https://blog.csdn.net/hasnext/article/details/53129245
https://www.cnblogs.com/afarmer/archive/2011/08/06/2129126.html
https://my.oschina.net/fajar/blog/524190
gem sources -a http://gems.ruby-china.com/
https://blog.csdn.net/hasnext/article/details/53129245
https://www.cnblogs.com/afarmer/archive/2011/08/06/2129126.html
https://my.oschina.net/fajar/blog/524190
gem sources -a http://gems.ruby-china.com/