Android MulticastSocket IP组播

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MulticastSocket 是对等的关系，也就是他们通过IP多点组播保留的地址来相互接收在这个组的Socket发送的消息

我写了一个例子，MultiSocketB是一个service,用于先接收再发送，MultiSocketA用于先发送再接收，完成这一动作后退出

记得要加使用网络的权限

<uses-permission android :name=" android .permission.INTERNET" />

先看MultiSocketA

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns: android ="http://schemas. android .com/apk/res/ android "
package="com.example.multicastsocketsend"
android :versionCode="1"
android :versionName="1.0" >
<uses-permission android :name=" android .permission.INTERNET" />
<uses-sdk
android :minSdkVersion="8"
android :targetSdkVersion="17" />
<application
android :allowBackup="true"
android :icon="@drawable/ic_launcher"
android :label="@string/app_name"
android :theme="@style/AppTheme" >
<activity
android :name="com.example.multicastsocketsend.MultiSocketA"
android :label="@string/app_name" >
<intent-filter>
<action android :name=" android .intent.action.MAIN" />
<category android :name=" android .intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

package com.example.multicastsocketsend;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net. MulticastSocket ;
import android .app.Activity;
import android .os.Bundle;
import android .os.Handler;
import android .os.HandlerThread;
import android .util.Log;
/**
* @author lijinwei
* 本应用用于实现IP多点广播
* 若要使用多点广播时，则需要让一个数据报标有一组目标主机地址，当数据报发出后，整个组的所有主机都能收到该数据报。
* IP多点广播（或多点发送）实现了将单一信息发送到多个接收者的广播，其思想是设置一组特殊网络地址作为多点广播地址，每一个多点广播地址都被看做一个组，
* 当客户端需要发送、接收广播信息时，加入到该组即可。
*/
public class MultiSocketA extends Activity {
protected static final String TAG = "MultiSocketA";
private Handler mHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//通过Handler启动线程
HandlerThread handlerThread = new HandlerThread("MultiSocketA");
handlerThread.start();
mHandler = new Handler(handlerThread.getLooper());
mHandler.post(mRunnable);
}
private Runnable mRunnable = new Runnable() {
public void run() {
Log.v(TAG, "run...");
try {
sendMultiBroadcast();
} catch (Exception e) {
e.printStackTrace();
}
}
private void sendMultiBroadcast() throws IOException {
Log.v(TAG, "sendMultiBroadcast...");
/*
* 实现多点广播时， MulticastSocket 类是实现这一功能的关键，当 MulticastSocket 把一个DatagramPacket发送到多点广播IP地址，
* 该数据报将被自动广播到加入该地址的所有 MulticastSocket 。 MulticastSocket 类既可以将数据报发送到多点广播地址，
* 也可以接收其他主机的广播信息
*/
MulticastSocket socket = new MulticastSocket (8600);
//IP协议为多点广播提供了这批特殊的IP地址，这些IP地址的范围是224.0.0.0至239.255.255.255
InetAddress address = InetAddress.getByName("224.0.0.1");
/*
* 创建一个 MulticastSocket 对象后，还需要将该 MulticastSocket 加入到指定的多点广播地址，
* MulticastSocket 使用jionGroup()方法来加入指定组；使用leaveGroup()方法脱离一个组。
*/
socket.joinGroup(address);
/*
* 在某些系统中，可能有多个网络接口。这可能会对多点广播带来问题，这时候程序需要在一个指定的网络接口上监听，
* 通过调用setInterface可选择 MulticastSocket 所使用的网络接口；
* 也可以使用getInterface方法查询 MulticastSocket 监听的网络接口。
*/
//socket.setInterface(address);
DatagramPacket packet;
//发送数据包
Log.v(TAG, "send packet");
byte[] buf = "Hello I am MultiSocketA".getBytes();
packet = new DatagramPacket(buf, buf.length, address, 8601);
socket.send(packet);
//接收数据
Log.v(TAG, "receiver packet");
byte[] rev = new byte[512];
packet = new DatagramPacket(rev, rev.length);
socket.receive(packet);
Log.v(TAG, "get data = " + new String(packet.getData()).trim()); //不加trim，则会打印出512个byte，后面是乱码
//退出组播
socket.leaveGroup(address);
socket.close();
}
};
}

再看MultiSocketB

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns: android ="http://schemas. android .com/apk/res/ android "
package="com.example.multicastsocketreceiver"
android :versionCode="1"
android :versionName="1.0" >
<uses-permission android :name=" android .permission.INTERNET" />
<uses-sdk
android :minSdkVersion="8"
android :targetSdkVersion="17" />
<application
android :allowBackup="true"
android :icon="@drawable/ic_launcher"
android :label="@string/app_name"
android :theme="@style/AppTheme" >
<activity
android :name="com.example.multicastsocketreceiver.MainActivity"
android :label="@string/app_name" >
<intent-filter>
<action android :name=" android .intent.action.MAIN" />
<category android :name=" android .intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android :name=".MultiSocketB" />
</application>
</manifest>

package com.example.multicastsocketreceiver;
import android .os.Bundle;
import android .app.Activity;
import android .content.Intent;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Intent intent = new Intent();
intent.setClass(this, MultiSocketB.class);
this.startService(intent);
}
}

package com.example.multicastsocketreceiver;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net. MulticastSocket ;
import android .app.Service;
import android .content.Intent;
import android .os.Handler;
import android .os.HandlerThread;
import android .os.IBinder;
import android .util.Log;
public class MultiSocketB extends Service {
protected static final String TAG = "MultiSocketB";
private Handler mHandler;
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onCreate() {
super.onCreate();
Log.v(TAG, "onCreate");
// 通过Handler启动线程
HandlerThread handlerThread = new HandlerThread("MultiSocketB");
handlerThread.start();
mHandler = new Handler(handlerThread.getLooper());
mHandler.post(mRunnable);
}
private Runnable mRunnable = new Runnable() {
public void run() {
Log.v(TAG, "run...");
try {
receiveMultiBroadcast();
} catch (Exception e) {
e.printStackTrace();
}
}
};
protected void receiveMultiBroadcast() throws IOException {
Log.v(TAG, "receiveMultiBroadcast...");
MulticastSocket socket = new MulticastSocket (8601);
InetAddress address = InetAddress.getByName("224.0.0.1");
socket.joinGroup(address);
DatagramPacket packet;
// 接收数据
Log.v(TAG, "receiver packet");
byte[] rev = new byte[512];
packet = new DatagramPacket(rev, rev.length);
socket.receive(packet);
String receiver = new String(packet.getData()).trim(); //不加trim，则会打印出512个byte，后面是乱码
Log.v(TAG, "get data = " + receiver);
//发送数据包
Log.v(TAG, "send packet");
String process_receiver = "I am MultiSocketB, I got " + receiver;
byte[] buf = process_receiver.getBytes();
packet = new DatagramPacket(buf, buf.length, address, 8600);
socket.send(packet);
//退出组播
socket.leaveGroup(address);
socket.close();
}
}