Java实现文件的读写，复制

 1 import java.io.BufferedInputStream;
 2 import java.io.BufferedOutputStream;
 3 import java.io.FileInputStream;
 4 import java.io.FileOutputStream;
 5 import java.io.InputStream;
 6 import java.io.OutputStream;
 7
 8 /**
 9  * 测试文件的读取、写入、复制功能
10  * @package :java05
11  * @author shaobn
12  * @Describe :测试文件的读取、写入、复制功能
13  * @Time: 2015-9-5 下午10:50:18
14  */
15 public class TestCopyText {
16     public static void main(String[] args) throws Exception{
17         //读取文件并打印
18         System.out.println(readText(new FileInputStream("D:\\hello.txt")));
19         //写入内容至文件
20         writeText(new FileOutputStream("D:\\hellocopy.txt"), "您好，读写文件一般都用字符流，这种方式不推荐！");
21         //复制文件，上面写入文件内容不变
22         writeText(new FileOutputStream("D:\\hellocopy.txt",true),readText(new FileInputStream("D:\\hello.txt")));
23     }
24     //用FileInputStream读取文件
25     public static String readText(InputStream is){
26         BufferedInputStream bis = null;
27         String str = null;
28         try {
29             bis = new BufferedInputStream(is);
30             int len = 0;
31             byte[] by = new byte[1024];
32             while((len=bis.read(by))!=-1){
33                 str = new String(by,0,len);
34             }
35         } catch (Exception e) {
36             // TODO: handle exception
37             e.printStackTrace();
38         }finally{
39             try {
40                 if(bis!=null){
41                     bis.close();
42                     return str;
43                 }
44             } catch (Exception e2) {
45                 // TODO: handle exception
46                 e2.printStackTrace();
47             }
48         }
49         return str;
50     }
51     //用FileOutputStream写入文件
52     public static void writeText(OutputStream os,String str){
53         BufferedOutputStream bos = null;
54         try {
55             bos = new BufferedOutputStream(os);
56             bos.write(str.getBytes());
57         } catch (Exception e) {
58             // TODO: handle exception
59             e.printStackTrace();
60         }finally{
61             try{
62             if(bos!=null){
63                 bos.close();
64             }
65             }catch (Exception e) {
66                 // TODO: handle exception
67                 e.printStackTrace();
68             }
69
70         }
71
72     }
73 }

声明一下：一般读写文本文件均为字符流，笔者用字节流来写，推荐大家使用字符流读写文本文件。