package cn.itcast.字符缓冲流复制文件;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class StringCopy {
        public static void main(String[] args) throws IOException {
                BufferedReader read = new BufferedReader(new FileReader("D:\\2.txt"));
                BufferedWriter write = new BufferedWriter(new FileWriter("F:\\2.txt"));
               
                String line = null;
                while((line=read.readLine())!=null){//一次读取一行
                        write.write(line);
                        write.newLine();
                        write.flush();
                }
                System.out.println("程序运行完毕！");
        }
}

忘记释放资源了  后面需要加上

read.close(); 和 write.close();