客户端代码
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;

import javax.imageio.stream.ImageInputStream;

public class Cilent {

 public static void main(String[] args) {
  //1.创建客户端SOcket,指定服务器额端口
  try {
   Socket socket=new Socket("localhost",8888);
   //2/获取输出流，向服务器发送信息
  OutputStream os=socket.getOutputStream();
  PrintWriter pw=new PrintWriter(os);
  pw.write("用户名：admin;密码:123");
  pw.flush();
  socket.shutdownOutput();
  //3.获取输入流
  InputStream ins=socket.getInputStream();
  BufferedReader br=new BufferedReader(new InputStreamReader(ins));
  String info=null ;
  while((info=br.readLine())!=null){
   System.out.println("我是客户端，服务器说："+info);
   info=br.readLine();
  }

  //3.关闭资源
  br.close();
  ins.close();
  pw.close();
  os.close();
  socket.close();
  } catch (UnknownHostException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }

 }

}

客户端的报错

java.net.ConnectException: Connection refused: connect
 at java.net.DualStackPlainSocketImpl.connect0(Native Method)
 at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
 at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
 at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
 at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
 at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
 at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
 at java.net.Socket.connect(Socket.java:589)
 at java.net.Socket.connect(Socket.java:538)
 at java.net.Socket.<init>(Socket.java:434)
 at java.net.Socket.<init>(Socket.java:211)
 at Socket.Cilent.main(Cilent.java:19)

服务端的代码

package 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.ServerSocket;
import java.net.Socket;

/*
 * 给予TCP协议的端
 */
public class Sever {
public static void main(String[] args){
 //1.创建一个服务器
 try {
  ServerSocket scoket1=new ServerSocket(8888);
  //2.调用accept方法
  System.out.println("服务器即将启动，等待客户端的链接***");
  Socket socket=scoket1.accept();
  //3.获取输入流，获取登录信息
  InputStream is=socket.getInputStream();
  InputStreamReader  isr=new InputStreamReader(is);
  BufferedReader br=new BufferedReader(isr);
  String info=null ;
  System.out.println("开始连接");
  while((info=br.readLine())!=null){
   System.out.println("我服务器，客户端说："+info);
   info=br.readLine();
  }
  socket.shutdownInput();
  //4.获取输出流
  OutputStream os=socket.getOutputStream();
  PrintWriter pw=new PrintWriter(os);
  pw.write("欢迎你!");
  pw.flush();
  //5.关闭资源
  pw.close();
  os.close();
  isr.close();
  is.close();
  br.close();
  socket.close();
  scoket1.close();
 } catch (IOException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 }
 
}  
}

运行结果：

服务器即将启动，等待客户端的链接***
开始连接
我服务器，客户端说：用户名：admin;密码:123