创建多个工程

How do I build more than one project at once?
The concept of dealing with multiple modules is built in to Maven 2.0. In this section, we will show how to build the WAR above, and include the previous JAR as well in one step.

Firstly, we need to add a parent pom.xml file in the directory above the other two, so it should look like this:

+- pom.xml
+- my-app
| +- pom.xml
| +- src
|   +- main
|     +- java
+- my-webapp
| +- pom.xml
| +- src
|   +- main
|     +- webapp
The POM file you'll create should contain the following:

<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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.mycompany.app</groupId>
  <version>1.0-SNAPSHOT</version>
  <artifactId>app</artifactId>
  <packaging>pom</packaging>
  <modules>
    <module>my-app</module>
    <module>my-webapp</module>
  </modules>
</project>
We'll need a dependency on the JAR from the webapp, so add this to my-webapp/pom.xml:

  ...
  <dependencies>
    <dependency>
      <groupId>com.mycompany.app</groupId>
      <artifactId>my-app</artifactId>
      <version>1.0-SNAPSHOT</version>
    </dependency>
    ...
  </dependencies>
Finally, add the following <parent> element to both of the other pom.xml files in the subdirectories:

<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/xsd/maven-4.0.0.xsd">
  <parent>
    <groupId>com.mycompany.app</groupId>
    <artifactId>app</artifactId>
    <version>1.0-SNAPSHOT</version>
  </parent>
  ...
Now, try it... from the top level directory, run:

mvn clean install
The WAR has now been created in my-webapp/target/my-webapp.war, and the JAR is included:

$ jar tvf my-webapp/target/my-webapp-1.0-SNAPSHOT.war
   0 Fri Jun 24 10:59:56 EST 2005 META-INF/
222 Fri Jun 24 10:59:54 EST 2005 META-INF/MANIFEST.MF
   0 Fri Jun 24 10:59:56 EST 2005 META-INF/maven/
   0 Fri Jun 24 10:59:56 EST 2005 META-INF/maven/com.mycompany.app/
   0 Fri Jun 24 10:59:56 EST 2005 META-INF/maven/com.mycompany.app/my-webapp/
3239 Fri Jun 24 10:59:56 EST 2005 META-INF/maven/com.mycompany.app/my-webapp/pom.xml
   0 Fri Jun 24 10:59:56 EST 2005 WEB-INF/
215 Fri Jun 24 10:59:56 EST 2005 WEB-INF/web.xml
123 Fri Jun 24 10:59:56 EST 2005 META-INF/maven/com.mycompany.app/my-webapp/pom.properties
  52 Fri Jun 24 10:59:56 EST 2005 index.jsp
   0 Fri Jun 24 10:59:56 EST 2005 WEB-INF/lib/
2713 Fri Jun 24 10:59:56 EST 2005 WEB-INF/lib/my-app-1.0-SNAPSHOT.jar