Android编程实现基于局域网udp广播自动建立socket连接的方法

public class MainActivity extends Activity {  /*发送广播端的socket*/  private MulticastSocket ms;  /*发送广播的按钮*/  private Button sendUDPBrocast;  @Override  public void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   init();  }  /*初始化参数*/  public void init() {   setContentView(R.layout.main);   sendUDPBrocast = (Button) findViewById(R.id.send);   sendUDPBrocast.setOnClickListener(new SendUDPBrocastListener());   try {    /*创建socket实例*/    ms = new MulticastSocket();   } catch (Exception e) {    e.printStackTrace();   }  }  /**   * 单击按钮时，发送局域网广播   * */  class SendUDPBrocastListener implements OnClickListener{   @Override   public void onClick(View v) {    //发送的数据包，局网内的所有地址都可以收到该数据包    DatagramPacket dataPacket = null;    try {     ms.setTimeToLive(4);     //将本机的IP（这里可以写动态获取的IP）地址放到数据包里，其实server端接收到数据包后也能获取到发包方的IP的     byte[] data = "192.168.1.101".getBytes();     //224.0.0.1为广播地址     InetAddress address = InetAddress.getByName("224.0.0.1");     //这个地方可以输出判断该地址是不是广播类型的地址     System.out.println(address.isMulticastAddress());     dataPacket = new DatagramPacket(data, data.length, address,       8003);     ms.send(dataPacket);     ms.close();    } catch (Exception e) {     e.printStackTrace();    }   }  } } 

public class MainActivity extends Activity implements Runnable {  private MulticastSocket ds;  String multicastHost="224.0.0.1";  InetAddress receiveAddress;  @Override  public void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   setContentView(R.layout.main);   try {    ds = new MulticastSocket(8003);    receiveAddress=InetAddress.getByName(multicastHost);    ds.joinGroup(receiveAddress);    new Thread(this).start();   } catch (Exception e1) {    // TODO Auto-generated catch block    e1.printStackTrace();   }  }  @Override  public void run() {   // TODO Auto-generated method stub   byte buf[] = new byte[1024];   DatagramPacket dp = new DatagramPacket(buf, 1024);   while (true) {    try {     ds.receive(dp);     //Toast.makeText(this, new String(buf, 0, dp.getLength()), Toast.LENGTH_LONG);     System.out.println("client ip : "+new String(buf, 0, dp.getLength()));    } catch (Exception e) {     e.printStackTrace();    }   }  } }