### What problem were solved in this pull request?

Issue Number: close #151 

Problem:
当前在发送消息到客户端时，每个数据都会刷新socket buffer，效率很低

### What is changed and how it works?
实现BufferedWriter，通过buffered
writer将消息缓存在内存中，结果写完时或者buffer满时，才将结果真正的发送到客户端。

### Other information