How do I decide the dependencies for my maven project?

Question

As part of learning, this is my first "spring nature" maven project,

In specific, I would like to understand the approach to know the list of dependencies that are required for any "spring nature" maven project, that I work in future.

For this project, here are the list of 21 dependencies that were just dumped into pom.xml without being told about, which dependency to use when, in this training video at 20:50?

<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.example.j2eeapp</groupId>
  <artifactId>j2eeapplication</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <name>J2EE Applications Example</name>

  <repositories>
        <repository>
                <id>prime-repo</id>
                <name>PrimeFaces Maven Repository</name>
                <url>http://repository.primefaces.org</url>
        </repository>
  </repositories>

  <dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>4.1.8.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-validator</artifactId>
        <version>4.2.0.Final</version>
    </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.8.2</version>
            <scope>test</scope>
        </dependency>
        <dependency>
                <groupId>org.springframework.webflow</groupId>
                <artifactId>spring-webflow</artifactId>
                <version>2.3.1.RELEASE</version>
        </dependency>
        <dependency>
                <groupId>org.springframework.webflow</groupId>
                <artifactId>spring-faces</artifactId>
                <version>2.3.1.RELEASE</version>
        </dependency>
        <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-orm</artifactId>
                <version>3.1.1.RELEASE</version>
        </dependency>
        <dependency>
                <groupId>com.oracle</groupId>
                <artifactId>ojdbc14</artifactId>
                <version>10.2.0.1.0</version>
        </dependency>
        <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>1.2.16</version>
        </dependency>
        <dependency>
                <groupId>com.sun.faces</groupId>
                <artifactId>jsf-impl</artifactId>
                <version>2.1.10</version>
        </dependency>
        <dependency>
                <groupId>com.sun.facelets</groupId>
                <artifactId>jsf-facelets</artifactId>
                <version>1.1.14</version>
        </dependency>
        <dependency>
                <groupId>com.sun.faces</groupId>
                <artifactId>jsf-api</artifactId>
                <version>2.1.10</version>
        </dependency>
        <dependency>
                <groupId>commons-dbcp</groupId>
                <artifactId>commons-dbcp</artifactId>
                <version>20030825.184428</version>
        </dependency>
        <dependency>
                <groupId>org.slf4j</groupId>
                <artifactId>slf4j-log4j12</artifactId>
                <version>1.6.4</version>
        </dependency>
        <dependency>
                <groupId>javax.servlet</groupId>
                <artifactId>javax.servlet-api</artifactId>
                <version>3.0.1</version>
                <scope>provided</scope>
        </dependency>
        <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-tx</artifactId>
                <version>3.0.5.RELEASE</version>
        </dependency>
        <dependency>
                <groupId>xml-apis</groupId>
                <artifactId>xml-apis</artifactId>
                <version>1.3.02</version>
        </dependency>
        <dependency>
                <groupId>org.springframework.security</groupId>
                <artifactId>spring-security-web</artifactId>
                <version>3.1.3.RELEASE</version>
        </dependency>
        <dependency>
                <groupId>org.springframework.security</groupId>
                <artifactId>spring-security-config</artifactId>
                <version>3.1.3.RELEASE</version>
        </dependency>
        <dependency>
                <groupId>org.primefaces</groupId>
                <artifactId>primefaces</artifactId>
                <version>3.4</version>
        </dependency>
        <dependency>
                <groupId>cglib</groupId>
                <artifactId>cglib</artifactId>
                <version>2.2.2</version>
                <scope>runtime</scope>
        </dependency>
        <dependency>
                <groupId>org.hibernate</groupId>
                <artifactId>hibernate-entitymanager</artifactId>
                <version>4.1.8.Final</version>
        </dependency>

  </dependencies>
</project>

So, As of now, I do not have knowledge about bean/spring-webflow/hibernate etc...

What is the approach to know the dependencies required for my "spring nature" project?

Answer 1

Maven projects need dependencies instead of including jar files by build path.when you create a maven project, it requires the library files for the methods you use.you add the dependencies in pom.xml file and when you execute the maven build command the files are automatically downloaded from the internet and included in the project. You can control the files to download. you can just add dependencies of the library files you need in your source code.

you decide your dependencies by the methods you use in your source code. for example.you are using sql database in your project you must need a jar file for the sql driver. if you have a maven project you just have to add the dependency of the sql in pom.xml

Answer 2

Dependencies list depends on your project nature and usage of .jar relative files. Simple if you want to use sql in your project then you only need to add sql dependencies in your pom.xml and in the same way if you use junit in your project then you will add junit dependencies in pom.xml in this way after tag

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.8.2</version>
</dependency>

no need of extra dependencies that are not being used in project. Note that in maven dependencies repository you will see some extra dependencies. These are ones which maven used for itself or for other dependencies.

Answer 3

The "Spring nature" is related to how your IDE works with Spring plug-in. In eclipse, a "project nature" creates an association between the a project and a tool, plug-in, or feature set. By adding a nature to an eclipse project, you tell an eclipse plug-in that it is configured to use that project. By adding the "Spring Project Nature" to your project, you are enabling eclipse's spring plugin to work with your project.

Add dependencies on need basis. if you don't need hibernate or web-flow don't add it.Its like adding required toppings to your pizza. If you dont want mushroom, dont add it :)