java缓存读写文件小例子

package com.taoniwu;
import java.util.regex.*;
import java.io.*;

publicclass TestRead {
publicstaticvoid main (String[] args) {
        File file=new File ("D://web.txt");

try
        {
            BufferedReader input=new BufferedReader (new FileReader (file) );
            String text;
int sum = 0;
            File txt = new File("d://web.html");
//判断文件是否存在
if(!txt.exists()){
                txt.createNewFile();
            }
else{
                txt.delete();
            }
            FileWriter fw=new FileWriter( "d://web.html",true);
            BufferedWriter bw=new BufferedWriter(fw);
            String sr = "";
while ( (text=input.readLine() ) !=null) {
//正则表达，过滤非www开头的网址
                Pattern p = Pattern.compile ("http://www.*./");
                Matcher m = p.matcher (text);
while (m.find()) //查找符合pattern的字符串
                {
//过滤带”baidu“和带”tarena”的url，并叠加链接代码
if(m.group().indexOf("baidu") == -1 && m.group().indexOf("tarena") == -1 && m.group().indexOf("aowin") == -1)
                    {
                        sr = sr + sum + "、<a target="_blank" href=""+m.group()+"">"+m.group()+"</a><br />n";
                        sum++;
                    }
//添加缓存，当缓存达到30k时写入，并把sr清空
if(sr.length()>30720){
                        bw.write(sr);
                        sr = "";
                    }
                }
            }
            bw.write(sr+"n");
            bw.close();

        } catch (Exception ex) {
            System.out.println (ex+"错误");
        }
        System.out.println("完成！");
    }
}

代码来自： http://www.taoniwu.com/archives/2984.html