public class SocketServer {
 public static void main(String[] args) throws IOException {
  //1.創(chuàng)建一個(gè)服務(wù)器端Socket，即ServerSocket，指定綁定的端口，并監(jiān)聽(tīng)此端口
  ServerSocket serverSocket = new ServerSocket(12345);
  InetAddress address = InetAddress.getLocalHost();
  String ip = address.getHostAddress();
  Socket socket = null;
  //2.調(diào)用accept()等待客戶(hù)端連接
  System.out.println("~~~服務(wù)端已就緒，等待客戶(hù)端接入~，服務(wù)端ip地址: " + ip);
  socket = serverSocket.accept();
  //3.連接后獲取輸入流，讀取客戶(hù)端信息
  InputStream is=null;
  InputStreamReader isr=null;
  BufferedReader br=null;
  OutputStream os=null;
  PrintWriter pw=null;
  is = socket.getInputStream();  //獲取輸入流
  isr = new InputStreamReader(is,"UTF-8");
  br = new BufferedReader(isr);
  String info = null;
  while((info=br.readLine())!=null){//循環(huán)讀取客戶(hù)端的信息
   System.out.println("客戶(hù)端發(fā)送過(guò)來(lái)的信息" + info);
  }
  socket.shutdownInput();//關(guān)閉輸入流
  socket.close();
 }
}

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  Button btn_accept = (Button) findViewById(R.id.btn_accept);
  btn_accept.setOnClickListener(this);
 }

 @Override
 public void onClick(View v) {
  new Thread() {
   @Override
   public void run() {
    try {
     acceptServer();
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  }.start();
 }

 private void acceptServer() throws IOException {
  //1.創(chuàng)建客戶(hù)端Socket，指定服務(wù)器地址和端口
  Socket socket = new Socket("172.16.2.54", 12345);
  //2.獲取輸出流，向服務(wù)器端發(fā)送信息
  OutputStream os = socket.getOutputStream();//字節(jié)輸出流
  PrintWriter pw = new PrintWriter(os);//將輸出流包裝為打印流
  //獲取客戶(hù)端的IP地址
  InetAddress address = InetAddress.getLocalHost();
  String ip = address.getHostAddress();
  pw.write("客戶(hù)端：~" + ip + "~ 接入服務(wù)器！！");
  pw.flush();
  socket.shutdownOutput();//關(guān)閉輸出流
  socket.close();
 }
}

public class Server {
 //定義相關(guān)的參數(shù),端口,存儲(chǔ)Socket連接的集合,ServerSocket對(duì)象
 //以及線程池
 private static final int PORT = 12345;
 private List<Socket> mList = new ArrayList<Socket>();
 private ServerSocket server = null;
 private ExecutorService myExecutorService = null;
 
 
 public static void main(String[] args) {
  new Server();
 }

 public Server()
 {
  try
  {
   server = new ServerSocket(PORT);
   //創(chuàng)建線程池
   myExecutorService = Executors.newCachedThreadPool();
   System.out.println("服務(wù)端運(yùn)行中...\n");
   Socket client = null;
   while(true)
   {
    client = server.accept();
    mList.add(client);
    myExecutorService.execute(new Service(client));
   }
   
  }catch(Exception e){e.printStackTrace();}
 }
 
 class Service implements Runnable
 {
  private Socket socket;
  private BufferedReader in = null;
  private String msg = "";
  
  public Service(Socket socket) {
   this.socket = socket;
   try
   {
    in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
     msg = "用戶(hù):" +this.socket.getInetAddress() + "~加入了聊天室" 
       +"當(dāng)前在線人數(shù):" +mList.size(); 
    this.sendmsg();
   }catch(IOException e){e.printStackTrace();}
  }
  
  
  
  @Override
  public void run() {
   try{
    while(true)
    {
     if((msg = in.readLine()) != null)
     {
      if(msg.equals("bye"))
      {
       System.out.println("~~~~~~~~~~~~~");
       mList.remove(socket);
       in.close();
       msg = "用戶(hù):" + socket.getInetAddress() 
         + "退出:" +"當(dāng)前在線人數(shù):"+mList.size(); 
       socket.close(); 
       this.sendmsg(); 
       break;
      }else{
       msg = socket.getInetAddress() + " 說(shuō): " + msg; 
       this.sendmsg(); 
      }
     }
    }
   }catch(Exception e){e.printStackTrace();}
  }
  
  //為連接上服務(wù)端的每個(gè)客戶(hù)端發(fā)送信息
  public void sendmsg()
  {
   System.out.println(msg);
   int num = mList.size();
   for(int index = 0;index < num;index++)
   {
    Socket mSocket = mList.get(index); 
    PrintWriter pout = null; 
    try { 
     pout = new PrintWriter(new BufferedWriter( 
       new OutputStreamWriter(mSocket.getOutputStream(),"UTF-8")),true); 
     pout.println(msg); 
    }catch (IOException e) {e.printStackTrace();} 
   }
  }
  
 }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical" >

 <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="小豬簡(jiǎn)易聊天室" />
 <TextView
  android:id="@+id/txtshow"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  />
 <EditText
  android:id="@+id/editsend"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  />
 <Button
  android:id="@+id/btnsend"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:text="發(fā)送"
  />
</LinearLayout>

public class MainActivity extends AppCompatActivity implements Runnable {

 //定義相關(guān)變量,完成初始化
 private TextView txtshow;
 private EditText editsend;
 private Button btnsend;
 private static final String HOST = "172.16.2.54";
 private static final int PORT = 12345;
 private Socket socket = null;
 private BufferedReader in = null;
 private PrintWriter out = null;
 private String content = "";
 private StringBuilder sb = null;

 //定義一個(gè)handler對(duì)象,用來(lái)刷新界面
 public Handler handler = new Handler() {
  public void handleMessage(Message msg) {
   if (msg.what == 0x123) {
    sb.append(content);
    txtshow.setText(sb.toString());
   }
  }

  ;
 };


 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  sb = new StringBuilder();
  txtshow = (TextView) findViewById(R.id.txtshow);
  editsend = (EditText) findViewById(R.id.editsend);
  btnsend = (Button) findViewById(R.id.btnsend);

  //當(dāng)程序一開(kāi)始運(yùn)行的時(shí)候就實(shí)例化Socket對(duì)象,與服務(wù)端進(jìn)行連接,獲取輸入輸出流
  //因?yàn)?.0以后不能再主線程中進(jìn)行網(wǎng)絡(luò)操作,所以需要另外開(kāi)辟一個(gè)線程
  new Thread() {

   public void run() {
    try {
     socket = new Socket(HOST, PORT);
     in = new BufferedReader(new InputStreamReader(socket.getInputStream(), "UTF-8"));
     out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
       socket.getOutputStream())), true);
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  }.start();

  //為發(fā)送按鈕設(shè)置點(diǎn)擊事件
  btnsend.setOnClickListener(new View.OnClickListener() {

   @Override
   public void onClick(View v) {
    String msg = editsend.getText().toString();
    if (socket.isConnected()) {
     if (!socket.isOutputShutdown()) {
      out.println(msg);
     }
    }
   }
  });
  new Thread(MainActivity.this).start();
 }

 //重寫(xiě)run方法,在該方法中輸入流的讀取
 @Override
 public void run() {
  try {
   while (true) {
    if (socket.isConnected()) {
     if (!socket.isInputShutdown()) {
      if ((content = in.readLine()) != null) {
       content += "\n";
       handler.sendEmptyMessage(0x123);
      }
     }
    }
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
}

public class UPDServer {
 public static void main(String[] args) throws IOException {
  /*
   * 接收客戶(hù)端發(fā)送的數(shù)據(jù)
   */
  // 1.創(chuàng)建服務(wù)器端DatagramSocket，指定端口
  DatagramSocket socket = new DatagramSocket(12345);
  // 2.創(chuàng)建數(shù)據(jù)報(bào)，用于接收客戶(hù)端發(fā)送的數(shù)據(jù)
  byte[] data = new byte[1024];// 創(chuàng)建字節(jié)數(shù)組，指定接收的數(shù)據(jù)包的大小
  DatagramPacket packet = new DatagramPacket(data, data.length);
  // 3.接收客戶(hù)端發(fā)送的數(shù)據(jù)
  System.out.println("****服務(wù)器端已經(jīng)啟動(dòng)，等待客戶(hù)端發(fā)送數(shù)據(jù)");
  socket.receive(packet);// 此方法在接收到數(shù)據(jù)報(bào)之前會(huì)一直阻塞
  // 4.讀取數(shù)據(jù)
  String info = new String(data, 0, packet.getLength());
  System.out.println("我是服務(wù)器，客戶(hù)端說(shuō)：" + info);

  /*
   * 向客戶(hù)端響應(yīng)數(shù)據(jù)
   */
  // 1.定義客戶(hù)端的地址、端口號(hào)、數(shù)據(jù)
  InetAddress address = packet.getAddress();
  int port = packet.getPort();
  byte[] data2 = "歡迎您!".getBytes();
  // 2.創(chuàng)建數(shù)據(jù)報(bào)，包含響應(yīng)的數(shù)據(jù)信息
  DatagramPacket packet2 = new DatagramPacket(data2, data2.length, address, port);
  // 3.響應(yīng)客戶(hù)端
  socket.send(packet2);
  // 4.關(guān)閉資源
  socket.close();
 }
}

public class UDPClient {
 public static void main(String[] args) throws IOException {
  /*
   * 向服務(wù)器端發(fā)送數(shù)據(jù)
   */
  // 1.定義服務(wù)器的地址、端口號(hào)、數(shù)據(jù)
  InetAddress address = InetAddress.getByName("localhost");
  int port = 8800;
  byte[] data = "用戶(hù)名：admin;密碼：123".getBytes();
  // 2.創(chuàng)建數(shù)據(jù)報(bào)，包含發(fā)送的數(shù)據(jù)信息
  DatagramPacket packet = new DatagramPacket(data, data.length, address, port);
  // 3.創(chuàng)建DatagramSocket對(duì)象
  DatagramSocket socket = new DatagramSocket();
  // 4.向服務(wù)器端發(fā)送數(shù)據(jù)報(bào)
  socket.send(packet);

  /*
   * 接收服務(wù)器端響應(yīng)的數(shù)據(jù)
   */
  // 1.創(chuàng)建數(shù)據(jù)報(bào)，用于接收服務(wù)器端響應(yīng)的數(shù)據(jù)
  byte[] data2 = new byte[1024];
  DatagramPacket packet2 = new DatagramPacket(data2, data2.length);
  // 2.接收服務(wù)器響應(yīng)的數(shù)據(jù)
  socket.receive(packet2);
  // 3.讀取數(shù)據(jù)
  String reply = new String(data2, 0, packet2.getLength());
  System.out.println("我是客戶(hù)端，服務(wù)器說(shuō)：" + reply);
  // 4.關(guān)閉資源
  socket.close();
 }
}