Launching Eclipse as a debugger

Answer 1

Here's an excellent article on remote debugging using Eclipse. They even have a section discussing Tomcat.

Answer 2

In general the Java program cannot tell if the JVM runs in debug mode or not, and there is no way to from your program to say that you always want to start a debugger HERE.

You can, however, tell the DEBUGGER that you want to have a breakpoint at a given location, and you will then enter the debugger when the program reaches that spot.

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EDIT: You will need to investigate your launcher to see how you can trick it to contain the options needed to enable debugging in the JVM. You may also see if jvisualvm can give you the information you need as it can attach to an unprepared Sun JVM.

Answer 3

Here's a link that I used to debug web apps on Tomcat. It goes through installing Eclipse, Tomcat and Java and then setting up Tomcat to run in Eclipse. Towards the bottom explains how to debug a servlet in Eclipse.

http://www.windofkeltia.com/j2ee/wtp-tutorial.html