How to configure Eclipse build path to use Maven dependencies?

问题

I would like to take advantage of the features that Maven provides for managing dependencies in a project. My brief understanding of how Maven works is that it will aquire the JARs needed and then build the project with these libraries.

Currently I have a simple POM file set up as a test:

<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.jamesgoodwin.test</groupId>
  <artifactId>com.jamesgoodwin.test</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <build>
  </build>
  <dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>3.0.0.RELEASE</version>
        <type>jar</type>
        <scope>compile</scope>
    </dependency>
  </dependencies>
</project>

Usually when managing dependencies for a project I would add the project or JAR to the project build path and then be able to build my project..

But when using M2Eclipse the dependencies do are not automatically added to the build path. Is there somewhere I need to configure this to allow Eclipse to know that Maven is managing the dependencies?

回答1:

If you right-click on your project, there should be an option under "maven" to "enable dependency management". That's it.

回答2:

if you execute

mvn eclipse:clean

followed by

mvn eclipse:eclipse

if will prepare the eclipse .classpath file for you. That is, these commands are run against maven from the command line i.e. outside of eclipse.

回答3:

I'm assuming you are using m2eclipse as you mentioned it. However it is not clear whether you created your project under Eclipse or not so I'll try to cover all cases.

If you created a "Java" project under Eclipse (Ctrl+N > Java Project), then right-click the project in the Package Explorer view and go to Maven > Enable Dependency Management (depending on the initial project structure, you may have modify it to match the maven's one, for example by adding src/java to the source folders on the build path).
If you created a "Maven Project" under Eclipse (Ctrl+N > Maven Project), then it should be already "Maven ready".
If you created a Maven project outside Eclipse (manually or with an archetype), then simply import it in Eclipse (right-click the Package Explorer view and select Import... > Maven Projects) and it will be "Maven ready".

Now, to add a dependency, either right-click the project and select Maven > Add Dependency) or edit the pom manually.

PS: avoid using the maven-eclipse-plugin if you are using m2eclipse. There is absolutely no need for it, it will be confusing, it will generate some mess. No, really, don't use it unless you really know what you are doing.

回答4:

Add this to .classpath file ..

<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
    <attributes>
        <attribute name="maven.pomderived" value="true"/>
    </attributes>
</classpathentry>

Thx

回答5:

Right click on the project Configure > convert to Maven project

Then you can see all the Maven related Menu for you project.

回答6:

I did like this..

Right click on the project--> configure-->convert to maven project. Right click on the project-->maven-->add dependencies.

回答7:

In Eclipse (Mars) go to:

Project Properties --> Maven. Ensure that "Resolve dependencies from workspace projects" is disabled.

回答8:

I did not found the maven or configure menus but found the following button that solved my problem:

回答9:

When m2eclipse is installed properly, it should add dependencies automatically. However, you should generate the eclipse project files by entering:

mvn eclipse:m2eclipse

or, alternatively if you don't use m2eclipse:

mvn eclipse:eclipse

回答10:

I had a slight variation that caused some issues - multiple sub projects within one project. In this case I needed to go into each individual folder that contained a POM, execute the mvn eclipse:eclipse command and then manually copy/merge the classpath entries into my project classpath file.

回答11:

For newer Eclipse versions (>=Mars) right click on project > configure > convert to Maven project

回答12:

Adding my answers for a couple of reasons:

Somehow none of the answers listed directly resolved my problem.
I couldn't find "Enable dependency management" under Maven. I'm using Eclipse 4.4.2 build on Wed, 4 Feb 2015.

What helped me was another option under Maven called as "Update Project" and then when I click it this window opens which has a checkbox that says "Force update of Snapshot/Releases". The real purpose of this checkbox is different I know but somehow it resolved the dependencies issue.

回答13:

None of that solved my problem. but what I did was if click on the pom.xml, there is a tab at the bottom named dependencies. in this tab it is split into 2 section, one called dependencies and one called dependency management. select every thing in the dependency section and click add to be under the dependency management control. close and reopen your project.

回答14:

Maybe you could look into maven-eclipse-plugin instead of M2Eclipse.

There you basically add maven-eclipse-plugin configuration to your pom.xml and then execute mvn eclipse:eclipse which will generate the required .project and .classpath files for Eclipse. Then you'll have the correct build path in Eclipse.

回答15:

Make sure your POM follows the naming convention, and is named in lowercase lettering as pom.xml and NOT POM.xml.

In my case all was right, but Eclipse still complained when trying to Right-click and Update project configuration - told me that the POM could not be read. Changed the name to lowercase - pom.xml from POM.xml - and it worked.

回答16:

I met this issue too. When I add dependencies in the pom.xml, I checked in the local folder /Users/xyz/.m2/ and the jars are already downloaded there, but cann't added the the buildpath of the eclipse.

My eclipse Version: Mars.2 Release (4.5.2)

right click project > Maven > Enable Workspace Resolution

And this solved my issue.

回答17:

Typically, you can copy the .classpath file from a working project since there isn’t anything project specific here assuming you’re structured as a standard Maven project.