本文的负载均衡是基于中间件技术的，采用三层体系结构，位于中间件层的 负载均衡器负责将客户的请求根据数据库负载情况和负载均衡策略转发给最适合 处理的数据库中去。-This article is based on the load balancing middleware technology，using three—tier architecture．The middleware layer is responsible for transmitting client requests