1 在tomcat服务器当中,4**表示客户端请求错误,5**表示程序错误
2.request知识参考网址:http://wenku.baidu.com/link?url=wYwTGk8XKrLzANqWFC6i0Hgg5V19_5O3OJ_d1Jrdcp28YiLomplUBQXH3SqqFHqabIQ_1qVH_7x-4obUXKEocrXRbUDy3BULPiNulWyueHa
http://www.360doc.com/content/13/0227/10/6161903_268166561.shtml