首先呢看一下需求吧：将A 电脑 d 盘的 文件  下载 到 B 电脑 的E盘 根目录 。因为小编只有一台电脑，所以也只能从简，但是思路都是一样的。不多说，程序献上：

客户端程序：

package com.liubo;

import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.net.Socket;

public class ClientDemo {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        try {
            Socket socket=new Socket("localhost",6667);
            OutputStream  os = socket.getOutputStream();//网卡流
            InputStream  is = socket.getInputStream();

            FileOutputStream fos = new FileOutputStream("h:/books.xml");

            byte [] b = new byte[1024];
            int len = 0;
            while( (len=is.read(b))!= -1 ){
                fos.write(b, 0, len);
            }
            fos.close();
            is.close();

        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

}

服务器端：

package com.liubo;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class ServiceDemo {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        ServerSocket ss=null;
        Socket socket=null;
        try {
            ss=new ServerSocket(6667);
            socket=ss.accept();
            InputStream is=socket.getInputStream();
            OutputStream  os = socket.getOutputStream();
            //读取内容
            byte [] b = new byte[1024];
            int len = 0;
            FileInputStream fis = new FileInputStream("D:/books.xml");
            while( (len=fis.read(b))!= -1 ){
                os.write(b, 0, len);
            }
            os.close();
            fis.close();

        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

}