I did not find any tutorial to create a maven project that uses Google App Engine and Spring and use Eclipse IDE. So, I thought I would document what I had done recently to create a Spring MVC project using Maven and deploys to Google App Engine; using Eclipse as IDE.
I am assuming you have Eclipse plugin for Maven (m2e) installed to Eclipse.
Creation of project:
We need to use maven plugin to create a new Google App Engine project. I used instructions to create using command line from here. I am sure we can use Eclipse maven project creation wizard as well.
Adding Spring dependencies:
To add Spring dependencies, add dependencies.
<!-- Spring Dependencies -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- Spring MVC framework -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
Tips:
- Till Spring 2.5.6, the framework used to provide a single all-encompassing dependency. From Spring 3.0.x on wards, that is not the case. So, we will have to include every dependency in pom.xml file.
- It is important to have same version for all Spring dependencies. If Spring dependencies don't have the same version, it gives out an error:
[INFO] java.lang.NoSuchFieldError: APPLICATION_CONTEXT_ID_PREFIX
[INFO] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:430)
[INFO] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:458)
[INFO] at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:339)
- Dependencies can be checked using this command:
mvn dependency:tree - When I was iterating through these steps multiple times, I found some old dependencies lingering around. If that happens, this command would clear things up:
mvn clean
Create web.xml:
If web.xml has not been created already, create it under
${project}/src/main/webapp/WEB-INFAdd DispatcherServlet to web.xml:
This is a standard Spring stuff you would do in any Spring MVC project. (I created MVC project, so I did this. It may or may not done in other cases) Also, depending on the name given to DispatcherServlet in web.xml, create <dispatcher-servlet-name>-servlet.xml xml file.
Deploying this application now will not work. Here are some steps I took to get rid of the errors:
- First, we need to clean up the maven project. Right click project -> Run As -> maven clean.
- Right click project -> Properties -> Project Facet -> Select "Dynamic Web Project".
- Again, Right click project -> Properties -> Deployment Assembly -> Add -> In popup, "Java Build Path Entries" -> Maven Dependencies -> Finish. All this does is to copy dependency jar to .../WEB-INF/lib.
Hopefully, this helps someone create a project without any errors.
Thanks to these links:
http://stackoverflow.com/a/12600686/1700184
http://stackoverflow.com/a/6083776/1700184
https://developers.google.com/appengine/docs/java/tools/maven#creating_a_new_maven_app_engine_project_using_skeleton-archetype
Thanks to these links:
http://stackoverflow.com/a/12600686/1700184
http://stackoverflow.com/a/6083776/1700184
https://developers.google.com/appengine/docs/java/tools/maven#creating_a_new_maven_app_engine_project_using_skeleton-archetype
