如何从jsp页面发送json String到Spring mvc控制器

I am trying to pass a simple json string to my controller,but it is not getting at there.I have a lot of other fields like inserting deleting etc inside my controller code,all of them will works perfectly,except this Json receiving.I tried a lot but not able to find out.I checked the path given and its correct.Is anything wrong with my controller code?Any help will be highly appreciableI am trying to pass a simple json string to my