tutorial See a tutorial here: 5 Eclipse.

As an instance we explain how to configure GeoServer and Tomcat with Eclipse IDE.

Lounching Tomcat from Eclipse and debugging GeoServer

You can even configure Tomcat to be started by Eclipse in order to live-debug GeoServer without recompile it everytime.

Go to menu Run > Run...

A Wizard will open up. Here you will see on left a "Configurations" panel and on right hand side some tabs.
In "Configuration" panel, right click on "Java Applications" and select "New" in menu.

A new entry called "New_configuration" will be created. Rename it as you wish.

Now in the right hand side tabs, in "Main" tab, enter your "Project".

Enter "Main class" entry as "org.apache.catalina.startup.Bootstrap".

Also check on "Include external jarswhen searching for a main class" check box.

Now move on to "Arguments" tab.
Here for "Program Arguments", enter the value as "start".

For "VM Arguments", enter the following:
-Dcatalina.base="<path to Tomcat dir>"
-Dcatalina.home="<path to Tomcat dir>"
-Djava.io.tmpdir="<path to Tomcat dir>/temp"
-Xmx500m

Enter "Working Directory" as your project name.

Move on to "JRE" tab. Keep the default JRE setting here.

Move on to "Classpath" tab, remove everything and click on "Restore Default Entries".

Now leave the "Bootstrap Entries" as it is.

In "User Entries", add the following jars from CATALINA_HOME/bin directory.
bootstrap.jar, commons-daemon.jar, commons-logging-api.jar, and your project

Click on Apply Button. and Run.