android组播开发（2.3.7以下无法正常接收组播）

android的组播真是够麻烦的

1. 打开权限

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

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

2. 打开组播锁，默认时，移动设备为了省电是关闭的

WifiManager wifi = (WifiManager)getSystemService( Context.WIFI_SERVICE );
if(wifi != null)
{
MulticastLock mcLock = wifi.createMulticastLock("mylock");
mcLock.acquire();
...

3. 模拟器玩wifi还是很痛苦的，莫名其妙的错误和失败

4. 真机玩wifi组播也很要命，根据stackoverflow，android2.3.7以下的系统只能接收自己发送的组播消息，无法接收其他设备，包括移动设备，PC等发送的组播消息

以下是原文http://stackoverflow.com/questions/3623143/multicast-on-android-2-2

I've been doing a bit of research into this, and I believe it is a problem with Android in general, and fixed in or around Android 2.3.7.

It's a bit too anecdotal, but here's what I tested:

• HTC Desire, 2.2, stock: fail

• HTC Desire, 2.3.7, CyanogenMod: success

• Motorola Milestone, 2.1-update1: fail

• HTC Desire S, 2.3.3: fail

• Acer Iconia A501, 3.2.1: success

• Samsung something, 2.3.3: fail

• HTC Legend, 2.2 I think: fail

When I say 'fail', in fact they were all able to send multicast messages to the 'success' devices, but never receive anything back except their own messages - as jldupont describes.

手头只有一台老旧的索爱X8，android2.1， 接收组播异常

一台小米1s，android4.0，可以正常接收PC的组播