Which servlet container are you using?
Tomcat, or something else?
Eclipse supports a number of different servlet containers, including Tomcat. If you go to Window / Preferences, and then to Server / Installed Runtimes, you can tell Eclipse where your servlet container is. If your project is a
Java web project, you can then deploy your application to the servlet container from Eclipse, and start the server in debugging mode from Eclipse. You can put breakpoints in the code of your JSPs, servlets or other classes in your webapp and debug it while it's running in the servlet container.