写了两个网络的java小程序 报错说connetion reset! 求教！?报错

package server;

import java.io.*;
import java.io.IOException;
import java.net.*;

class Server {
 public static void main(String[] args) {
  try {
   ServerSocket ss=new ServerSocket(8888);
   Socket s1=ss.accept();
   System.out.println("Client conneted!");
   BufferedReader br=new BufferedReader(
     new InputStreamReader(s1.getInputStream()));
   System.out.println(br.readLine());
 
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

package client;

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

public class Client {
 public static void main(String[] args)  {
  try {
   Socket s=new Socket("127.0.0.1",8888);
   BufferedWriter br=new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
   BufferedReader br1=new BufferedReader(
     new InputStreamReader(System.in));
   String str=br1.readLine();
   br.write(str);
   
  } catch (UnknownHostException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

以上一个client 一个server 功能就是两者连接后从client那里输入一个字符串然后再server那里输出

但是当我在client处输入一个字符串并按回车后这样报错

java.net.SocketException: Connection reset
 at java.net.SocketInputStream.read(SocketInputStream.java:168)
 at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:264)
 at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:306)
 at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:158)
 at java.io.InputStreamReader.read(InputStreamReader.java:167)
 at java.io.BufferedReader.fill(BufferedReader.java:136)
 at java.io.BufferedReader.readLine(BufferedReader.java:299)
 at java.io.BufferedReader.readLine(BufferedReader.java:362)
 at server.Server.main(Server.java:15)

中间哪里出问题了呢？ 大神何在？