Socket实现上传下载

import java.io.BufferedInputStream;
        import java.io.BufferedOutputStream;
        import java.io.DataOutputStream;
        import java.io.FileOutputStream;
        import java.io.IOException;
        import java.io.InputStream;
        import java.net.ServerSocket;
        import java.net.Socket;
//服务端server
public class  upload{
    public static void main(String[] args) throws Exception {
        System.out.println("================服务端server==============");
        ServerSocket ss = new ServerSocket(8888);
        Socket socket = ss.accept();
        //读取客户端发送的数据
        BufferedInputStream buf = new BufferedInputStream(socket.getInputStream());
        //将客户端发送的数据读取到本地
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("E:\\q1.txt"));
        byte[] b = new byte[1024];
        int len = 0;
        //边读边写
        while ((len = buf.read(b)) != -1) {
            bos.write(b,0,len);
            bos.flush();
        }
        System.out.println("写出完毕");
        //发送消息到客户端
        DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
        dos.writeUTF("上传成功");
        dos.flush();
        dos.close();
        bos.close();
        buf.close();
    }
}

import java.io.*;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;

//客户端
public class download {
    public static void main(String[] args) throws Exception, IOException {
        System.out.println("================客户端Client==============");
        Socket socket = new Socket("127.0.0.1", 8888);
        //获取读取文件的输入流
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream("E:\\q.txt"));
        //输出信息到服务端的输出流
        BufferedOutputStream bos = new BufferedOutputStream(socket.getOutputStream());
        byte [] b = new byte[1024];
        int len = 0;
        //边读边写
        while((len=bis.read(b))!=-1){
            bos.write(b, 0, len);
            bos.flush();
        }
        //在不关闭socket的条件下关闭输出流
        socket.shutdownOutput();
        //获取服务端反馈消息的输入流
        DataInputStream dis = new DataInputStream(socket.getInputStream());
        String mess = dis.readUTF();
        System.out.println(mess);

    }
}