wdiahu issues

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                                            wdiahu

The server-side handler can take singleton mode to optimize; Also added bus handler (IMHandler) and reduced the number of handlers in ChannelPipeline

服务端handler出去编解码器之外，都是无状态handler，是否可以考虑以单例模式创建，而不是每次建立连接都重复创建，节省资源？

> - ### PR Title > > Auto-generate SELECT fields based on struct type > > ### PR Body > > #### 1. Motivation > > > When developing the...