Create a Multi-Module Project in Eclipse

7 create a multi-module project in Eclipse

A multi-module project is, as its name suggests, a project that consists of multiple modules, where a module is a project. You can think of a multi-module project as a logical grouping of sub-projects. The packaging of a multi-module project is “pom”, since it consists of a pom.xml file but no artifact (jar, war, ear, etc).

The typical “maven” way to organize multi-module projects is to store them hierarchically, where your modules exist within your multi-module project. Your modules may even have more modules within them. However, the “Eclipse” way to organize projects is in a flat manner, where each module is a project located at the root level of your workspace.

In general, I prefer to do things the “maven” way, but as for project layouts, I prefer to do things the “Eclipse” way and use a flat structure where all projects are located at the same level and not nested within each other. I prefer the “Eclipse” way because it allows me to easily debug across modules when modules are dependent on other modules.

In my myproject pom.xml file, I set the packaging to “pom”. Next, I listed the modules as “../myapp_presentation”, “../myapp_service” and “../myapp_integration”. The “../” is used since the modules are Eclipse projects that are located at the same level as the “myproject” project. After this, I added commons io dependency to the “myproject” pom.xml file, since the commons io dependency is a common dependency shared by all modules. The “../myapp_presentation”, “../myapp_service” and “../myapp_integration” projects will now get the commons io dependency through inheritance.

Right click on the parent Project ie myproject ,create an maven module named myapp_integration and myappservice by following the below snapshot.

Create another maven module myapp_presentation as shown below

enter the filter javee6 and select select the artifactid webapp-javaee6 .click Next

change the package name.click Finish.

Myapp_presentation/pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>
<parent>
<artifactId>myproject</artifactId>
<groupId>in.com.pradeepit</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>myapp_presrentation</artifactId>
<packaging>war</packaging>
<name>myapp_presrentation</name>
<properties>
<endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-web-api</artifactId>
<version>6.0</version>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
<compilerArguments>
<endorseddirs>${endorsed.dir}</endorseddirs>
</compilerArguments>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.1.1</version>
<configuration>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
</plugins>
</build>
</project>

Notice each module pom.xml file contains parent tag ,which specifies parent project.

considering presentation module depends on service module ,add service module dependency to presenatation.

Updated pom.xml file .

/myapp_presentation/pom.xml

<?xml version="1.0" encoding="UTF-8"?> <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>
 <parent>
 <artifactId>myproject</artifactId>
 <groupId>in.com.pradeepit</groupId>
 <version>0.0.1-SNAPSHOT</version>
 </parent>
<artifactId>myapp_presentation</artifactId>
  <packaging>war</packaging>
  <name>myapp_presentation</name>
  <properties>
     <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties> 
   <dependencies>
   <dependency>
     <groupId>in.com.pradeepit</groupId>
     <artifactId>myapp_service</artifactId>
     <version>0.0.1-SNAPSHOT</version>
   </dependency>
   <dependency>
     <groupId>javax</groupId>
     <artifactId>javaee-web-api</artifactId>
      <version>6.0</version>
      <scope>provided</scope>
      </dependency>
   </dependencies>
   <build>
    <plugins>
    <plugin>
    <groupId>org.apache.maven.plugins</groupId>
     <artifactId>maven-compiler-plugin</artifactId>
    <version>2.3.2</version>
    <configuration>
      <source>1.6</source>
      <target>1.6</target>
        <compilerArguments>
          <endorseddirs>${endorsed.dir}</endorseddirs>
      </compilerArguments>
     </configuration>
    </plugin>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-war-plugin</artifactId>
      <version>2.1.1</version>
      <configuration>
       <failOnMissingWebXml>false</failOnMissingWebXml>
      </configuration>
     </plugin>
   </plugins>
  </build>
</project>

similarly service module depends on intregration module ,add integration module dependency to service module.

/myapp_service/pom.xml

<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>
<parent>
<groupId>in.com.pradeepit</groupId>
<artifactId>myproject</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>myapp_service</artifactId>
<dependencies>
  <dependency>
  <groupId>in.com.pradeepit</groupId>
  <artifactId>myapp_integration</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  </dependency>
 </dependencies>
</project>

Create a TestServlet class in presentation module and create reference of an service module ,in service module create reference of an integration module .

package in.com.pradeepit.service;
import in.com.pradeepit.dao.TestDao;
public class TestService
{
private TestDao testDao;
}

/myapp_presentation/src/main/java/in/com/pradeepit/servlet/TestServlet.java

package in.com.pradeepit.servlet;
import in.com.pradeepit.service.TestService;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class TestServlet
*/
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
private TestService testService;
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public TestServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
// TODO Auto-generated method stub
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
}

Create a common dependency in parent module myproject,this dependency will be available to all the submodules .

<?xml version="1.0" encoding="UTF-8"?>
<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>in.com.pradeepit</groupId>
<artifactId>myproject</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<modules>
<module>myapp_integration</module>
<module>myapp_service</module>
<module>myapp_presentation</module>
</modules>
<dependencies>
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>20030203.000550</version>
</dependency>
</dependencies>
</project>