Eclipse : Web Deployment Assembly & Maven depende

标准web工程在eclipse中利用m2eclipse插件添加依赖管理后，在部署过程中没有将依赖的jar包自动拷贝到/WEB-INF/lib中。
参考了一些朋友的做法手动执行

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1. mvn dependency:copy-dependencies -DoutputDirectory=src/main/webapp/WEB-INF/lib  -DincludeScope=runtime

命令将jar包拷贝到/WEB-INF/lib目录下。
这种做法固然可以，但是也会带来一些不便。
1、需要手动执行命令。
2、不能时时更新。

以下列出网上查找到的解决方法，m2eclipse plugin方式已验证通过。
通过验证eclipse版本：eclipse-jee-helios-SR2-win32
m2eclipse插件地址：http://m2eclipse.sonatype.org/sites/m2e
标准web工程通过m2eclipse添加依赖管理步骤：
1、“Maven ” –> “Enable dependency Management“

2、Web Deployment Assembly中添加maven dependencies

步骤如下图：

工程 -> 右键 -> preferences

.classpath文件中会有修改

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1. <classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER"/>

为

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1. <classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER">
2. <attributes>
3. <attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>
4. </attributes>
5. </classpathentry>

(执行“Maven ” –> “Update Project Configuration “未生效，故手动添加。必须deploy时候才会拷贝jar包到lib目录下，而非在更新maven依赖时候拷贝jar包。 )

以下为原文内容：

Eclipse : Web Deployment Assembly & Maven dependencies issue

Published: September 3, 2010 , Updated: September 3, 2010 , Author: mkyong

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Problem

In Eclipse 3.5 or early version, in order to deployed the Maven dependencies to the correct “/WEB-INF/lib ” folder, you have to configure the dependencies via “Java EE Module Dependencies”, and the updated “.classpath ” file will look like following :

File : “.classpath”, by Java EE Module Dependencies…

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1. ...  
2. <classpathentry kind="var" path="M2_REPO/javax/servlet/jsp/jsp-api/2.1/jsp-api-2.1.jar"   
3.    sourcepath="M2_REPO/javax/servlet/jsp/jsp-api/2.1/jsp-api-2.1-sources.jar">  
4.    <attributes>  
5.      <attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>  
6.    </attributes>  
7. </classpathentry>  
8. ...  

Since Eclipse 3.6, the “Java EE Module Dependencies” is replaced by “Web Deployment Assembly”, but you can do the same via the “Referenced Projects Classpath Entries”, however, it will update the “.classpath ” file as following :

File : “.classpath”, by Web Deployment Assembly…

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1. ...  
2. <classpathentry kind="var" path="M2_REPO/javax/servlet/jsp/jsp-api/2.1/jsp-api-2.1.jar"   
3.    sourcepath="M2_REPO/javax/servlet/jsp/jsp-api/2.1/jsp-api-2.1-sources.jar">  
4.    <attributes>  
5.      <attribute name="org.eclipse.jst.component.dependency" value="../"/>  
6.    </attributes>  
7. </classpathentry>  
8. ...  

Sadly, the default (value=”../”) makes all the Maven’s dependencies failed to deploy.

Solution

Not a big issue, you still can modify the (value=”../”) to (value=”/WEB-INF/lib”) manually, but it will get override every time you run a Maven build. No worry, there are still have two solutions :

1. WTP Support

Ignore the “Referenced Projects Classpath Entries” settings, instead, make the Maven supports WTP 2.0

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1. mvn eclipse:eclipse -Dwtpversion=2.0

It will generate a new file named “org.eclipse.wst.common.component “, under “settings ” folder, see a portion of this file :

File : “org.eclipse.wst.common.component”, by WTP

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1. ...  
2. <dependent-module archiveName="jsp-api-2.1.jar" deploy-path="/WEB-INF/lib"   
3.   handle="module:/classpath/var/M2_REPO/javax/servlet/jsp/jsp-api/2.1/jsp-api-2.1.jar">  
4.   <dependency-type>uses</dependency-type>  
5. </dependent-module>  
6. ...  

With WTP support, it helps to deploy the Maven dependencies to “/WEB-INF/lib ” folder correctly.

2. m2eclipse plugin

Install the m2eclipse , an Eclipse plugin to integrate Maven into the Eclipse IDE. After the installation, right click on the project folder, select “Maven ” –> “Update Project Configuration “, it will update the “.classpath ” file accordingly, see a snippet

File : “.classpath”, by m2eclipse

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1. ...  
2. <classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER">  
3.   <attributes>  
4.     <attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>  
5.   </attributes>  
6. </classpathentry>  
7. ...  

It helps to deploy the Maven dependencies correctly as well.

Reference

1. http://m2eclipse.sonatype.org/
2. http://www.mkyong.com/maven/maven-dependency-libraries-not-deploy-in-eclipse-ide/
3. http://www.eclipse.org/forums/index.php?t=msg&goto=542963&
4. http://www.eclipse.org/forums/index.php?t=msg&goto=543308&
5. http://tux2323.blogspot.com/2010/06/review-eclipse-helios-rc4.html

Eclipse : Web Deployment Assembly & Maven depende