https://www.cnblogs.com/TextEditor/p/5527124.html
http://www.codesnippet.info/Article/Index?ArticleId=00000038
http://www.jianshu.com/p/4140be00d4e3
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http://www.doc88.com/p-6941533630446.html
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http://blog.sina.com.cn/s/blog_6827755d0101b4c1.html
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