zoukankan html css js c++ java

java_IO流小结

字符流和字节流的主要区别：

1.字节流读取的时候，读到一个字节就返回一个字节；字符流使用了字节流读到一个或多个字节（中文对应的字节数是两个，在UTF-8码表中是3个字节）时。先去查指定的编码表，将查到的字符返回。

2.字节流可以处理所有类型数据，如：图片，MP3，AVI视频文件，而字符流只能处理字符数据。只要是处理纯文本数据，就要优先考虑使用字符流，除此之外都用字节流。

字节流：

1、通过字节流写数据

code：

 1 package com.test;
 2 
 3 import java.io.FileNotFoundException;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 import java.io.UnsupportedEncodingException;
 7 
 8 
 9 public class WriteByteStream {
10 
11     public static void main(String[] args) {
12         try {
13             
14             
15             FileOutputStream fos = new FileOutputStream("textw.txt");
16             String outString = "write 123456写出数据";
17             byte output[] = outString.getBytes("UTF-8");
18             fos.write(output);
19             fos.close();
20             
21             
22         } catch (FileNotFoundException e) {
23             e.printStackTrace();
24         } catch (UnsupportedEncodingException e) {
25             e.printStackTrace();
26         } catch (IOException e) {
27             e.printStackTrace();
28         }
29     }
30 
31 }

2、通过字节流读数据：

code：

 1 package com.test;
 2 
 3 import java.io.FileInputStream;
 4 import java.io.FileNotFoundException;
 5 import java.io.IOException;
 6 import java.io.UnsupportedEncodingException;
 7 
 8 
 9 
10 public class ReadByteStream {
11 
12     public static void main(String[] args) {
13         try {
14             FileInputStream fis = new FileInputStream("text.txt");
15             byte input[] = new  byte[21];
16             fis.read(input);
17             
18             String inputString = new String(input, "UTF-8");
19             System.out.println(inputString);
20             fis.close();
21             
22         } catch (FileNotFoundException e) {
23             e.printStackTrace();
24         } catch (UnsupportedEncodingException e) {
25             e.printStackTrace();
26         } catch (IOException e) {
27             e.printStackTrace();
28         }
29 
30     }
31 
32 }

3、使用字节流读写数据

code：

 1 package com.test;
 2 
 3 import java.io.FileInputStream;
 4 import java.io.FileNotFoundException;
 5 import java.io.FileOutputStream;
 6 import java.io.IOException;  
 7  
 8 
 9 public class CopyByByteStream {
10 
11     public static void main(String[] args) {
12         try {
13             
14             
15             
16             FileInputStream fis = new FileInputStream("movie.mp4");
17             FileOutputStream fos = new FileOutputStream("movie_new.mp4");
18             
19             byte input[] = new byte[50];
20             long before = System.currentTimeMillis();
21             int count = 0;
22             while (fis.read(input) != -1) {
23                 fos.write(input);
24                 count++;
25             }
26             fos.flush();
27             fis.close();
28             fos.close();
29             System.out.println(System.currentTimeMillis()-before+"ms");
30             System.out.println("done");
31             
32             
33             
34         } catch (FileNotFoundException e) {
35             e.printStackTrace();
36         } catch (IOException e) {
37             e.printStackTrace();
38         }
39     }
40 
41 }

4、使用带缓冲的字节流读写数据（字节流模板）

code：

 1 package com.test;
 2 import java.io.BufferedInputStream;
 3 import java.io.BufferedOutputStream;
 4 import java.io.FileInputStream;
 5 import java.io.FileNotFoundException;
 6 import java.io.FileOutputStream;
 7 import java.io.IOException;
 8 
 9 
10 
11 public class ReadByBufferedByteStream {
12 
13     public static void main(String[] args) {
14         try {
15             
16             
17             FileInputStream fis = new FileInputStream("movie.mp4");
18             BufferedInputStream bis = new BufferedInputStream(fis,1000000);
19             FileOutputStream fos = new FileOutputStream("moive_new.mp4");
20             BufferedOutputStream bos = new BufferedOutputStream(fos,1000000);
21             //大型文件对应的数组可以大一些，小文件对应的数组小一些
22             byte input[] = new byte[100000];
23             int count = 0;
24             long before = System.currentTimeMillis();
25             while (bis.read(input) != -1) {
26                 bos.write(input);
27                 count++;
28             }
29             bos.flush();
30             bis.close();
31             fis.close();
32             bos.close();
33             fos.close();
34             System.out.println(System.currentTimeMillis()-before+"ms");
35             System.out.println("读取了："+count+"次");
36             
37             
38             
39         } catch (FileNotFoundException e) {
40             e.printStackTrace();
41         } catch (IOException e) {
42             e.printStackTrace();
43         }
44     }
45 
46 }

字符流：

1、使用字符流读写数据

code：

 1 import java.io.File;
 2 import java.io.FileInputStream;
 3 import java.io.FileNotFoundException;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 import java.io.InputStreamReader;
 7 import java.io.OutputStreamWriter;
 8 import java.io.UnsupportedEncodingException;
 9 
10 
11 public class RWByCharStream {
12 
13     public static void main(String[] args) {
14         try {
15             
16             
17             //File file = new File("java.txt");
18             FileInputStream fis = new FileInputStream("java.txt");
19             FileOutputStream fos = new FileOutputStream("java_new.txt");
20             InputStreamReader isr = new InputStreamReader(fis, "UTF-8");
21             OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
22             char input[] = new char[100];
23             int l = 0;
24             while ((l = isr.read(input)) != -1) {
25                 //String inputString = new String(input,0,l);
26                 osw.write(input,0,l);
27             }
28             isr.close();
29             fis.close();
30             osw.close();
31             fos.close();
32             System.out.println("done");
33             
34         } catch (FileNotFoundException e) {
35             e.printStackTrace();
36         } catch (UnsupportedEncodingException e) {
37             e.printStackTrace();
38         } catch (IOException e) {
39             e.printStackTrace();
40         }
41         
42     }
43 
44 }

2、使用带有缓冲的字符流读写数据（字符流模板）

code：

 1 import java.io.BufferedReader;
 2 import java.io.BufferedWriter;
 3 import java.io.FileInputStream;
 4 import java.io.FileNotFoundException;
 5 import java.io.FileOutputStream;
 6 import java.io.IOException;
 7 import java.io.InputStreamReader;
 8 import java.io.OutputStreamWriter;
 9 import java.io.PrintWriter;
10 import java.io.UnsupportedEncodingException;
11 
12 
13 public class RWByBufferedCharStream {
14 
15     public static void main(String[] args) {
16         try {
17 
18 
19             //File file = new File("java.txt");
20             FileInputStream fis = new FileInputStream("java.txt");
21             FileOutputStream fos = new FileOutputStream("java_new_buff.txt");
22             InputStreamReader isr = new InputStreamReader(fis, "UTF-8");
23             OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
24             
25             BufferedReader br = new BufferedReader(isr);
26             //BufferedWriter bw = new BufferedWriter(osw);
27             PrintWriter pw = new PrintWriter(osw,true);
28             
29             String input;
30             while ((input = br.readLine()) != null) {
31                 //bw.write(input);
32                 pw.println(input);
33             }
34             br.close();
35             //bw.flush();bw.close();
36             pw.close();
37             isr.close();
38             fis.close();
39             osw.close();
40             fos.close();
41             System.out.println("done");
42 
43         } catch (FileNotFoundException e) {
44             e.printStackTrace();
45         } catch (UnsupportedEncodingException e) {
46             e.printStackTrace();
47         } catch (IOException e) {
48             e.printStackTrace();
49         }
50     }
51 
52 }

查看全文

相关阅读:
顶点与片段着色器的例子
 Unity cg vertex and fragment shaders(二)
Unity cg vertex and fragment shaders(一)
C#线程(一)
shell脚本变量定义注意别跟系统变量重名了……
VLC编译问题
 VIM技巧：翻页
 Linux命令：cd
Linux设置：环境变量
 VIM技巧：显示行号

原文地址：https://www.cnblogs.com/UniqueColor/p/5708818.html