Android MulticastSocket IP组播

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();

}

}