# Maven生命周期 ## 重要概念 **生命周期（Lifecycle）** Maven有三种不同的生命周期（Lifecycle），分别是Clean、Default、Site。每个生命周期又包含不同的阶段（Phase）。 **阶段（Phase）** 当我们在运行一个命令的时候，该命令都会对应某个生命周期的某个阶段，并且该生命周期中的在此阶段之前的命令都会被执行。比如，`mvn clean` 等同于 `mvn pre-clean clean` ，如果我们运行 `mvn post-clean` ，那么 `pre-clean，clean` 都会被运行。这是Maven很重要的一个规则，可以大大简化命令行的输入。 **目标（goal）** 具体某个阶段应该做什么工作，怎么做，Maven有默认的行为，当然也可以通过插件进行定制修改。这就引入了Maven中另一个重要概念：goal。一个phase可以绑定很多个goal，至少为一个，没有goal的phase是没有意义的。goal也是按顺序执行的，一个phase被执行时，绑定到phase里的goal会按绑定的时间被顺序执行，不管phase己经绑定了多少个goal，你自己定义的goal都可以继续绑到phase中。 **mojo** Lifecycle与Phase与goal都是概念上的东西，mojo才是做具体事情的，可以简单理解mojo为goal的实现类，它继承于AbstractMojo，有一个execute方法，goal等的定义都是通过在mojo里定义一些注释的anotation来实现的，maven会在打包时，自动根据这些anotation生成一些xml文件，放在plugin的jar包里。 > lifecycle与phase与goal就是级别的大小问题，引用必须是从高级引用下级（goal绑定到phase，执行时，phase会调用绑定到它那的goal），也不能跨级引用，如lifecycle可以引用任意的phase，不同lifecycle可以同时引用相同的phase，lifecycle不能跨级引用goal。goal会绑定到任意的phase中，也就是说不同的phase可以同时引用相同的goal，所以goal可以在一个lifecycle里被重复执行。 ## **Clean Lifecycle** 在进行真正的构建之前进行一些清理工作，Clean声明周期包含如下三个Phase。 | pre-clean | execute processes needed prior to the actual project cleaning | | ---------- | ------------------------------------------------------------- | | clean | remove all files generated by the previous build | | post-clean | execute processes needed to finalize the project cleaning | 比如，我们在执行mvn clean的时候，其实是让Maven做它的Clean生命周期中的clean阶段应该去做的工作（当然，包含Clean生命周期中clean阶段之前的所有阶段的工作）。 ## **Default Lifecycle** 构建的核心部分，编译，测试，打包，部署等等。 | validate | validate the project is correct and all necessary information is available. | | ----------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | initialize | initialize build state, e.g. set properties or create directories. | | generate-sources | generate any source code for inclusion in compilation. | | process-sources | process the source code, for example to filter any values. | | generate-resources | generate resources for inclusion in the package. | | process-resources | copy and process the resources into the destination directory, ready for packaging. | | compile | compile the source code of the project. | | process-classes | post-process the generated files from compilation, for example to do bytecode enhancement on Java classes. | | generate-test-sources | generate any test source code for inclusion in compilation. | | process-test-sources | process the test source code, for example to filter any values. | | generate-test-resources | create resources for testing. | | process-test-resources | copy and process the resources into the test destination directory. | | test-compile | compile the test source code into the test destination directory | | process-test-classes | post-process the generated files from test compilation, for example to do bytecode enhancement on Java classes. For Maven 2.0.5 and above. | | test | run tests using a suitable unit testing framework. These tests should not require the code be packaged or deployed. | | prepare-package | perform any operations necessary to prepare a package before the actual packaging. This often results in an unpacked, processed version of the package. (Maven 2.1 and above) | | package | take the compiled code and package it in its distributable format, such as a JAR. | | pre-integration-test | perform actions required before integration tests are executed. This may involve things such as setting up the required environment. | | integration-test | process and deploy the package if necessary into an environment where integration tests can be run. | | post-integration-test | perform actions required after integration tests have been executed. This may including cleaning up the environment. | | 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. | 我们最常用的就是`mvn package` 或者`mvn install` 或者`mvn compile`了。 ## **Site Lifecycle** 生成项目报告，站点，发布站点。 | pre-site | execute processes needed prior to the actual project site generation | | ----------- | -------------------------------------------------------------------------------------------- | | site | generate the project's site documentation | | post-site | execute processes needed to finalize the site generation, and to prepare for site deployment | | site-deploy | deploy the generated site documentation to the specified web server | ## 参考 [**Maven生命周期详解**](http://juvenshun.iteye.com/blog/213959) [Maven plugin中的lifecycle、phase、goal、mojo概念及作用的理解](http://gavin-chen.iteye.com/blog/336607) [Introduction to the Build Lifecycle](http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html) [What are Maven goals and phases and what is their difference?](https://stackoverflow.com/questions/16205778/what-are-maven-goals-and-phases-and-what-is-their-difference) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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