I had shared a basic understanding of maven sometime back.
Here I will try to get into some more details.
As mentioned earlier we need a pom file for any maven project. POM stands for Project Object Model. It contains configuration details for the project.
To start with we provide basic info such as
group id: shows project group, say finance
artifact id: within group we will have a unique project name as artifact id say payroll
version: It is the release version e.g. 1.0 or 2.1.2 etc.
repositories: where all the jars, plugins and other artifacts are stored and used by maven.
Type of repositories
Local Repository: A folder on local machine where all the dependencies are stored. Maven by default creates the repo in user/home directory, this path can be overridden by “localrepository” tag in POM.
Central repository: This is by default provided by maven, and has most of the common jars. No need for a separate configuration for this.
Remote Repository: Developer has an option to provide a repository explicitly, so if a give dependency is not found in central repository, it will be fetched from remote repository.
Dependencies: All the Jar files on which project is dependent and will be downloaded before the build.
There might be a requirement to let the war file include all maven dependencies (jars downloaded through maven) to avoid adding them manually to server, especialy while development time.
Right click project -> properties-> Deployment Assembly-> add ->build path entries->maven dependencies
Official definition of Maven states “Apache Maven is a software project management and comprehension tool.” For me, Maven is a build tool, that helps me manage dependencies as well. The advantage I get over Ant tool, is that it not only manages dependencies, but also downloads them automatically. Also I need not worry about transitive depeendies, that is if a jar I need for my project is inturn dependent on other jars, maven will take care of it for me.
Getting started: Using maven with Eclipse is simple. Eclipse comes with embedded maven so you need not worry about downloading or installing.
In New->Project, you can select Maven Project. It will ask you to select Archtype. An Archtype is predefine project templates. For example you can use Spring project, you can choose spring archtype. This will help you getting started by providing a sample template project, on which you can build further.
Once you create a project, you will find a pom.xml. POM stands for Project Object Model. It is fundamental Unit of Work in Maven.
A simple POM file might look like
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
Note the dependencies part. This is telling the maven which version of the required dependency is needed by application.
If you are using eclipse, converting your existing web project to Maven Project is pretty simple.
Right Click on project-> Configure-> Convert to Maven.
It automatically generates a pom.xml file (Project Object Model). Now you can right click on POM to add dependencies.
When I tried using Maven’s embedded version in Eclipse Kepler, it gave an error.
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
A little googling showed this as a genuine issue with embedded version of Maven in Eclipse. The workaround is to download external maven and link to eclipse.
- Download Maven zip from http://maven.apache.org/download.cgi
- Unzip the file to some location say “D:\Maven”
- In Eclipse go to Windows->Preferences->Maven->Installation; Click add and provide the path in step 2 (D:\Maven)