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3.1）problem：生命周期抽象了构建的 各个steps，定义了它们的次序，但没有提供具体实现。那么谁来实现这些step 呢？3.2）solutions：maven 当然必须要考虑这一点，因此它设计插件机制。每个构建step 都可以绑定一个或者多个插件行为，而且maven 为大多数构建step 编写并绑定了 默认插件；
lifecycle1）clean 生命周期： 的目的是清理项目lifecycle2）default生命周期：的目的是构建项目lifecycle3）site 生命周期： 的目的是建立项目站点；
A1）每个生命周期包含一些阶段：以clean 生命周期为例，包含的 阶段有pre-clean， clean 和 post-clean；A2）三套生命周期本身是相互独立的，用户可以仅仅调用clean生命周期的某个阶段，或者仅仅调用 default 生命周期短某个阶段，而不会对其他生命周期产生任何影响；
stage1）pre-clean：清理前需要完成的工作；stage2）clean：清理上一次构建生成的文件；stage3）post-clean：清理后需要完成的工作；
4.1）intro： maven-dependency-plugin有多个目标，每个目标对应一个功能，上述提到的几个功能分别对应的插件目标为 dependency:analyze, dependency:tree 和 dependency:list；4.2）这是一种通用的写法： 冒号前面是 插件前缀，后面是该插件的目标；（干货——引入了插件前缀）
A1）default 与插件目标的绑定关系是由 项目打包类型所决定的，打包类型是通过 POM 中的 packaging 元素定义的；A2）除了默认的 jar 打包类型外，常见的打包类型还有 war，pom，maven-plugin，ear等；
D:\classical_books\java_set\maven_in_action\mycode\chapter3>mvn clean install [INFO] Scanning for projects... [WARNING] [WARNING] Some problems were encountered while building the effective model for com.maven.chapter3:service:jar:1.0-SNAPSHOT [WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. @ line 22, column 15 [WARNING] [WARNING] It is highly recommended to fix these problems because they threaten the stability of your build. [WARNING] [WARNING] For this reason, future Maven versions might no longer support building such malformed projects. [WARNING] [INFO] [INFO] ------------------------------------------------------------------------ [INFO] Building service says hello maven. 1.0-SNAPSHOT [INFO] ------------------------------------------------------------------------ [INFO] [INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ service --- [INFO] Deleting D:\classical_books\java_set\maven_in_action\mycode\chapter3\target [INFO] [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ service --- [WARNING] Using platform encoding (GBK actually) to copy filtered resources, i.e. build is platform dependent! [INFO] skip non existing resourceDirectory D:\classical_books\java_set\maven_in_action\mycode\chapter3\src\main\resources [INFO] [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ service --- [INFO] Changes detected - recompiling the module! [WARNING] File encoding has not been set, using platform encoding GBK, i.e. build is platform dependent! [INFO] Compiling 1 source file to D:\classical_books\java_set\maven_in_action\mycode\chapter3\target\classes [INFO] [INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ service --- [WARNING] Using platform encoding (GBK actually) to copy filtered resources, i.e. build is platform dependent! [INFO] skip non existing resourceDirectory D:\classical_books\java_set\maven_in_action\mycode\chapter3\src\test\resources [INFO] [INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ service --- [INFO] Changes detected - recompiling the module! [WARNING] File encoding has not been set, using platform encoding GBK, i.e. build is platform dependent! [INFO] Compiling 1 source file to D:\classical_books\java_set\maven_in_action\mycode\chapter3\target\test-classes [INFO] [INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ service --- [INFO] Surefire report directory: D:\classical_books\java_set\maven_in_action\mycode\chapter3\target\surefire-reports ------------------------------------------------------- T E S T S ------------------------------------------------------- Running com.maven.chapter3.service.HelloTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.06 sec Results : Tests run: 1, Failures: 0, Errors: 0, Skipped: 0 [INFO] [INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ service --- [INFO] Building jar: D:\classical_books\java_set\maven_in_action\mycode\chapter3\target\service-1.0-SNAPSHOT.jar [INFO] [INFO] --- maven-shade-plugin:1.2.1:shade (default) @ service --- [INFO] Replacing original artifact with shaded artifact. [INFO] Replacing D:\classical_books\java_set\maven_in_action\mycode\chapter3\target\service-1.0-SNAPSHOT.jar with D:\classical_books\java_set\maven_in _action\mycode\chapter3\target\service-1.0-SNAPSHOT-shaded.jar [INFO] [INFO] --- maven-install-plugin:2.4:install (default-install) @ service --- [INFO] Installing D:\classical_books\java_set\maven_in_action\mycode\chapter3\target\service-1.0-SNAPSHOT.jar to D:\classical_books\java_set\maven_in_ action\local_repo\com\maven\chapter3\service\1.0-SNAPSHOT\service-1.0-SNAPSHOT.jar [INFO] Installing D:\classical_books\java_set\maven_in_action\mycode\chapter3\pom.xml to D:\classical_books\java_set\maven_in_action\local_repo\com\ma ven\chapter3\service\1.0-SNAPSHOT\service-1.0-SNAPSHOT.pom [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 8.305 s [INFO] Finished at: 2016-06-22T18:43:41+08:00 [INFO] Final Memory: 17M/142M [INFO] ------------------------------------------------------------------------
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-source-plugin</artifactId>
<version>2.1.1</version>
<executions>
<execution>
<id>attach-sources</id>
<phase>verify</phase>
<goals>
<goal>jar-no-fork</goal>
</goals>
</execution>
</executions>
</plugin>A1）executions 下每个execution 子元素可以用来配置执行一个任务；A2）该例中配置了一个id 为 attach-sources 的 任务，通过 phrase 配置，将其绑定到 verify 生命周期阶段上，再通过 goal 配置指定要执行的插件 目标，至此，自定义插件配置完成了；（干货——总结了自定义插件配置的steps）
D:\classical_books\java_set\maven_in_action\mycode\chapter3>mvn verify [INFO] Scanning for projects... [WARNING] [WARNING] Some problems were encountered while building the effective model for com.maven.chapter3:service:jar:1.0-SNAPSHOT [WARNING] 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-compiler-plugin is missing. @ line 22, column 15 [WARNING] [WARNING] It is highly recommended to fix these problems because they threaten the stability of your build. [WARNING] [WARNING] For this reason, future Maven versions might no longer support building such malformed projects. [WARNING] [INFO] [INFO] ------------------------------------------------------------------------ [INFO] Building service says hello maven. 1.0-SNAPSHOT [INFO] ------------------------------------------------------------------------ Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-source-plugin/2.1.1/maven-source-plugin-2.1.1.pom Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-source-plugin/2.1.1/maven-source-plugin-2.1.1.pom (5 KB at 2.6 KB/sec) Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-plugins/14/maven-plugins-14.pom Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-plugins/14/maven-plugins-14.pom (13 KB at 32.4 KB/sec) Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-source-plugin/2.1.1/maven-source-plugin-2.1.1.jar Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-source-plugin/2.1.1/maven-source-plugin-2.1.1.jar (24 KB at 59.4 KB/se c) [INFO] [INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ service --- [WARNING] Using platform encoding (GBK actually) to copy filtered resources, i.e. build is platform dependent! [INFO] skip non existing resourceDirectory D:\classical_books\java_set\maven_in_action\mycode\chapter3\src\main\resources [INFO] [INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ service --- [INFO] Nothing to compile - all classes are up to date [INFO] [INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ service --- [WARNING] Using platform encoding (GBK actually) to copy filtered resources, i.e. build is platform dependent! [INFO] skip non existing resourceDirectory D:\classical_books\java_set\maven_in_action\mycode\chapter3\src\test\resources [INFO] [INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ service --- [INFO] Nothing to compile - all classes are up to date [INFO] [INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ service --- [INFO] Surefire report directory: D:\classical_books\java_set\maven_in_action\mycode\chapter3\target\surefire-reports ------------------------------------------------------- T E S T S ------------------------------------------------------- Running com.maven.chapter3.service.HelloTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.056 sec Results : Tests run: 1, Failures: 0, Errors: 0, Skipped: 0 [INFO] [INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ service --- [INFO] Building jar: D:\classical_books\java_set\maven_in_action\mycode\chapter3\target\service-1.0-SNAPSHOT.jar [INFO] [INFO] --- maven-shade-plugin:1.2.1:shade (default) @ service --- [INFO] Replacing original artifact with shaded artifact. [INFO] Replacing D:\classical_books\java_set\maven_in_action\mycode\chapter3\target\service-1.0-SNAPSHOT.jar with D:\classical_books\java_set\maven_in _action\mycode\chapter3\target\service-1.0-SNAPSHOT-shaded.jar [INFO] [INFO] --- maven-source-plugin:2.1.1:jar-no-fork (attach-sources) @ service --- // maven-source-plugin:jar-no-fork 会得以执行. Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/maven-archiver/2.4/maven-archiver-2.4.pom Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/maven-archiver/2.4/maven-archiver-2.4.pom (4 KB at 9.1 KB/sec) Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/shared/maven-shared-components/10/maven-shared-components-10.pom Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/shared/maven-shared-components/10/maven-shared-components-10.pom (9 KB at 19.0 KB/se c) Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/maven-artifact/2.0/maven-artifact-2.0.pom Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/maven-artifact/2.0/maven-artifact-2.0.pom (723 B at 1.8 KB/sec) Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/maven/2.0/maven-2.0.pom Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/maven/2.0/maven-2.0.pom (9 KB at 21.5 KB/sec) Downloading: 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[INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 18.822 s [INFO] Finished at: 2016-06-22T19:00:32+08:00 [INFO] Final Memory: 13M/171M [INFO] ------------------------------------------------------------------------
4.1）problem：当插件目标被绑定到不同的生命周期的时候，其执行顺序会由生命周期阶段的先后顺序决定；当多个目标被绑定到同一阶段时，他们的执行顺序会是怎样？4.2）solutions：当多个插件目标绑定到同一个阶段的时候，这些插件声明的先后顺序决定了目标的执行顺序；
1.1）problem：如何从命令行配置插件？1.2）solutions：用户可以在maven 命令中使用 -D 参数，并伴随一个参数键=参数值的形式，来配置插件目标的参数；参数-D 是java 自带的，其功能是通过命令行设置一个 java 系统属性；（干货——参数-D 是java 自带的，其功能是通过命令行设置一个 java 系统属性）
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin><?xml version="1.0" encoding="UTF-8"?>
<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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.maven.chapter3</groupId>
<artifactId>service</artifactId>
<version>1.0-SNAPSHOT</version>
<name>service says hello maven.</name>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.7</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>1.2.1</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>com.maven.chapter3.service.Hello</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-source-plugin</artifactId>
<version>2.1.1</version>
<executions>
<execution>
<id>attach-sources</id>
<phase>verify</phase>
<goals>
<goal>jar-no-fork</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.3</version>
<executions>
<execution>
<id>ant-validate</id>
<phase>validate</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<tasks>
<echo>i am bound to validate phase.</echo>
</tasks>
</configuration>
</execution>
<execution>
<id>ant-verify</id>
<phase>verify</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<tasks>
<echo>i am bound to verify phase.</echo>
</tasks>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>A1）maven-antrun-plugin:run 与 validate 阶段绑定，从而构成了一个id为 ant-validate 的任务；A2）插件 全局配置中的 configuration 元素位于 plugin 元素下面，而这里的configuration元素则位于 execution 元素下，表示这是 特定任务的配置，而非插件整体的配置；A3）ant-validate任务配置了一个 echo 任务，而id为 ant-verify 任务也配置了一个 echo 任务；
2.1）看个荔枝： maven-compiler-plugin 的目标前缀是 compiler。2.2）在描述插件的时候，还可以省去版本信息，让 maven 自动获取最新版本来进行表述， 如： mvn help:describe-Dplugin=org.apache.maven.plugins:maven-compiler-plugin2.3）进一步简化：可以使用插件目标前缀来替换坐标： mvn help:describe-Dplugin=compiler2.4）想仅仅描述某个插件目标的信息，可以加上 goal 参数：mvn help:describe-Dplugin=compiler-Dgoal=compile2.5）想让 maven-help-plugin 输出更详细的信息，可以加上 detail参数：mvn help:describe-Dplugin=compiler-Ddetail
D:\classical_books\java_set\maven_in_action\mycode\chapter3>mvn -h usage: mvn [options] [<goal(s)>] [<phase(s)>]
mvn help:describe-Dplugin=compiler mvn dependency:tree4）problem+solutions：
4.1）problem：为什么不是 mavnen-dependency-plugin:tree 而是 dependency:tree ？4.2）solutions：可以尝试如下命令：mvn org.apache.maven.plugins:maven-help-plugin:2.1:describe-Dplugin=compiler mvn org.apache.maven.plugins:maven-dependency-plugin:2.1:tree
4.2.1）上面的命令一对比，显然 前面的目录更加简洁，更容易使用；4.2.2）这也是 maven 引入 目标前缀的原因： help 是 maven-help-plugin 的目标前缀， 而 dependency 是 maven-dependency-plugin 的前缀，有了插件前缀，maven 就能够找到对应的 artifactId；不过 除了 artifactId ，maven 还需要得到 groupId 和 version 才能确定到 某个插件；
<settings>
<pluginGroups>
<pluginGroup>com.your.plugins</pluginGroup>
</pluginGroups>
</settings>对以上代码的分析（Analysis）： maven 不仅仅会检查 org/apache/maven/plugins/maven-metadata.xml 和 org/codehaus/mojo/maven-metadata.xml ，还会检查 com/your/plugins/maven-metadata.xml；
A1）上述内容是从 中央仓库的 org.apche.maven.plugins groupId 下插件仓库元数据中截取的一些片段，从这段数据中就能看到 maven-clean-plugin 的前缀为 clean,maven-compile-plugin 的前缀为 compiler， maven-dependency-plugin 的前缀为 dependency；A2）当maven 解析到 dependency:tree 这样的命令后，他首先基于 默认的 groupId 归并所有插件仓库的元数据 org/apache/maven/plugins/maven-metadata.xml； 其次检查归并后的元数据， 找到对应的 artifactId 为 maven-dependency-plugin； 然后结合当前元数据的 groupId org.apache.maven.plugins；最后使用 章节8.3 的方法解析得到 version，从而得到完整的插件坐标；
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原文地址：http://blog.csdn.net/pacosonswjtu/article/details/51736815
