Socket里面参数必须为IP地址+端口号java.net.UnknownHostException

报错显示：

C:\Users\wenjrg\Desktop\2019.5.14>java ClickTest
Exception in thread "main" java.net.UnknownHostException: a
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
at java.net.InetAddress.getAllByName0(InetAddress.java:1276)
at java.net.InetAddress.getAllByName(InetAddress.java:1192)
at java.net.InetAddress.getAllByName(InetAddress.java:1126)
at java.net.InetAddress.getByName(InetAddress.java:1076)
at ClickTest.main(ClickTest.java:11)

用Socket实现简单账号密码登录

1. 实现客户端

　　

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.*;

public class ClickTest {
    //模拟用户登录
    public static void main(String[] args) throws IOException {
        //创建socket对象
        Socket s=new Socket(InetAddress.getByName("127.0.0.1"),8888);
        //Socket s=new Socket("itheima",8888);
        //获取用户名和密码
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        System.out.println("请输入用户名：");
        String username=br.readLine();
        System.out.println("请输入密码：");
        String password=br.readLine();
        //获取输出流对象(换行)
        PrintWriter out=new PrintWriter(s.getOutputStream(),true);
        //写出数据
        out.println(username);
        out.println(password);
        //获取输入流对象
        BufferedReader serverBr=new BufferedReader(new InputStreamReader(s.getInputStream()));
        //获取服务器返回的数据
        String result=serverBr.readLine();
        System.out.println(result);
        //释放
        s.close();

    }

}

 

2.服务端

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class ServerTest {

    public static void main(String[] args) throws IOException {
        //创建服务器端socket对象
        ServerSocket ss=new ServerSocket(8888);
        //监听
        Socket s=ss.accept();
        //获取输入流对象
        BufferedReader br=new BufferedReader(new InputStreamReader(s.getInputStream()));
        //判断用户名和密码是否正确
        String username=br.readLine();
        String password=br.readLine();
        //返回判断信息
        boolean flag=false;
        if("a".equals(username)&&"1234".equals(password)){
                flag=true;
         }
        PrintWriter out=new PrintWriter(s.getOutputStream(),true);
                
        if(flag){
            out.println("登陆成功");
        }else{
            out.println("登录失败");
        }
        //释放资源
        s.close();
        //ss.close() 服务器不关闭

    }

}