How to prevent converting form POSTrequest to GET request using tools

I want to prevent converting Post request to get request using tools like Firefox web developer tools .

The url on the browser should not change at all from Post to get on click of submit button e.g :

http://localhost:7001/ApplicationWeb/login/Login.xhtml

to get url http://localhost:7001/ApplicationWeb/login/Login.xhtml?j_idt4=j_idt4&j_idt4%3AuserId=dsdsd&j_idt4%3Apassword=sdsdsdsd&j_idt4%3Asubmit=&javax.faces.ViewState=4039633169899650700%3A399774169313263205

it is a Java application using jsf ,spring ,hibernate

Please suggest how to prevent,very urgent