Java文件读取

package a.ab;

import java.io.*;

public class FileWrite {
    public static void main(String[] args) {
        FileReader fr=null;
        try{
            File f=new File("D:\\DD\\d.txt");
            int num=0;
            fr=new FileReader(f);
            char [] buf =null;
            
            for(int i=0;i<f.length();i++){
                 buf =new char[3];
                 num=fr.read(buf);
                 if(num==-1){
                     System.out.println("文件已经读取完毕！");
                     break;
                 }
                System.out.println("读取了"+num+"个字符，分别是："+ new String(buf,0,num));
            }
            
            fr.close();
        }catch(Exception ex){
            ex.printStackTrace();
        }
    }
}