Maven 生命周期

1. Maven 構建生命周期

Maven 構建生命周期就是 Maven 將一個整體任務划分為一個個的階段，類似於流程圖，按順序依次執行。也可以指定該任務執行到中間的某個階段結束。
Maven 的內部有三個構建生命周期，分別是 clean, default, site。其中 default 生命周期的核心階段如下所示：

 

default lifecycle

2. 如何使用構建生命周期來完成構建工作

• 可以指定某個生命周期的階段

執行 mvn install 命令，將完成 validate, compile, test, package, verify, install 階段，並將 package 生成的包發布到本地倉庫中。其中某些帶有連字符的階段不能通過 shell 命令單獨指定。例如：(pre-, post-, or process-*)

mvn install

• 可以指定多個不同構建生命周期的階段

執行 mvn clean deploy 命令，首先完成的 clean lifecycle，將以前構建的文件清理，然后再執行 default lifecycle 的 validate, compile, test, package, verify, insstall, deploy 階段，將 package 階段創建的包發布到遠程倉庫中。

mvn clean deploy

3. 階段與插件的關系

如上所述，Maven 將構建過程定義為 default lifecycle，並將 default lifecycle 划分為一個個的階段 phase，這一系列 phase 僅僅是規定執行順序，至於每個階段做什么工作？由誰來做？答案就在 插件（plugins） 中。
Maven 對工程的所有操作實實在在的都是由 插件 來完成的。一個插件可以支持多種功能，稱之為目標（goal），例如：compiler 插件有兩個目標：compile 和 testCompile，分別實現編譯源代碼 和 編譯測試代碼。
如何將插件與 Maven 的構建生命周期綁定在一起呢？通過將插件的目標（goal）與 build lifecycle 中 phase 綁定到一起，這樣，當要執行某個 phase 時，就調用插件來完成綁定的目標。
如下圖所示：從圖中可以看出，每一個階段可以綁定0 個 或 多個目標，每個插件可以提供 1 個或多個目標。

 

 build lifecycle & plugin goal

4. 如何為自己的工程創建構建生命周期

• 設置不同的 packaging 類型

在 pom.xml 文件中，packaging 類型支持 jar, war, ear, pom 等多種類型，不同的 packaging 類型會使得不同的 phase 綁定不同的 plugin goal。下面是 packaging 類型為 jar 時，phase 與 plugin goal 的映射關系。

階段	目標
process-resources	resources:resources
compile	compiler:compile
process-test-resources	resources:testResources
test-compile	compiler:testCompile
test	surefire:test
package	jar:jar
install	install:install
deploy	deploy:deploy

• 配置 plugin

在 pom.xml 文件中， <build> <plugins> 元素下可以添加 <plugin>，通過指定 goal 和 phase 來進行綁定。
例如：將插件 modello-maven-plugin 的 java 目標綁定到 generate-sources 階段。

<plugin>
  <groupId>org.codehaus.modello</groupId>
  <artifactId>modello-maven-plugin</artifactId>
  <version>1.8.1</version>
  <executions>
    <execution>
      <configuration>
        <models>
          <model>src/main/mdo/maven.mdo</model>
        </models>
        <version>4.0.0</version>
      </configuration>
      <phase>generate-sources</phase>
      <goals>
        <goal>java</goal>
      </goals>
    </execution>
  </executions>
</plugin>

5. 我沒有在 pom.xml 指定任何 plugin，但是也能正常構建工程

你可以能會疑問，默認的 pom.xml 文件並沒有配置各種 plugin，但是也能正常構建工程？答案是 Maven 自己默認指定了 plugin。
下面是一個沒有配置任何 plugin 的 pom.xml，執行 mvn install 的輸出日志，從日志中可以看到 一系列的 插件(plugin):版本號:目標(phase)，例如 maven-resources-plugin:2.6:resources (default-resources)，maven-compiler-plugin:3.1:compile (default-compile) ，maven-resources-plugin:2.6:testResources (default-testResources)，maven-compiler-plugin:3.1:testCompile (default-testCompile)，maven-surefire-plugin:2.12.4:test (default-test)，maven-jar-plugin:2.4:jar (default-jar) ，maven-install-plugin:2.4:install (default-install)，

[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building my-app 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ my-app ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ my-app ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/zhangguanghui/git/my-app/target/classes
[INFO]
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ my-app ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/zhangguanghui/git/my-app/src/test/resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ my-app ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/zhangguanghui/git/my-app/target/test-classes
[INFO]
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ my-app ---
[INFO] Surefire report directory: /Users/zhangguanghui/git/my-app/target/surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.mycompany.app.AppTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.004 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO]
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ my-app ---
[INFO] Building jar: /Users/zhangguanghui/git/my-app/target/my-app-1.0-SNAPSHOT.jar
[INFO]
[INFO] --- maven-install-plugin:2.4:install (default-install) @ my-app ---
[INFO] Installing /Users/zhangguanghui/git/my-app/target/my-app-1.0-SNAPSHOT.jar to /Users/zhangguanghui/.m2/repository/com/mycompany/app/my-app/1.0-SNAPSHOT/my-app-1.0-SNAPSHOT.jar
[INFO] Installing /Users/zhangguanghui/git/my-app/pom.xml to /Users/zhangguanghui/.m2/repository/com/mycompany/app/my-app/1.0-SNAPSHOT/my-app-1.0-SNAPSHOT.pom
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.726 s
[INFO] Finished at: 2016-11-20T00:41:11+08:00
[INFO] Final Memory: 15M/310M
[INFO] ------------------------------------------------------------------------

5. 完整的 clean, default, site build lifecycle

• clean lifecycle

phase	function
pre-clean execute	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

• default lifecycle

phase	function
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.

• site lifecycle

phase	function
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

6. 參考文檔

參考

maven 入門指南
maven 生命周期
Maven 默認插件以及功能
maven 依賴管理
maven-shade-plugin 入門指南
maven-assembly-plugin 入門指南
Introduction to the Build Lifecycle

轉自：https://www.jianshu.com/p/fd43b3d0fdb0