maven快速入门

Creating a Project

On your command line, execute the following Maven goal:
mvn archetype:generate -DgroupId=com.mycompany.app -DartifactId=my-app -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

it may take a while on the first run.

生成如下目录结构

my-app|-- pom.xml`-- src    |-- main    |   `-- java    |       `-- com    |           `-- mycompany    |               `-- app    |                   `-- App.java    `-- test        `-- java            `-- com                `-- mycompany                    `-- app                        `-- AppTest.java

生成的pom.xml文件如下

<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.mycompany.app</groupId>  <artifactId>my-app</artifactId>  <version>1.0-SNAPSHOT</version>  <packaging>jar</packaging>  <name>Maven Quick Start Archetype</name>  <url>http://maven.apache.org</url>  <dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>4.8.2</version>      <scope>test</scope>    </dependency>  </dependencies></project>

Build 工程

mvn package

测试生成的jar包。

java -cp target/my-app-1.0-SNAPSHOT.jar com.mycompany.app.App

Which will print the quintessential:

Hello World!

Running Maven Tools

Maven Phases

Although hardly a comprehensive list, these are the most common default lifecycle phases executed.

• validate: validate the project is correct and all necessary information is available
• compile: 编译资源文件。比如java生成class文件
• test: test the compiled source code using a suitable unit testing framework. These tests should not require the code be packaged or deployed
• package:打包。比如生成jar文件。
• integration-test: process and deploy the package if necessary into an environment where integration tests can be run
• verify: run any checks to verify the package is valid and meets quality criteria
• install: 将打包生成的构造文件到local resposity
• deploy: 将打包生成的构造文件到remote resposity

There are two other Maven lifecycles of note beyond the default list above. They are

• clean: 删除编译生成的target文件。

• site: generates site documentation for this project

1.执行是一个紧连顺序的过程。比如执行install，它之前的阶段都会被执行。

2.mvn可以按顺序的执行所给命令，如下

mvn clean dependency:copy-dependencies package

命令将 clean the project, copy dependencies, and package the project 

使用dependencies

一个依赖的配置片段如下

  <dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>3.8.1</version>      <scope>test</scope>    </dependency>  </dependencies>

1.对于每个external dependency，至少定义四个属性 groupId, artifactId, version, and scope.

2.maven根据依赖的配置来引用仓库中的jar包， 默认从local repository (~/.m2/repository is the default location) 加载。

3.在前面构建的jar包 (my-app-1.0-SNAPSHOT.jar) ， 一旦install后, 另一个工程就可以引用，只需在它的pom.xml:加入下面信息。

<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">  <groupId>com.mycompany.app</groupId>  <artifactId>my-other-app</artifactId>  ...  <dependencies>    ...    <dependency>      <groupId>com.mycompany.app</groupId>      <artifactId>my-app</artifactId>      <version>1.0-SNAPSHOT</version>      <scope>compile</scope>    </dependency>  </dependencies></project>

当依赖不可用时，maven将从remote repository 下载到local repository.缺省的remote repository 为http://repo.maven.apache.org/maven2/. 也可以定义自己remote repository (maybe a central repository for your company) 。

下面将从另一个例子来说明如何使用依赖。当在代码中使用log4j

1.首先要知道log4j的groupId, artifactId, and version ，从网站http://mirrors.ibiblio.org/查询，

相应路径下有个文件 maven-metadata.xml.log4j的maven-metadata.xml 如下:

<metadata>  <groupId>log4j</groupId>  <artifactId>log4j</artifactId>  <version>1.1.3</version>  <versioning>    <versions>      <version>1.1.3</version>      <version>1.2.4</version>      <version>1.2.5</version>      <version>1.2.6</version>      <version>1.2.7</version>      <version>1.2.8</version>      <version>1.2.11</version>      <version>1.2.9</version>      <version>1.2.12</version>    </versions>  </versioning></metadata>

2.在pom.xml 中加入log4j的信息。

<dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>3.8.1</version>      <scope>test</scope>    </dependency>    <dependency>      <groupId>log4j</groupId>      <artifactId>log4j</artifactId>      <version>1.2.12</version>      <scope>compile</scope>    </dependency>  </dependencies>

现在编译时 (mvn compile), maven将下载log4j的jar包。