedOutputStream buff2 = new BufferedOutputStream(file2);
12   int len = 0;
13
14
15   while( (len = buff1.myRead()) != -1)
16   {
17
18    buff2.write(len);
19   }
20
21   buff1.myClose();
22   buff2.close();
23
24
25
26
27  }
28 }
29
30 class MyBufferedInputStream
31 {
32  private InputStream file = null;
33  byte[] a = new byte[1024*4];
34  int pos = 0;
35  int count = 0;
36
37  MyBufferedInputStream(InputStream file)
38  {
39   this.file = file;
40  }
41  public int myRead() throws IOException
42  {
43   if(count ==0)
44   {
45    count = file.read(a);
46    if(count<0)
47     return -1;
48    pos = 0;
49    byte b = a[pos];
50    count--;
51    pos++;
52    return b&255;
53   }
54   else if(count > 0)
55   {
56    byte b = a[pos];
57    count--;
58    pos++;
59    return b&255;
60   }
61   return -2;
62  }
63  public void myClose() throws IOException
64  {
65   file.close();
66  }
67
68
69
70
71
72 }