import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
 
 
public class MyServer
{
 //定義保存所有Socket的ArrayList
 public static ArrayList<Socket> socketList 
 = new ArrayList<Socket>();
  public static void main(String[] args) 
 throws IOException
  {
    ServerSocket ss = new ServerSocket(8000);
 while(true)
 {
  //此行代碼會阻塞，將一直等待別人的連接
  Socket s = ss.accept();
  socketList.add(s);
  //每當客戶端連接后啟動一條ServerThread線程為該客戶端服務
  new Thread(new ServerThread(s)).start();
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.Socket;
 
 
 
//負責處理每個線程通信的線程類
public class ServerThread implements Runnable 
{
 //定義當前線程所處理的Socket
 Socket s = null;
 //該線程所處理的Socket所對應的輸入流
 BufferedReader br = null;
 public ServerThread(Socket s)
 throws IOException
 {
 this.s = s;
 //初始化該Socket對應的輸入流
 br = new BufferedReader(new InputStreamReader(
  s.getInputStream() , "utf-8"));  //②
 }
 public void run()
 {
 try
 {
  String content = null;
  //采用循環(huán)不斷從Socket中讀取客戶端發(fā)送過來的數據
  while ((content = readFromClient()) != null)
  {
  //遍歷socketList中的每個Socket，
  //將讀到的內容向每個Socket發(fā)送一次
  for (Socket s : MyServer.socketList)
  {
   OutputStream os = s.getOutputStream();
   os.write((content + "\n").getBytes("utf-8"));
  }
  }
 }
 catch (IOException e)
 {
  e.printStackTrace();
 }
 }
 //定義讀取客戶端數據的方法
 private String readFromClient()
 {
 try
 {
  return br.readLine(); 
 }
 //如果捕捉到異常，表明該Socket對應的客戶端已經關閉
 catch (IOException e)
 {
  //刪除該Socket。
  MyServer.socketList.remove(s);  //①
 }
 return null;
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 >
<LinearLayout 
 android:orientation="horizontal"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 >
<!-- 定義一個文本框，它用于接受用戶的輸入 -->
<EditText
 android:id="@+id/input" 
 android:layout_width="240px" 
 android:layout_height="wrap_content" 
 />
<Button
 android:id="@+id/send" 
 android:layout_width="fill_parent" 
 android:layout_height="wrap_content" 
 android:paddingLeft="8px"
 android:text="@string/send"
 />
</LinearLayout>
<!-- 定義一個文本框，它用于顯示來自服務器的信息 -->
<EditText
 android:id="@+id/show" 
 android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
 android:gravity="top"
 android:editable="false" 
 android:cursorVisible="false" 
 />
</LinearLayout>

package org.wwj.net;
 
import java.io.OutputStream;
import java.net.Socket;
 
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
 
public class MultiThreadClient extends Activity
{
 // 定義界面上的兩個文本框
 EditText input, show;
 // 定義界面上的一個按鈕
 Button send;
 OutputStream os;
 Handler handler;
 
 @Override
 public void onCreate(Bundle savedInstanceState)
 {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.main);
 input = (EditText) findViewById(R.id.input);
 send = (Button) findViewById(R.id.send);
 show = (EditText) findViewById(R.id.show);
 Socket s;
 handler = new Handler()
 {
  @Override
  public void handleMessage(Message msg)
  {
  // 如果消息來自于子線程
  if (msg.what == 0x123)
  {
   // 將讀取的內容追加顯示在文本框中
   show.append("\n" + msg.obj.toString());
  }
  }
 };
 try
 {
  s = new Socket("183.30.181.228 ", 8000);
  // 客戶端啟動ClientThread線程不斷讀取來自服務器的數據
  new Thread(new ClientThread(s, handler)).start(); // ①
  os = s.getOutputStream();
 }
 catch (Exception e)
 {
  e.printStackTrace();
 }
 send.setOnClickListener(new OnClickListener()
 {
  @Override
  public void onClick(View v)
  {
  try
  {
   // 將用戶在文本框內輸入的內容寫入網絡
   os.write((input.getText().toString() + "\r\n")
   .getBytes("utf-8"));
   // 清空input文本框
   input.setText("");
  }
  catch (Exception e)
  {
   e.printStackTrace();
  }
  }
 });
 }
}

package org.wwj.net;
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;
 
import android.os.Handler;
import android.os.Message;
 
public class ClientThread implements Runnable
{
 //該線程負責處理的Socket
 private Socket s;
 private Handler handler;
 //該線程所處理的Socket所對應的輸入流
 BufferedReader br = null;
 public ClientThread(Socket s , Handler handler)
 throws IOException
 {
 this.s = s;
 this.handler = handler;
 br = new BufferedReader(
  new InputStreamReader(s.getInputStream()));
 }
 public void run()
 {
 try
 {
  String content = null;
  //不斷讀取Socket輸入流中的內容。
  while ((content = br.readLine()) != null)
  {
  // 每當讀到來自服務器的數據之后，發(fā)送消息通知程序界面顯示該數據
  Message msg = new Message();
  msg.what = 0x123;
  msg.obj = content;
  handler.sendMessage(msg);
  }
 }
 catch (Exception e)
 {
  e.printStackTrace();
 }
 }
}