Java – Best way to debug Java web application packaged as a WAR using Eclipse and Maven

debuggingeclipsejavamaven-2

I've not built a Java web application before, but I have it complete enough to test and Maven is building my WAR file just fine. It is a multi-module Maven project and the dependent modules all have their JAR files in the WEB-INF/lib directory of the WAR.

So everything seems fine, but how to debug? I know how to (from the command line) run the WAR in Tomcat on my machine. I also think I know how to set up and run the Maven Jetty plugin from the command line as well. But how best to debug…with all the break points and variable inspection I love with Eclipse?

Is there some kind of launch configuration I should create, or do I attach the debugger remotely? Is there something in Eclipse that can help…like a plugin?

Best Answer

If you run your WAR with tomcat/jetty plugin pass debug options to the Maven:

export MAVEN_OPTS="-Xnoagent -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000" mvn tomcat:run

If you run your WAR using the regular Tomcat, just run it with JPDA (debugger) support enabled:

$TOMCAT_HOME/bin/catalina.sh jpda start

Default port for Tomcat 6 JPDA is 8000.

Now connect with the Eclipse (Debug -> Remote Java Application) to the port 8000 and enjoy your fine debugging session.

Related Solutions

Java – Maven Modules + Building a Single Specific Module

Any best practices here?

Use the Maven advanced reactor options, more specifically:

-pl, --projects
        Build specified reactor projects instead of all projects
-am, --also-make
        If project list is specified, also build projects required by the list

So just cd into the parent P directory and run:

mvn install -pl B -am

And this will build B and the modules required by B.

Note that you need to use a colon if you are referencing an artifactId which differs from the directory name:

mvn install -pl :B -am

As described here:

Define modules list which shall be build in Maven multiproject build

Java – How to get maven managed dependencies copied into war\web-inf\lib so I can run the GWT 2.0 app in debug mode within Eclipse

Running the gwt:eclipse goal will copy the maven dependencies into war/WEB-INF/lib. See the Eclipse Configuration section of the Eclipse IDE Integration documentation of the Maven GWT plugin for more details. Also have a look at this answer about Maven GWT 2.0 and Eclipse.

Best Answer

Related Solutions

Java – Maven Modules + Building a Single Specific Module

Java – How to get maven managed dependencies copied into war\web-inf\lib so I can run the GWT 2.0 app in debug mode within Eclipse

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