android組播開發（2.3.7如下沒法正常接收組播）

android的組播真是夠麻煩的

1. 打開權限

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

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

2. 打開組播鎖，默認時，移動設備爲了省電是關閉的

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

3. 模擬器玩wifi仍是很痛苦的，莫名其妙的錯誤和失敗

4. 真機玩wifi組播也很要命，根據stackoverflow，android2.3.7如下的系統只能接收本身發送的組播消息，沒法接收其餘設備，包括移動設備，PC等發送的組播消息

如下是原文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.

手頭只有一臺老舊的索愛X8，android2.1， 接收組播異常

一臺小米1s，android4.0，能夠正常接收PC的組播