Limiting the size of JSON post request in Tomcat 8

I have tried to limit the post request size of api by setting maxpostsize in /conf/server.xml, but its not working,

Is there is any way to limit the size of json request in Tomcat?

this is my server.xml connector config

<Connector port="8080" protocol="HTTP/1.1" 
               connectionTimeout="20000" 
               redirectPort="8443" 
               maxPostSize="30000" />

Thanks in advance