java缓存读写文件小例子

在一个叫掏你屋的博客上看到的小例子，缓存读写文件：

 

1. package com.taoniwu; 
2. import java.util.regex.*; 
3. import java.io.*; 
4.  
5. public class TestRead { 
6.     public static void main (String[] args) { 
7.         File file=new File ("D://web.txt"); 
8.  
9.         try 
10.         { 
11.             BufferedReader input=new BufferedReader (new FileReader (file) ); 
12.             String text; 
13.             int sum = 0; 
14.             File txt = new File("d://web.html"); 
15.             //判断文件是否存在 
16.             if(!txt.exists()){ 
17.                 txt.createNewFile(); 
18.             } 
19.             else{ 
20.                 txt.delete(); 
21.             } 
22.             FileWriter fw=new FileWriter( "d://web.html",true); 
23.             BufferedWriter bw=new BufferedWriter(fw); 
24.             String sr = ""; 
25.             while ( (text=input.readLine() ) !=null) { 
26.                 //正则表达，过滤非www开头的网址 
27.                 Pattern p = Pattern.compile ("http://www.*./"); 
28.                 Matcher m = p.matcher (text); 
29.                 while (m.find()) //查找符合pattern的字符串 
30.                 { 
31.                     //过滤带”baidu“和带”tarena”的url，并叠加链接代码 
32.                     if(m.group().indexOf("baidu") == -1 && m.group().indexOf("tarena") == -1 && m.group().indexOf("aowin") == -1) 
33.                     { 
34.                         sr = sr + sum + "、" href=""+m.group()+"">"+m.group()+"
    n"; 
35.                         sum++; 
36.                     } 
37.                     //添加缓存，当缓存达到30k时写入，并把sr清空 
38.                     if(sr.length()>30720){ 
39.                         bw.write(sr); 
40.                         sr = ""; 
41.                     } 
42.                 } 
43.             } 
44.             bw.write(sr+"n"); 
45.             bw.close(); 
46.  
47.         } catch (Exception ex) { 
48.             System.out.println (ex+"错误"); 
49.         } 
50.         System.out.println("完成！"); 
51.     } 
52. }