tomcat 7高版本上maxpostsize要设置为-1；高版本的TOMCAT 7要设置-1，否则设置=0的话，POST的方法是不起作用的； ​​
tomcat7.0.63之前：
maxPostSize The maximum size in bytes of the POST which will be handled by the container FORM URL parameter parsing. The limit can be disabled by setting this attribute to a value less than or equal to 0. If not specified, this attribute is set to 2097152 (2 megabytes).
设置为0和负数均可以代表不限制


tomcat7.0.63（包含）之后：
maxPostSize The maximum size in bytes of the POST which will be handled by the container FORM URL parameter parsing. The limit can be disabled by setting this attribute to a value less than zero. If not specified, this attribute is set to 2097152 (2 megabytes).
不可以设置为0，只能是负数代表不限制