我开始使用 MulticastSocket 进行编码,尝试制作一个带有客户端和服务器的简单应用程序来发送消息。
我的服务器代码:
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.SocketException;
public class Servidor {
private static MulticastSocket ms;
public static void main(String[] args) throws IOException{
InetAddress sessAddr = InetAddress.getByName("224.2.76.24");
try{
sessAddr = InetAddress.getByName("224.2.76.24");
ms = new MulticastSocket(5500);
ms.joinGroup(sessAddr);
while (true)
{
byte[] mensaje = new byte[1024];
mensaje = "aa".getBytes();
DatagramPacket dp = new DatagramPacket(mensaje, mensaje.length,sessAddr,5500);
ms.send(dp);
}
}
catch (SocketException se) {
System.err.println(se);
}
ms.leaveGroup(sessAddr);
}
}
在客户端上是这样的:
package com.example;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.UnknownHostException;
import android.app.Activity;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.TextView;
public class ClienteMultiCast extends Activity {
/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
TextView Mensaje;
Mensaje =(TextView)findViewById(R.id.Mensaje);
InetAddress ia = null;
byte[] buffer = new byte[65535];
MulticastSocket ms = null;
int port = 5500;
try {
ia = InetAddress.getByName("224.2.76.24");
DatagramPacket dp = new DatagramPacket(buffer, buffer.length,ia,port);
ms = new MulticastSocket(port);
ms.joinGroup(ia);
while (true) {
ms.receive(dp);
String s = new String(dp.getData(),0,dp.getLength());
Mensaje.setText(s);
}
} catch (UnknownHostException e) {Mensaje.setText(e.getMessage());} catch (IOException e) {Mensaje.setText(e.getMessage()); }
try {
ms.leaveGroup(ia);
} catch (IOException e) {
Mensaje.setText(e.getMessage());
}
}
}
问题是当我启动两者时,什么也没有发生。客户端没有收到任何消息。
知道出了什么问题吗?
Diego,
默认情况下,Android WiFi 堆栈会过滤掉多播数据包。看一眼http://developer.android.com/reference/android/net/wifi/WifiManager.MulticastLock.html http://developer.android.com/reference/android/net/wifi/WifiManager.MulticastLock.html.
你需要一些类似的东西:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/* Turn off multicast filter */
MulticastLock mcastLock = new MulticastLock();
mcastLock.acquire();
/* Process Multicast Packets */
}
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