maven 五分钟 cook

1 分钟：Installation

Maven is a Java tool, so you must have Java installed in order to proceed

First, download Maven and unzip it to your desired installation directory, for example C:\maven in windows, or /usr/local/maven in Linux. After this, add the system variable M2_HOME as well as the $M2_HOME/bin directory to your system path. Type the following in a terminal or command prompt:

mvn --version

It should print out your installed version of Maven, for example:

  Maven version: 2.0.4

Depending upon your network setup, you may require extra configuration. Check out the Guide to Configuring Maven if necessary.

2 分钟：Creating a Project

On your command line, execute the following maven goal:

mvn archetype:create -DgroupId=com.mycompany.app -DartifactId=my-app

If you have just installed Maven, it may take a while on the first run. This is because Maven is downloading the most recent artifacts (plugin jars and other files) into your local repository. You may also need to execute the command a couple of times before it succeeds. This is because the remote server may time out before your downloads are complete. Don't worry, there are ways to fix that.

You will notice that the create goal created a directory with the same name given as the artifactId. Change into that directory.

cd my-app

Under this directory you will notice the following standard project structure .

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

The src/main/java directory contains the project source code, the src/test/java directory contains the test source, and the pom.xml is the project's Project Object Model, or POM.

The POM

The pom.xml file is the core of a project's configuration in Maven. It is a single configuration file that contains the majority of information required to build a project in just the way you want. The POM is huge and can be daunting in its complexity, but it is not necessary to understand all of the intricacies just yet to use it effectively. This project's POM is:

<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>4.0.0modelVersion>
  <groupId>com.mycompany.appgroupId>
  <artifactId>my-appartifactId>
  <packaging>jarpackaging>
  <version>1.0-SNAPSHOTversion>
  <name>Maven Quick Start Archetypename>
  <url>http://maven.apache.orgurl>
  <dependencies>
    <dependency>
      <groupId>junitgroupId>
      <artifactId>junitartifactId>
      <version>3.8.1version>
      <scope>testscope>
    dependency>
  dependencies>
project>

What did I just do?

You executed the Maven goal archetype:create , and passed in various parameters to that goal. The prefix archetype is the plugin that contains the goal. If you are familiar with Ant , you may concieve of this as similar to a task. This goal created a simple project based upon an archetype. Suffice it to say for now that a plugin is a collection of goals with a general common purpose. For example the jboss-maven-plugin, whose purpose is "deal with various jboss items".

3分钟：Build the Project

mvn package

The command line will print out various actions, and end with the following:

 ...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESSFUL
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2 seconds
[INFO] Finished at: Thu Oct 05 21:16:04 CDT 2006
[INFO] Final Memory: 3M/6M
[INFO] ------------------------------------------------------------------------

Unlike the first command executed (archetype:create ) you may notice the second is simply a single word - package . Rather than a goal, this is a phase . A phase is a step in the build lifecycle , which is an ordered sequence of phases. When a phase is given, Maven will execute every phase in the sequence up to and including the one defined. For example, if we execute the compile phase, the phases that actually get executed are:

1. validate
2. generate-sources
3. process-sources
4. generate-resources
5. process-resources
6. compile

You may test the newly compiled and packaged JAR with the following command:

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

Which will print the quintessential:

Hello World!

4分钟：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 : compile the source code of the project 
      
test : test the compiled source code using a suitable unit testing framework. These tests should not require the code be packaged or deployed 
      
package : take the compiled code and package it in its distributable format, such as a JAR. 
      
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 : install the package into the local repository, for use as a dependency in other projects locally 
      
deploy : done in an integration or release environment, copies the final package to the remote repository for sharing with other developers and projects. 
     
     
There are two other Maven lifecycles of note beyond the default list above. They are
     

      
clean : cleans up artifacts created by prior builds 
     
     

      
site : generates site documentation for this project 
     
     
Phases are actually mapped to underlying goals. The specific goals executed per phase is dependant upon the packaging type of the project. For example, package executes jar:jar if the project type is a JAR, and war:war is the project type is - you guessed it - a WAR.
     
An interesting thing to note is that phases and goals may be executed in sequence.
     

      
mvn clean dependency:copy-dependencies package
 
     

     
This command will clean the project, copy dependencies, and package the project (executing all phases up to package , of course).

     
 
      
Generating the Site
 
      
 
       
mvn site
 
      
 
      
This phase generates a site based upon information on the project's pom. You can look at the documentation generated under target/site .
 
     

     
 
      
5分钟：Conclusion
 
      
We hope this quick overview has piqued your interest in the versitility of Maven. Note that this is a very truncated quick-start guide. Now you are ready for more comprehensive details concerning the actions you have just performed. Check out the Maven Getting Started Guide .