程序代码：

package com.bdqn;

import java.io.*;

public class ChangeTest {
    public static void main(String[] args) {
        FileReader fr = null;
        BufferedWriter bw = null;

        try {
            fr = new FileReader("e:\\hello.txt");
            int result = -1;
            StringBuffer str = new StringBuffer();
            while((result = fr.read())!=-1){
                str.append((char)result);
            }
            System.out.println(str);
            String s = str.toString().replace("{name}","小黄");
            s = s.replace("{type}","哈巴狗");
            s = s.replace("前","后");
            s = s.replace("{master}","大帅");
            System.out.println(s);
            bw = new BufferedWriter(new FileWriter("e:\\hello.txt"));
            bw.write(s);
            bw.flush();
            bw.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                if(fr!=null){
                    fr.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

运行结果