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] ------------------------------------------------------------------------2) 测试代码位于独立的目录中，默认的测试代码目录是src/test/java,编写测试代码：
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); }} 之后调用Maven执行测试，右键pom.xml --> Run as --> Maven build, 在goals中输入clean test: [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.HelloWorldTestTests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.055 secResults :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] ------------------------------------------------------------------------这样我们就学会如何简单的使用Maven新建项目了，重点要理解POM的基本概念。