MSN

http://wenku.baidu.com/view/07eb395abe23482fb4da4c31.html   写的非常的好

http://apps.hi.baidu.com/share/detail/22908925    很不错

http://topic.csdn.net/u/20080313/16/55fa6b13-aa0d-4f48-8181-838924ab3cc4.html   代码实现

 

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