1. 什么是POM

Maven项目的核心是pom.xml, POM(Project Object Model)定义了项目的基本信息，用于描述项目如何构建、声明项目依赖等等。

首先我们使用Eclipse新建一个Maven项目，项目名为hello-world，如下图：

在pom.xml中最重要几个重要的元素有groupId、artifactId、version、dependencies等。

groupId:定义了项目属于哪个组，该组一般和项目所在的组织或公司有关。比如你在googlecode上建立一个名为myapp的项目，那么groupId为com.googlecode.myapp。

artifactId: 定义了当前Maven项目中中唯一的ID，比如前面的groupId为com.googlecode.myapp,我们可以为不同的子项目或者模块分配不同的artifactId，如myapp-util, myapp-dao,myapp-web等。

version: 指定了项目当前的版本。SNAPSHOT意为快照，表示项目还在开发中，还不稳定。

dependencies: 该元素下可以包含多个dependency以声明项目的依赖。这里添加了一个依赖--groupId为junit，artifactId为junit，version为4.10.有了这段声明Maven会自动从中央仓库下载junit-4.10.jar。

2. 编写代码

1) Maven项目的主代码位于src/main/java目录中，在上图中我们可以看到。代码编写完毕后，右键pom.xml --> Run as -->Maven build,在Goals输入 clean compile，会得到如下结果：

[INFO] Scanning for projects...  [INFO]                                                                           [INFO] ------------------------------------------------------------------------  [INFO] Building hello-world 0.0.1-SNAPSHOT  [INFO] ------------------------------------------------------------------------  [INFO]   [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ hello-world ---  [INFO] Deleting D:\code\maven\hello-world\target  [INFO]   [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ hello-world ---  [WARNING] Using platform encoding (GBK actually) to copy filtered resources, i.e. build is platform dependent!  [INFO] skip non existing resourceDirectory D:\code\maven\hello-world\src\main\resources  [INFO]   [INFO] --- maven-compiler-plugin:2.5.1:compile (default-compile) @ hello-world ---  [WARNING] File encoding has not been set, using platform encoding GBK, i.e. build is platform dependent!  [INFO] Compiling 1 source file to D:\code\maven\hello-world\target\classes  [INFO] ------------------------------------------------------------------------  [INFO] BUILD SUCCESS  [INFO] ------------------------------------------------------------------------  [INFO] Total time: 2.567s  [INFO] Finished at: Thu Nov 21 22:13:29 CST 2013  [INFO] Final Memory: 9M/101M  [INFO] ------------------------------------------------------------------------

package com.alvinliang.maven;    import static org.junit.Assert.assertEquals;  import org.junit.Test;    public class HelloWorldTest {      @Test   public void testSayHello() {    HelloWorld helloWorld = new HelloWorld();    String result = helloWorld.sayHello();    assertEquals("Hello World", result);   }  }

[INFO] Scanning for projects...  [INFO]                                                                           [INFO] ------------------------------------------------------------------------  [INFO] Building hello-world 0.0.1-SNAPSHOT  [INFO] ------------------------------------------------------------------------  [INFO]   [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ hello-world ---  [INFO] Deleting D:\code\maven\hello-world\target  [INFO]   [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ hello-world ---  [WARNING] Using platform encoding (GBK actually) to copy filtered resources, i.e. build is platform dependent!  [INFO] skip non existing resourceDirectory D:\code\maven\hello-world\src\main\resources  [INFO]   [INFO] --- maven-compiler-plugin:2.5.1:compile (default-compile) @ hello-world ---  [WARNING] File encoding has not been set, using platform encoding GBK, i.e. build is platform dependent!  [INFO] Compiling 1 source file to D:\code\maven\hello-world\target\classes  [INFO]   [INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ hello-world ---  [WARNING] Using platform encoding (GBK actually) to copy filtered resources, i.e. build is platform dependent!  [INFO] skip non existing resourceDirectory D:\code\maven\hello-world\src\test\resources  [INFO]   [INFO] --- maven-compiler-plugin:2.5.1:testCompile (default-testCompile) @ hello-world ---  [WARNING] File encoding has not been set, using platform encoding GBK, i.e. build is platform dependent!  [INFO] Compiling 1 source file to D:\code\maven\hello-world\target\test-classes  [INFO]   [INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ hello-world ---  [INFO] Surefire report directory: D:\code\maven\hello-world\target\surefire-reports    -------------------------------------------------------   T E S T S  -------------------------------------------------------  Running com.alvinliang.maven.HelloWorldTest  Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.055 sec    Results :    Tests run: 1, Failures: 0, Errors: 0, Skipped: 0    [INFO] ------------------------------------------------------------------------  [INFO] BUILD SUCCESS  [INFO] ------------------------------------------------------------------------  [INFO] Total time: 5.214s  [INFO] Finished at: Thu Nov 21 22:35:11 CST 2013  [INFO] Final Memory: 11M/101M  [INFO] ------------------------------------------------------------------------

来自： http://my.oschina.net/liangbo/blog/178171