Configuring Remote Java Application debugger in Spring tool suite to debug maven based applications deployed in Tomcat

Create an environment variable

Variable Name: JPDA_OPTS
Variable Value: -agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n

Now in spring tool suite go to the Run -> Debug Configurations menu
Right click on the Remote Java Application menu in the right pane and click new.

Give this configuration a suitable name
In Connection type select Standard (Socket Attach)
In host enter localhost and on the port enter 8000
Now click on the source tab and use the add button to add the projects you want to debug.

Now deploy the project wars in the tomcat and start the tomcat server. Start server with following command from Windows command prompt
Tomcat_7_0_52\bin>catalina.bat jpda start


And then use the debug button to start your debugger (see the screen shot below). That's it...