文件压缩

/*
对文件的简单压缩
读取每一行数据，连续相同的字符变成 个数+字符
例如：aaaa->4a  d->d
*/
import java.io.*;
class test_one 
{
public static void main(String[] args) throws Exception
{
BufferedReader bufr = new BufferedReader(new FileReader("a.txt"));
BufferedWriter bufw = new BufferedWriter(new FileWriter("b.txt"));
String line = null;
while((line=bufr.readLine())!=null){
String str = yasuo(line);
bufw.write(str);
bufw.newLine();
bufw.flush();
}
}
public static String yasuo(String str){
StringBuilder sb = new StringBuilder();
        char[] ch = str.toCharArray();
        int n = str.length();
        int count = 1;
        int maxlength = 0;
        for(int i=0;i<n-1;i++){
        if(ch[i]==ch[i+1]){
        count++;
        if(i==n-2){
if(count==1)
        sb.append(ch[i]);
else
sb.append(count+""+ch[i]);
        }
        }else{
         if(count==1)
        sb.append(ch[i]);
else
sb.append(count+""+ch[i]);
        count=1;
        if(i==n-2){
        if(count==1)
        sb.append(ch[i+1]);
else
sb.append(count+""+ch[i+1]);
        }
        }
        }
        return sb.toString();
}
}