So I've definitely made some progress in the Maven, GWT, and Eclipse integration. Below would be a working sample starting from a GWT project started using the google eclipse plugin.
Prerequisites:
Eclipse 3.4
Google Eclipse Plugin
m2eclipse plugin
Create your gwt project:
Create a pom for your project:
Edit the pom to look like this (profiles and resource filtering are definitely not needed and can be removed) and add any other jars you may need for your project:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.demo.application</groupId>
<artifactId>Application</artifactId>
<version>0.0.1-SNAPSHOT</version>
<build>
<sourceDirectory>src</sourceDirectory>
<outputDirectory>war/WEB-INF/classes</outputDirectory>
<testSourceDirectory>test</testSourceDirectory>
<testOutputDirectory>target/test-classes</testOutputDirectory>
<resources>
<resource>
<filtering>true</filtering>
<directory>src</directory>
<includes>
<!--
This will include all files in the root source like
log4j.properties or applicationContext.xml
-->
<include>*.*</include>
<!--
This will include all files in client: 1. so this project can be
inherited by another project (needs java files) 2. will include
image files for image bundles
-->
<include>**/client/**</include>
<!-- This will include any css and image files in the public folder -->
<include>**/public/**</include>
<include>**/*.gwt.xml</include>
</includes>
</resource>
</resources>
<filters>
<!--
This tells which file to use for filtering, ${target} gets replaced
by the target property specified in your profile
-->
<filter>src/${target}.properties</filter>
</filters>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.5</source>
<target>1.5</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<!--
This plugin will copy dependencies into the right outputDirectory
-->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<configuration>
<outputDirectory>war/WEB-INF/lib</outputDirectory>
<overWriteReleases>true</overWriteReleases>
<overWriteSnapshots>true</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<version>2.3</version>
<configuration>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>google-maven-repository</id>
<name>Google Maven Repository</name>
<url>http://google-maven-repository.googlecode.com/svn/repository/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>com.google.appengine</groupId>
<artifactId>appengine-api-1.0-sdk</artifactId>
<version>1.2.1</version>
</dependency>
<dependency>
<groupId>com.google.appengine.orm</groupId>
<artifactId>datanucleus-appengine</artifactId>
<version>1.0.2.final</version>
</dependency>
<dependency>
<groupId>org.datanucleus</groupId>
<artifactId>datanucleus-core</artifactId>
<version>1.1.0</version>
<exclusions>
<exclusion>
<groupId>javax.transaction</groupId>
<artifactId>transaction-api</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.datanucleus</groupId>
<artifactId>datanucleus-jpa</artifactId>
<version>1.1.0</version>
</dependency>
<dependency>
<groupId>org.apache.geronimo.specs</groupId>
<artifactId>geronimo-jta_1.1_spec</artifactId>
<version>1.1.1</version>
</dependency>
<dependency>
<groupId>org.apache.geronimo.specs</groupId>
<artifactId>geronimo-jpa_3.0_spec</artifactId>
<version>1.1.1</version>
</dependency>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-servlet</artifactId>
<version>1.7.0</version>
</dependency>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-user</artifactId>
<version>1.7.0</version>
</dependency>
<dependency>
<groupId>javax.jdo</groupId>
<artifactId>jdo2-api</artifactId>
<version>2.3-ea</version>
<exclusions>
<exclusion>
<groupId>javax.transaction</groupId>
<artifactId>transaction-api</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>javax.transaction</groupId>
<artifactId>jta</artifactId>
<version>1.1</version>
</dependency>
</dependencies>
<profiles>
<profile>
<id>local</id>
<properties>
<target>local</target>
</properties>
</profile>
<profile>
<id>prod</id>
<properties>
<target>prod</target>
</properties>
</profile>
</profiles>
</project>
You'll have to install some of the jars into maven manually, they aren't really keeping up to date with these things. For the datanucleus-appengine-1.0.2.final.jar you have to use the one that was placed in the lib folder and run this command
mvn install:install-file -DgroupId=com.google.appengine.orm -DartifactId=datanucleus-appengine -Dversion=1.0.2.final -Dpackaging=jar -Dfile=/path/to/file
At this time I would enable maven (I got some error message but just hit ok):
If you are using profiles (you probably have an error in your project at this point) tell maven which active profile to use:
You'll get a message if you want maven to update your project, hit ok.
You're done, just ignore the warning about the missing gwt-servlet.jar, it will be there, just named differently.
now we just need to make an ant build.xml to make compiling, and deploying easy.
<project name="Application" default="java_compile" basedir=".">
<property file="./src/local.properties" />
<target name="java_compile" description="Java compile, filter resources, copy jars">
<echo>Make sure you have set up Maven Executable in ./src/local.properties</echo>
<echo>Your mvn exe is set to ${MAVEN_EXEC}</echo>
<!-- process-resources filters the files in the resources directory and copies them to target/classes -->
<!-- dependency:copy-dependencies copies the dependencies to the target/dependency folder -->
<delete dir="war/WEB-INF/lib" />
<exec taskname="compile project" dir="${basedir}" executable="${MAVEN_EXEC}">
<arg line="clean process-resources compile dependency:copy-dependencies -P local" />
</exec>
</target>
<path id="project.class.path">
<pathelement location="war/WEB-INF/classes" />
<pathelement location="${gwt.sdk}/gwt-user.jar" />
<fileset dir="${gwt.sdk}" includes="gwt-dev*.jar" />
<!-- Add any additional non-server libs (such as JUnit) -->
<fileset dir="war/WEB-INF/lib" includes="**/*.jar" />
</path>
<target name="gwt_compile" description="GWT compile to JavaScript" depends="java_compile">
<java failonerror="true" fork="true" classname="com.google.gwt.dev.Compiler">
<classpath>
<pathelement location="src" />
<path refid="project.class.path" />
</classpath>
<!-- add jvmarg -Xss16M or similar if you see a StackOverflowError -->
<jvmarg line="-Xmx512M" />
<!-- Additional arguments like -style PRETTY or -logLevel DEBUG -->
<arg value="com.demo.application.Application" />
</java>
</target>
<target name="create_war" depends="gwt_compile">
<echo>Creating the war file in target/Application.war</echo>
<zip destfile="target/Application.war" basedir="war" encoding="UTF8"/>
</target>
</project>
then our local.properties file needs to look something like this
gwt.sdk=/path/to/gwt-os-1.7.0
MAVEN_EXEC=/path/to/mvn.exe
Once that is done you need to run "ant java_compile" to copy the jars into the war/WEB-INF/lib folder. And every time you change the dependencies you'd want to run "ant java_compile"
Now if you ever want to simply create a war file without using eclipse you can just run "ant create_war"
