maven is a good thing to manage java project...

create a project with maven

before we start to create a project using maven, 
maybe we should set a proxy.....
we can use maven archetype plugin to help us to 
create a maven project , you can see archtype 
as a existing template.

>>mvn archetype:generate
then terminal will prompt you to choose a number(choose a template), 
because there are a lot of choices, so you can use filter to 
filter some like input "quick", then you can see 
maven-archetype-quickstart,maybe its number is 19, 
so you input 19 Enter.

Then it will let you select a version, 
maybe you select the default latest version, just Enter.

Then you need to set some properties:
* groupId: com.sysdev.learn(the unique group id specifies 
where the project is located hierachically in a maven repository,
so you can allow similar projects into similar groups)
* artifactId: learn-helloworld(just think it as a project name)
* version: 1.0
* package: com.sysdev.learn.helloworld

Then it will ask you if confirm these configuration, 
if yes just input Y, then your project is created.

Then you want to see your project in a tree format(if you have installed tree), 
just input: >>tree learn-helloworld.

In a word, creat a project from an archetype involves three steps:
* the selection of the archetype
* the configuration of the archetype
* the effective creation of the project from the selected infomation

ok, at last let us input all the command once:
mvn archetype:create(old,default create quick-start maven project) 
-DgroupId=com.sysdev.learn.helloworld -DartifactId=learn-helloworld
You think it is over?
===
ofcourse not, you will want to develop the project in elipse, so you should import the project to the eclipse,
so cd your-project, use maven eclipse:eslipse goal
>>mvn eclipse:eslipse 
run abvoe command, it just create two files .classpath and .project, which is used for eclipse.
Then just use eslipse IDE to new a project from existing sourcecode.
ofcourse there are some other ways to import an existing maven project to eclipse.
===
After you develop your project for a while, you want to test your project, of course use the test phase of maven build lifecycle.
>>mvn test
you input command above, it will execute the test phase and all the steps of the maven build lifecycle up to the test phase.
===
OK, you have finish you project, so you have to build your project.
>>mvn package
so it will base on pom.xml begin to package......
===
After you package your project, then ou can install it to your local repository for your other project to use.
>>mvn install

===An example to create a web application project with Maven===
>>mvn archetype:generate
>>-DgroupId=com.baijian.web.helloworld
>>-DartifactId=helloworld
>>-DarchetypeArtifactId=maven-archetype-webapp 
>>-DinteractiveMode=false

>>tree ./helloworld

>>mvn eclipse:eclipse -Dwtpversion=2.0
```-Dwtpversion=2.0``` argument is made to let it 
be a web project, then import it to eclipse
IDE, it will be as a web project.