Server.java
package com.zh.socket;

import java.io.IOException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

/*
 * 基于TCP协议的socket通信,实现用户登录
 * 服务器端
 */

public class Server {
    public static void main(String[] args) {
        try {
            //1.创建服务器端socket,即ServerSocket,并绑定指定的端口，并在端口进行监听
            ServerSocket serverSocket=new ServerSocket(8888);
            Socket socket = null;
            //记录客户端的数量
            int count = 0;
            System.out.println("***服务器即将启动,等待客户端的连接***");
            //循环监听等待客户端的连接
            while(true){
                //2.通过accept()方法对客户端进行监听,等待客户端的连接
                socket=serverSocket.accept();//返回的实例用来与客户端进行通信
                ServerThread serverThread = new ServerThread(socket);
                //启动线程
                serverThread.start();
                count++;
                System.out.println("客户端数量: "+count);
                InetAddress address = socket.getInetAddress();
                System.out.println("当前客户端的IP: "+address.getHostAddress());
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

Client.java
package com.zh.socket;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

/*
 * 客户端
 */
public class Client {
    public static void main(String[] args){
        try {
            //1.创建Socket,用于向服务器端发送请求
            Socket socket = new Socket("localhost",8888);
            //2.创建Socket字节输出流
            OutputStream os = socket.getOutputStream();
            //3.将字节输出流包装成Print流
            PrintWriter pw = new PrintWriter(os);
            pw.write("用户名:zh;密码:456");
            pw.flush();
            socket.shutdownOutput();//关闭输出流
            //4.创建输入流接收服务器端响应的数据
            InputStream is = socket.getInputStream();
            BufferedReader br = new BufferedReader(new InputStreamReader(is));
            String info = null;
            while((info=br.readLine())!=null){
                System.out.println("我是客户端,服务器说: "+info);
            }
            socket.shutdownInput();//关闭输入流
            //5.关闭资源
            br.close();
            is.close();
            pw.close();
            os.close();
            socket.close();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

ServerThread.java
package com.zh.socket;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;

/*
 * 服务器线程处理类
 */

public class ServerThread extends Thread {
    //和本线程相关的socket
    Socket socket = null;
    public ServerThread(Socket socket){
        this.socket = socket;
    }
    //线程执行的操作，响应客户端的请求
    public void run(){
        //获取输入流,并读取客户端的信息
        InputStream is = null;
        OutputStream os = null;
        PrintWriter pw = null;
        BufferedReader br = null;
        InputStreamReader isr = null;
        try {
            is = socket.getInputStream();
            isr=new InputStreamReader(is);//将字节流包装为字符流
            br=new BufferedReader(isr);//为输入流添加缓冲
            String info = null;
            while((info=br.readLine())!=null){
                System.out.println("我是服务器,客户端说: "+info);
                }
            socket.shutdownInput();//关闭输入流
                os = socket.getOutputStream();
                pw = new PrintWriter(os);//包装成打印流
                pw.write("欢迎您!");
                pw.flush();
            }catch (IOException e){
            e.printStackTrace();
            }finally{//最终将要执行的一些代码
                try {
                    if(pw!=null)
                        pw.close();
                    if(os!=null)
                        os.close();
                    if(br!=null)
                        br.close();
                    if(isr!=null)
                        isr.close();
                    if(is!=null)
                        is.close();
                    if(socket!=null)
                        socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            } 
    }

}