恕我直言!!!对于Maven,菜鸟玩dependency,神仙玩plugin

打包是一项神圣、而庄严的工作。package意味着我们离生产已经非常近了。它会把我们之前的大量工作浓缩成为一个、或者多个文件。接下来,运维的同学就可以拿着这些个打包文件在生产上纵横四海了。

这么一项庄严、神圣的工作,却没有受到多数人的关注,大家习惯去网上随意copy一段pom的xml代码,往自己项目里面一扔,然后就开始执行package打包了。大多数只知道,Maven帮助我管理了JAR包的依赖,可以自动下载,很方便。确实,因为它太方便了,很多时候,我们几乎是没有感知它的存在。想起来某个功能的时候,直接去使用就可以了。

而构建的工作其实并不简单!例如:

  • 打包后的程序,与生产环境JAR包冲突
  • 依赖中有多个版本的依赖,如何选择、排除依赖
  • 编译scala,某些JAR包的调用存在兼容问题
  • 如何根据不同的环境来加载不同的配置,例如:本地环境、集群环境。
  • 编译开源项目报错,根本无从下手解决。
  • ...

其实,稍微离生产环境近一些,我们会发现很多的问题都暴露了出来。碰到这些问题的时候,当然可以第一时间百度。但为了能够更精准的定位问题、减少打包时候给别人挖坑,我们还是很有必要来了解一些关于Maven的细节。

目录

目录

菜鸟玩dependency,神仙玩plugin

我们使用Maven的时候,95%的时候关注是dependency,而很少有人真正会花时间去研究Maven的plugin。但小猴要告诉大家,其实Maven工作的核心是plugin,而不是dependency。好吧!再直接一点,菜鸟玩dependency,神仙玩plugin。是不是拼命想要反驳我,大家看看官网Plugin在Maven文档的位置,这意味着什么?

灵魂拷问:大家留意过吗?是不是只去官网上下载Maven,然后随便百度一个教程就开始用Maven了?

分析Hadoop Example模块打包

学习的一种最好方式就是借鉴,借鉴优秀的开源项目。看看别人是怎么做的。所以,接下来,我们就来看看Hadoop是如何打包的。为了方便给大家演示,小猴特意用Maven给大家演示一遍编译、打包。这样效果会明显些。

操作步骤:

  1. 在github上找到Apahce/hadoop项目(https://github.com/apache/hadoop)
  2. 找到hadoop-mapreduce-project / hadoop-mapreduce-examples模块。
  3. 打开pom.xml文件。
<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
                      https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-project</artifactId>
    <version>3.4.0-SNAPSHOT</version>
    <relativePath>../../hadoop-project</relativePath>
  </parent>
  <artifactId>hadoop-mapreduce-examples</artifactId>
  <version>3.4.0-SNAPSHOT</version>
  <description>Apache Hadoop MapReduce Examples</description>
  <name>Apache Hadoop MapReduce Examples</name>
  <packaging>jar</packaging>

  <properties>
    <mr.examples.basedir>${basedir}</mr.examples.basedir>
  </properties>

  <dependencies>
    <dependency>
      <groupId>commons-cli</groupId>
      <artifactId>commons-cli</artifactId>
    </dependency>
    <dependency>
      <groupId>commons-logging</groupId>
      <artifactId>commons-logging</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-mapreduce-client-jobclient</artifactId>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-mapreduce-client-jobclient</artifactId>
      <scope>test</scope>
      <type>test-jar</type>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-common</artifactId>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-common</artifactId>
      <scope>test</scope>
      <type>test-jar</type>
    </dependency>
    <dependency>
      <groupId>org.apache.hadoop</groupId>
      <artifactId>hadoop-hdfs-client</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-hdfs</artifactId>
       <scope>test</scope>
       <type>test-jar</type>
     </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-yarn-server-tests</artifactId>
       <scope>test</scope>
       <type>test-jar</type>
     </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-mapreduce-client-app</artifactId>
       <scope>provided</scope>
     </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-mapreduce-client-app</artifactId>
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>
    <dependency>
      <groupId>com.sun.jersey.jersey-test-framework</groupId>
      <artifactId>jersey-test-framework-grizzly2</artifactId>
      <scope>test</scope>
    </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>
       <artifactId>hadoop-mapreduce-client-hs</artifactId>
       <scope>test</scope>
     </dependency>
     <dependency>
       <groupId>org.hsqldb</groupId>
       <artifactId>hsqldb</artifactId>
       <scope>provided</scope>
     </dependency>
     <dependency>
      <groupId>org.apache.hadoop.thirdparty</groupId>
      <artifactId>hadoop-shaded-guava</artifactId>
      <scope>provided</scope>
     </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
    </dependency>
    <dependency>
      <groupId>org.assertj</groupId>
      <artifactId>assertj-core</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>
  
  <build>
   <plugins>
    <plugin>
    <groupId>org.apache.maven.plugins</groupId>
     <artifactId>maven-jar-plugin</artifactId>
      <configuration>
       <archive>
         <manifest>
           <mainClass>org.apache.hadoop.examples.ExampleDriver</mainClass>
         </manifest>
       </archive>
     </configuration>
    </plugin>

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>findbugs-maven-plugin</artifactId>
         <configuration>
          <findbugsXmlOutput>true</findbugsXmlOutput>
          <xmlOutput>true</xmlOutput>
          <excludeFilterFile>${mr.examples.basedir}/dev-support/findbugs-exclude.xml</excludeFilterFile>
          <effort>Max</effort>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.rat</groupId>
        <artifactId>apache-rat-plugin</artifactId>
        <configuration>
          <excludes>
            <exclude>src/main/java/org/apache/hadoop/examples/dancing/puzzle1.dta</exclude>
          </excludes>
        </configuration>
      </plugin>
   </plugins>
   </build>
</project>

通过浏览hadoop example的xml文件,我们发现了以下几点:

  1. 所有的依赖都在父工程hadoop-project的pom.xml中定义好了。在hadoop example项目中,没有出现任何一个版本号。

  2. Hadoop使用了三个插件,一个是maven-jar-plugin、一个是findbugs-maven-plugin、还有一个是apache-rat-plugin。

我们进入到example模块中pom.xml所在的目录中,直接执行mvn package试试看。

[root@compile hadoop-mapreduce-examples]# mvn package
[INFO] Scanning for projects...
[INFO] 
[INFO] ------------< org.apache.hadoop:hadoop-mapreduce-examples >-------------
[INFO] Building Apache Hadoop MapReduce Examples 3.2.1
[INFO] --------------------------------[ jar ]---------------------------------
Downloading from apache.snapshots.https: https://repository.apache.org/content/repositories/snapshots/org/apache/hadoop/hadoop-mapreduce-client-app/3.2.1/hadoop-mapreduce-client-app-3.2.1-tests.jar
.....

[INFO] 
[INFO] --- maven-antrun-plugin:1.7:run (create-testdirs) @ hadoop-mapreduce-examples ---
[INFO] Executing tasks

main:
[INFO] Executed tasks
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ hadoop-mapreduce-examples ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /opt/hadoop-3.2.1-src/hadoop-mapreduce-project/hadoop-mapreduce-examples/src/main/resources
[INFO] 

[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ hadoop-mapreduce-examples ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 

[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ hadoop-mapreduce-examples ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /opt/hadoop-3.2.1-src/hadoop-mapreduce-project/hadoop-mapreduce-examples/src/test/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ hadoop-mapreduce-examples ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- maven-surefire-plugin:3.0.0-M1:test (default-test) @ hadoop-mapreduce-examples ---
Downloading from central: http://maven.aliyun.com/nexus/content/groups/public/org/apache/maven/surefire/surefire-junit4/3.0.0-M1/surefire-junit4-3.0.0-M1.jar

..........

[INFO] 
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running org.apache.hadoop.examples.TestBaileyBorweinPlouffe
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.536 s - in org.apache.hadoop.examples.TestBaileyBorweinPlouffe

..........

[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 11, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] 
[INFO] --- maven-jar-plugin:2.5:jar (default-jar) @ hadoop-mapreduce-examples ---
[INFO] 
[INFO] --- maven-site-plugin:3.6:attach-descriptor (attach-descriptor) @ hadoop-mapreduce-examples ---
[INFO] Skipping because packaging 'jar' is not pom.
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  01:11 min
[INFO] Finished at: 2021-02-06T10:49:18+08:00
[INFO] ------------------------------------------------------------------------

很快就编译成功了,我们来看看Maven做了什么:

1、执行maven-antrun-plugin插件的run create-testdirs任务。奇怪的是,Example模块中并没有引入该插件。一会来看看该插件在何处配置的。

[INFO] --- maven-antrun-plugin:1.7:run (create-testdirs) @ hadoop-mapreduce-examples ---
[INFO] Executing tasks

2、执行maven-resources-plugin插件的resources任务,这个插件应该是拷贝resource目录到target的。

[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ hadoop-mapreduce-examples ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /opt/hadoop-3.2.1-src/hadoop-mapreduce-project/hadoop-mapreduce-examples/src/main/resources

3、执行maven-compiler-plugin插件的compile任务,注意:现在才开始编译代码。因为发现我们之前已经编译过了,所以此处并没有重新编译class。

[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ hadoop-mapreduce-examples ---
[INFO] Compiling 47 source files to /opt/hadoop-3.2.1-src/hadoop-mapreduce-project/hadoop-mapreduce-examples/target/classes

4、执行maven-resources-plugin插件的testResources任务,顾名思义,就是将单元测试相关的resource目录拷贝到target。

[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ hadoop-mapreduce-examples ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /opt/hadoop-3.2.1-src/hadoop-mapreduce-project/hadoop-mapreduce-examples/src/test/resources

5、执行maven-compiler-plugin插件的testCompile任务,同样,将单元测试的文件编译一遍。

[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ hadoop-mapreduce-examples ---
[INFO] Compiling 7 source files to /opt/hadoop-3.2.1-src/hadoop-mapreduce-project/hadoop-mapreduce-examples/target/test-classes

6、执行maven-surefire-plugin插件的test任务,开始执行单元测试。确保编译的代码没有问题。

INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running org.apache.hadoop.examples.TestBaileyBorweinPlouffe
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.436 s - in org.apache.hadoop.examples.TestBaileyBorweinPlouffe
[INFO] Running org.apache.hadoop.examples.TestWordStats
[INFO] Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 4.332 s - in org.apache.hadoop.examples.TestWordStats
[INFO] Running org.apache.hadoop.examples.pi.math.TestLongLong
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.163 s - in org.apache.hadoop.examples.pi.math.TestLongLong
[INFO] Running org.apache.hadoop.examples.pi.math.TestModular
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.164 s - in org.apache.hadoop.examples.pi.math.TestModular
[INFO] Running org.apache.hadoop.examples.pi.math.TestSummation
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.091 s - in org.apache.hadoop.examples.pi.math.TestSummation
[INFO] Running org.apache.hadoop.examples.terasort.TestTeraSort
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 4.449 s - in org.apache.hadoop.examples.terasort.TestTeraSort

7、执行maven-jar-plugin插件的jar任务,这个任务是打包成jar文件。

[INFO] --- maven-jar-plugin:2.5:jar (default-jar) @ hadoop-mapreduce-examples ---
[INFO] Building jar: /opt/hadoop-3.2.1-src/hadoop-mapreduce-project/hadoop-mapreduce-examples/target/hadoop-mapreduce-examples-3.2.1.jar

8、执行maven-site-plugin的attach-descriptor任务。该任务只有项目是pom打包时候才可用,将site.xml(site描述符)添加到部署的文件列表中。

[INFO] --- maven-site-plugin:3.6:attach-descriptor (attach-descriptor) @ hadoop-mapreduce-examples ---
[INFO] Skipping because packaging 'jar' is not pom.

由此,我们可以发现,当我们执行一个package、compile、或者clean命令时,其实背后都是执行Maven的一个插件。只不过有的插件是Maven自带的,直接可以使用,当我们需要自定义插件的行为时,就需要显示在pom.xml中显式配置插件了。

Maven中有大量的、丰富的插件供开发人员使用。

地址:https://maven.apache.org/plugins/

我们可以点击任意一个plugin,查看其具体的内容。

maven-antrun-plugin插件

我们发现在example模块的父模块hadoop-project中有一个pom.xml。

 <plugin>
     <groupId>org.apache.maven.plugins</groupId>
     <artifactId>maven-antrun-plugin</artifactId>
     <executions>
         <execution>
             <id>create-testdirs</id>
             <phase>validate</phase>
             <goals>
                 <goal>run</goal>
             </goals>
             <configuration>
                 <target>
                     <mkdir dir="${test.build.dir}"/>
                     <mkdir dir="${test.build.data}"/>
                 </target>
             </configuration>
         </execution>
     </executions>
</plugin>

我们看到这里面有配置一些插件,其中就个maven-antrun-plugin。该插件会执行run#create-testdirs任务,并且在validate阶段执行。我们看到,该插件执行了两次mkdir。

maven-jar-plugin插件

插件配置如下:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-jar-plugin</artifactId>
    <configuration>
        <archive>
            <manifest>
                <mainClass>org.apache.hadoop.examples.ExampleDriver</mainClass>
            </manifest>
        </archive>
    </configuration>
</plugin>

前面,我们看到了是在执行package阶段时自动执行的。并且指定了运行的主类是ExampleDriver。通过查看打包后的JAR文件,我们可以发现,JAR插件只会将项目中的class文件打包到JAR文件中,并不会打包其他的依赖。

并且,在JAR包的META-INF(元数据中),可以看到MAINFEST.MF文件,已经生成了运行主类:

这个插件的相关说明,可以参看官网:https://maven.apache.org/plugins/maven-jar-plugin/

JAR包中的META-INF目录

在每个jar包中有一个META-INF目录,顾名思义。它肯定是包含了JAR文件的元数据相关。Java基于META-INF目录中的文件来配置Java应用程序、类加载器以及其他服务。它包含以下内容:

MANIFEST.MF

用于定义扩展名以及打包相关的清单。

Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Built-By: China
Created-By: Apache Maven 3.5.0
Build-Jdk: 1.8.0_241
Main-Class: cn.monkey.StreamingJob

该文件中显示了文件的版本、由哪个用户构建的、由哪个应用创建的、构建的JDK版本、以及非常重要的Main-Class。

INDEX.LIST

该文件由JAR工具的-i选项生成,包括了应用程序或者扩展中定义的包的位置。用于类加载器加速类加载过程。

xxx.SF

JAR包的签名文件

xxx.DSA

与SF文件关联的签名块文件。该文件存储了签名文件对应的数字签名。

Maven插件

Maven构建生命周期

Maven是一个项目管理工具,它把项目的构建主要分为了以下阶段:

  • validate:验证项目是否正确,所有必要的信息是否均已经提供
  • compile:编译项目的源代码。
  • test:运行单元测试。
  • package:打包已编译的代码。
  • verify:对集成测试结果进行检查,确保符合质量标准。
  • install:将软件包安装到本地仓库。
  • deploy:将最终的软件包复制到远程仓库,方便和其他开发人员共享。

也就是说,只要是一个Maven项目,从源代码到一个可运行的程序,需要经历着一系列的构建阶段。而每个阶段的背后,是Maven提供了一个构建过程的核心执行引擎,这个核心的项目构建执行引擎是由大量的插件来执行具体的任务。

重新定义Maven

让我们从技术角度,重新定义Maven——一个包含了很多插件的框架。真正执行各种Maven操作的其实都是插件。例如:

  • 构建JAR包
  • 构建WAR包
  • 编译代码
  • 执行单元测试
  • 创建项目文档

等等。只要是能够想到需要在项目上执行的所有操作,其背后都是插件实现的。

插件是Maven的核心功能,一旦定义好了插件,就可以在多个项目中重用。想想,我们是不是在每个pom.xml配置打包插件、编译插件等等。找到pom.xml的位置,然后执行 package、comile、clean等操作即可。当我们执行:

mvn compile

的时候,Maven得知道,哦!当前要执行编译了。由此可以知道,Maven的插件是由mvn的参数来驱动的。这些参数定义了插件的目标(或者Mojo)。

Mojo

Maven中最简单的插件是Clean Plugin。它只是负责删除Maven项目的target目录。但运行mvn clean时,Maven将执行Clean插件中定义的clean目标(Goal),并删除目标目录。Clean插件还定义了可用于自定义插件行为的参数,长概述为outputDirectory,默认为${project.build.directory}。

Mojo实际上是Maven插件中的一个目标(Goal),一个插件可以包含许多的Goal。我们可以用带注解的Java类或者BeanShell脚本来定义Mojo。它指定了Goal相关的元数据:Goal名称、以及Goal所运行的生命周期、以及参数。

查看clean插件源码

通过Maven官网的plugins链接,我们可以找到clean插件在github的地址。

看到src目录和pom.xml,我们就可以知道,原来Maven的plugin也是一个Maven标准项目。先来看看pom.xml里面有什么。为了方便观察,我删除了一些代码。

<project>
  <modelVersion>4.0.0</modelVersion>

  <parent>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-plugins</artifactId>
    <version>34</version>
    <relativePath/>
  </parent>

  <properties>
    <mavenVersion>3.1.1</mavenVersion>
    <javaVersion>7</javaVersion>
    <surefire.version>2.22.2</surefire.version>
    <mavenPluginToolsVersion>3.6.0</mavenPluginToolsVersion>
    <project.build.outputTimestamp>2020-04-07T21:04:00Z</project.build.outputTimestamp>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-plugin-api</artifactId>
      <version>${mavenVersion}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.maven.shared</groupId>
      <artifactId>maven-shared-utils</artifactId>
      <version>3.2.1</version>
    </dependency>

    <!-- dependencies to annotations -->
    <dependency>
      <groupId>org.apache.maven.plugin-tools</groupId>
      <artifactId>maven-plugin-annotations</artifactId>
      <scope>provided</scope>
    </dependency>

  <build>
    <pluginManagement>
      <plugins>
        <!-- remove with next parent upgrade -->
        <plugin>
          <artifactId>maven-project-info-reports-plugin</artifactId>
          <version>3.1.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-enforcer-plugin</artifactId>
          <version>3.0.0-M3</version>
        </plugin>
        <plugin>
          <artifactId>maven-javadoc-plugin</artifactId>
          <version>3.2.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-site-plugin</artifactId>
          <version>3.9.1</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
      
  <profiles>
    <profile>
      <id>run-its</id>
      <build>
        <pluginManagement>
          <plugins>
            <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-invoker-plugin</artifactId>
              <configuration>
                <debug>true</debug>
                <addTestClassPath>true</addTestClassPath>
                <projectsDirectory>src/it</projectsDirectory>
                <cloneProjectsTo>${project.build.directory}/it</cloneProjectsTo>
                <pomIncludes>
                  <pomInclude>*/pom.xml</pomInclude>
                </pomIncludes>
                <preBuildHookScript>setup</preBuildHookScript>
                <postBuildHookScript>verify</postBuildHookScript>
                <localRepositoryPath>${project.build.directory}/local-repo</localRepositoryPath>
                <settingsFile>src/it/settings.xml</settingsFile>
                <goals>
                  <goal>clean</goal>
                </goals>
              </configuration>
            </plugin>
          </plugins>
        </pluginManagement>
      </build>
    </profile>
  </profiles>
</project>

我们看到,pom.xml中引入了一些必要的依赖、以及定义了一些其他插件的版本、在profile中,还定义了maven-invoker-plugin的配置。里面配置了

Invoker插件:用于运行一组Maven项目,该插件可以确定每个项目执行是否成功,并且可以选择验证从给定项目执行生成的输出。比较适合用于集成测试。

我们看到了源码中有一个CleanMojo的源文件,代码中使用了注解来定义插件的Goal和参数。

我们看到execute中就是执行clean目标,里面调用了Cleaner来清理文件。再查看下install插件的Mojo

install默认绑定的是INSTALL阶段。

看完上面的源码,我们知道:以后使用插件,可以看看它的Mojo文件就知道它对应的目标是什么、参数是什么。我们还可以通过插件的源码来进行错误排查。

分析Flink Archetype中的pom.xml

scala版本的pom.xml依赖要比Java版本要复杂,因为Maven默认就是用于构建Java的。而针对scala的构建,需要进行额外配置Maven支持。

mvn archetype:generate \
-DarchetypeGroupId=org.apache.flink \
-DarchetypeArtifactId=flink-quickstart-scala \
-DarchetypeVersion=1.12.1

Flink自动生成的代码如下:

<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>cn.monkey</groupId>
	<artifactId>flink_scala_demo_1.12.1</artifactId>
	<version>1.0-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>Flink Quickstart Job</name>

	<repositories>
		<repository>
			<id>apache.snapshots</id>
			<name>Apache Development Snapshot Repository</name>
			<url>https://repository.apache.org/content/repositories/snapshots/</url>
			<releases>
				<enabled>false</enabled>
			</releases>
			<snapshots>
				<enabled>true</enabled>
			</snapshots>
		</repository>
	</repositories>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<flink.version>1.12.1</flink.version>
		<scala.binary.version>2.11</scala.binary.version>
		<scala.version>2.11.12</scala.version>
		<log4j.version>2.12.1</log4j.version>
	</properties>

	<dependencies>
		<!-- Apache Flink dependencies -->
		<!-- These dependencies are provided, because they should not be packaged into the JAR file. -->
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-scala_${scala.binary.version}</artifactId>
			<version>${flink.version}</version>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-streaming-scala_${scala.binary.version}</artifactId>
			<version>${flink.version}</version>
			<scope>provided</scope>
		</dependency>
		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-clients_${scala.binary.version}</artifactId>
			<version>${flink.version}</version>
			<scope>provided</scope>
		</dependency>

		<!-- Scala Library, provided by Flink as well. -->
		<dependency>
			<groupId>org.scala-lang</groupId>
			<artifactId>scala-library</artifactId>
			<version>${scala.version}</version>
			<scope>provided</scope>
		</dependency>

		<!-- Add connector dependencies here. They must be in the default scope (compile). -->

		<!-- Example:

		<dependency>
			<groupId>org.apache.flink</groupId>
			<artifactId>flink-connector-kafka_${scala.binary.version}</artifactId>
			<version>${flink.version}</version>
		</dependency>
		-->

		<!-- Add logging framework, to produce console output when running in the IDE. -->
		<!-- These dependencies are excluded from the application JAR by default. -->
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-slf4j-impl</artifactId>
			<version>${log4j.version}</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-api</artifactId>
			<version>${log4j.version}</version>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-core</artifactId>
			<version>${log4j.version}</version>
			<scope>runtime</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<!-- We use the maven-shade plugin to create a fat jar that contains all necessary dependencies. -->
			<!-- Change the value of <mainClass>...</mainClass> if your program entry point changes. -->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-shade-plugin</artifactId>
				<version>3.1.1</version>
				<executions>
					<!-- Run shade goal on package phase -->
					<execution>
						<phase>package</phase>
						<goals>
							<goal>shade</goal>
						</goals>
						<configuration>
							<artifactSet>
								<excludes>
									<exclude>org.apache.flink:force-shading</exclude>
									<exclude>com.google.code.findbugs:jsr305</exclude>
									<exclude>org.slf4j:*</exclude>
									<exclude>org.apache.logging.log4j:*</exclude>
								</excludes>
							</artifactSet>
							<filters>
								<filter>
									<!-- Do not copy the signatures in the META-INF folder.
									Otherwise, this might cause SecurityExceptions when using the JAR. -->
									<artifact>*:*</artifact>
									<excludes>
										<exclude>META-INF/*.SF</exclude>
										<exclude>META-INF/*.DSA</exclude>
										<exclude>META-INF/*.RSA</exclude>
									</excludes>
								</filter>
							</filters>
							<transformers>
								<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
									<mainClass>cn.monkey.StreamingJob</mainClass>
								</transformer>
							</transformers>
						</configuration>
					</execution>
				</executions>
			</plugin>

			<!-- Java Compiler -->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.1</version>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
				</configuration>
			</plugin>

			<!-- Scala Compiler -->
			<plugin>
				<groupId>net.alchim31.maven</groupId>
				<artifactId>scala-maven-plugin</artifactId>
				<version>3.2.2</version>
				<executions>
					<execution>
						<goals>
							<goal>compile</goal>
							<goal>testCompile</goal>
						</goals>
					</execution>
				</executions>
				<configuration>
					<args>
						<arg>-nobootcp</arg>
					</args>
				</configuration>
			</plugin>

			<!-- Eclipse Scala Integration -->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-eclipse-plugin</artifactId>
				<version>2.8</version>
				<configuration>
					<downloadSources>true</downloadSources>
					<projectnatures>
						<projectnature>org.scala-ide.sdt.core.scalanature</projectnature>
						<projectnature>org.eclipse.jdt.core.javanature</projectnature>
					</projectnatures>
					<buildcommands>
						<buildcommand>org.scala-ide.sdt.core.scalabuilder</buildcommand>
					</buildcommands>
					<classpathContainers>
						<classpathContainer>org.scala-ide.sdt.launching.SCALA_CONTAINER</classpathContainer>
						<classpathContainer>org.eclipse.jdt.launching.JRE_CONTAINER</classpathContainer>
					</classpathContainers>
					<excludes>
						<exclude>org.scala-lang:scala-library</exclude>
						<exclude>org.scala-lang:scala-compiler</exclude>
					</excludes>
					<sourceIncludes>
						<sourceInclude>**/*.scala</sourceInclude>
						<sourceInclude>**/*.java</sourceInclude>
					</sourceIncludes>
				</configuration>
			</plugin>
			<plugin>
				<groupId>org.codehaus.mojo</groupId>
				<artifactId>build-helper-maven-plugin</artifactId>
				<version>1.7</version>
				<executions>
					<!-- Add src/main/scala to eclipse build path -->
					<execution>
						<id>add-source</id>
						<phase>generate-sources</phase>
						<goals>
							<goal>add-source</goal>
						</goals>
						<configuration>
							<sources>
								<source>src/main/scala</source>
							</sources>
						</configuration>
					</execution>
					<!-- Add src/test/scala to eclipse build path -->
					<execution>
						<id>add-test-source</id>
						<phase>generate-test-sources</phase>
						<goals>
							<goal>add-test-source</goal>
						</goals>
						<configuration>
							<sources>
								<source>src/test/scala</source>
							</sources>
						</configuration>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>
</project>

这是一个标准Flink Maven脚手架,Flink清晰地告诉了我们,哪些依赖是需要设置为provided、哪些是runtime,如果需要使用connector,需要自己额外引入对应不同存储库的connector。我们重点来分析插件:

  • maven-shade-plugin:可以看到,Flink是使用shade插件进行fat jar打包的。可以通过mainClass参数配置jar包的入口。
  • maven-compiler-plugin:配置Java编译器。Flink默认使用1.8进行编译。
  • scala-maven-plugin:配置Scala编译器。
  • maven-eclipse-plugin:该插件定义了编译scala和java文件

我们重点来看shade插件。

注意:

如果多个插件配置的生命周期阶段为package,那么会按照pom.xml的顺序依次执行。

Shade插件

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>3.1.1</version>
    <executions>
        <!-- Run shade goal on package phase -->
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
            <configuration>
                <artifactSet>
                    <excludes>
                        <exclude>org.apache.flink:force-shading</exclude>
                        <exclude>com.google.code.findbugs:jsr305</exclude>
                        <exclude>org.slf4j:*</exclude>
                        <exclude>org.apache.logging.log4j:*</exclude>
                    </excludes>
                </artifactSet>
                <filters>
                    <filter>
                        <!-- Do not copy the signatures in the META-INF folder.
         Otherwise, this might cause SecurityExceptions when using the JAR. -->
                        <artifact>*:*</artifact>
                        <excludes>
                            <exclude>META-INF/*.SF</exclude>
                            <exclude>META-INF/*.DSA</exclude>
                            <exclude>META-INF/*.RSA</exclude>
                        </excludes>
                    </filter>
                </filters>
                <transformers>
                    <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                        <mainClass>cn.monkey.StreamingJob</mainClass>
                    </transformer>
                </transformers>
            </configuration>
        </execution>
    </executions>
</plugin>

Shade插件可以将打包所有的artifact到一个uber-jar(uber-jar表示在一个JAR文件中包含自身、以及所有的依赖)。Shade插件只有一个goal:shade:shade。

Mojo源码URL:https://github.com/apache/maven-shade-plugin/blob/master/src/main/java/org/apache/maven/plugins/shade/mojo/ShadeMojo.java

可以看到,该插件的生命周期配置在package,也就是执行package时,会自动运行。

在configuration中配置了要排除哪些artifacts。filter中配置了排除所有JAR包中的签名文件。我们可以在artifactSet、filter中来解决包冲突问题。

Assembly插件

简介

很多时候我们需要把项目打包成一个tar.gz包,就像Apache的一些组件一样。通过使用Assembly插件可以将程序、文档、配置文件等等打包成一个“assemblies”。使用一个assembly descriptor可以描述整个过程。使用该插件,可以把应用打包成以下类型:

zip
tar
tar.gz (or tgz)
tar.bz2 (or tbz2)
tar.snappy
tar.xz (or txz)
jar
dir
war

而如果要打包成user-jar,assembly插件提供了一些基本的支持。官方建议还是使用shade插件。Assembly插件的使用步骤如下:

  1. 选择或编写一个assembly descriptor
  2. 在pom.xml文件中配置assembly插件
  3. 运行mvn assembly:single

Assembly介绍

Assembly(程序集)指的是一组文件、目录以及相关的依赖,为了方便软件的安装、部署、以及分发,我们可以把Assembly组织成一个zip包、或者tar.gz这种类型的包。例如:一个Maven项目中包含了控制台应用和FX桌面客户端应用。可以定义两个Assembly,将应用和不同的脚本、依赖绑定到一起。

针对Assembly,需要有一个Assembly Descriptor(程序集描述符),通过assembly descripor文件可以描述将哪些文件复制到bin目录,并且可以修改目录中文件的权限。

Goal

每一个Maven插件都会有一个Goal,Assembly插件也有一个Goal,那就是single,表示创建所有的Assembly。

分析Hadoop项目的Assembly插件

Maven插件配置

我们来看一下Hadoop中如何使用该插件的。

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-assembly-plugin</artifactId>
    <inherited>false</inherited>
    <executions>
        <execution>
            <id>src-dist</id>
            <phase>package</phase>
            <goals>
                <goal>single</goal>
            </goals>
            <configuration>
                <appendAssemblyId>false</appendAssemblyId>
                <attach>false</attach>
                <finalName>hadoop-${project.version}-src</finalName>
                <outputDirectory>hadoop-dist/target</outputDirectory>
                <!-- Not using descriptorRef and hadoop-assembly dependency -->
                <!-- to avoid making hadoop-main to depend on a module      -->
                <descriptors>
                    <descriptor>hadoop-assemblies/src/main/resources/assemblies/hadoop-src.xml</descriptor>
                </descriptors>
            </configuration>
        </execution>
    </executions>
</plugin>

解释下每个XML节点的意义:

配置项 说明
appendAssemblyId 设置为false表示从最终的输出程序集中排除src-dist名字
attach 控制Assembly插件是否将生成的assembly附加到项目中
finalName Assembly发行版最终的文件名
outputDirectory Assembly文件的最终输出目录
descriptors 默认会从bin、jar-with-dependencies、src、project中加载内置描述符。

内置的descriptors可以从assembly.jar中加载。

可以参考https://maven.apache.org/plugins/maven-assembly-plugin/descriptor-refs.html看到所有内置的descriptor中说明。这里Hadoop配置的是自己的descriptor。

大家可以参考插件的AbstractAssemblyMojo.java中的定义。

hadoop-src.xml Assembly配置

<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 http://maven.apache.org/xsd/assembly-1.1.3.xsd">
  <id>hadoop-src</id>
  <formats>
    <format>tar.gz</format>
  </formats>
  <includeBaseDirectory>true</includeBaseDirectory>
  <fileSets>
    <fileSet>
      <directory>.</directory>
      <includes>
        <include>LICENCE.txt</include>
        <include>README.txt</include>
        <include>NOTICE.txt</include>
      </includes>
    </fileSet>
    <fileSet>
      <directory>./licenses</directory>
      <includes>
        <include>*</include>
      </includes>
    </fileSet>
    <fileSet>
      <directory>.</directory>
      <useDefaultExcludes>true</useDefaultExcludes>
      <excludes>
        <exclude>.git/**</exclude>
        <exclude>**/.gitignore</exclude>
        <exclude>**/.svn</exclude>
        <exclude>**/*.iws</exclude>
        <exclude>**/*.ipr</exclude>
        <exclude>**/*.iml</exclude>
        <exclude>**/.classpath</exclude>
        <exclude>**/.project</exclude>
        <exclude>**/.settings</exclude>
        <exclude>**/target/**</exclude>
        <!-- until the code that does this is fixed -->
        <exclude>**/*.log</exclude>
        <exclude>**/build/**</exclude>
        <exclude>**/file:/**</exclude>
        <exclude>**/SecurityAuth.audit*</exclude>
        <exclude>patchprocess/**</exclude>
      </excludes>
    </fileSet>
  </fileSets>
</assembly>

我们可以参考:https://maven.apache.org/plugins/maven-assembly-plugin/assembly.html看到assembly相关的所有配置。

配置项 配置 说明
id hadoop-src 设置Assembly的id。
formats/format* tar.gz 指定assembly的最终格式。这里hadoop配置的是tar.gz,表示最终打包出来一个tar.gz文件,当然可以配置多个。例如:zip、tar、jar等。
includeBaseDirectory true 在tar.gz中包括一个base目录。就是tar.gz会包含一个文件夹。而不是直接把大量的文件直接放在tar.gz中。(这个一定要配置true,不然解压安装的时候会很蛋疼。)
fileSets fileset 指定要包含在Assembly中的模块文件。就是最终要将哪些文件复制到tar.gz中。
fileset/useDefaultExcludes true 是否应使用标准排除模式。对于向后兼容性,默认值为true。
fileset/directory . 设置模块目录中的绝对或相对位置。例如,“src/main/bin”将选择定义此依赖项的项目的子目录。该目录配置表示要打包哪个目录下的文件。
includes/include* LICENCE.txt 定义一组要包含的文件和目录。如果没有配置,表示所有target内容
excludes/exclude* **/.settings 定义一组要排除的文件和目录。

制作一个属于我们自己的打包程序

需求

我们通过编写一个简单的代码,然后将代码打包成类似于Apache的软件包。代码非常简单:

public class HelloMaven {
    public static void main(String[] args) {
        System.out.println("Hello! Maven Assembly Plugin!");
    }
}

有一个配置文件,我们也需要打包:

version=1.1.0

添加一个测试依赖

在pom.xml中添加以下:

<dependencies>
    <dependency>
        <groupId>commons-cli</groupId>
        <artifactId>commons-cli</artifactId>
        <version>1.2</version>
    </dependency>
</dependencies>

一会我们会用shade插件,将该依赖直接打成uber-jar。

配置shade插件

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>3.1.1</version>
    <executions>
        <!-- Run shade goal on package phase -->
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
            <configuration>
                <filters>
                    <filter>
                        <artifact>*:*</artifact>
                        <excludes>
                            <exclude>META-INF/*.SF</exclude>
                            <exclude>META-INF/*.DSA</exclude>
                            <exclude>META-INF/*.RSA</exclude>
                            <exclude>shell-scripts/*</exclude>
                        </excludes>
                    </filter>
                </filters>
                <transformers>
                    <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                        <mainClass>cn.monkey.HelloMaven</mainClass>
                    </transformer>
                </transformers>
            </configuration>
        </execution>
    </executions>
</plugin>

执行package时,会先执行maven-jar-plugin。然后就会执行shade插件了。注意:因为我们一会要使用assembly打包,将shade打包的user-jar直接打进tar.gz。所以,shade要配置在assembly插件之前。

注意配置mainClass,也就是JAR的运行主类

配置Assembly插件

配置Maven pom.xml

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-assembly-plugin</artifactId>
    <inherited>false</inherited>
    <executions>
        <execution>
            <id>assembly-test</id>
            <phase>package</phase>
            <goals>
                <goal>single</goal>
            </goals>
            <configuration>
                <appendAssemblyId>false</appendAssemblyId>
                <attach>false</attach>
                <finalName>${project.artifactId}-bin</finalName>
                <outputDirectory>${project.build.directory}</outputDirectory>
                <!-- Not using descriptorRef and hadoop-assembly dependency -->
                <!-- to avoid making hadoop-main to depend on a module      -->
                <descriptors>
                    <descriptor>test-assemblies/test-descriptor.xml</descriptor>
                </descriptors>
            </configuration>
        </execution>
    </executions>
</plugin>
  • finalName为最终打包的文件名,此处为artifactId加上bin后缀
  • outputDirectory配置为Maven默认的输出目录,也就是一会打包完会自动在target目录生成tar.gz

配置assembly descriptor

<assembly xmlns="http://maven.apache.org/ASSEMBLY/2.1.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/ASSEMBLY/2.1.0 http://maven.apache.org/xsd/assembly-2.1.0.xsd">
<id>assembly-test</id>
<formats>
    <format>tar.gz</format>
</formats>
<fileSets>
    <fileSet>
        <directory>${project.build.directory}</directory>
        <useDefaultExcludes></useDefaultExcludes>
        <outputDirectory>lib</outputDirectory>
        <includes>
            <include>*-shaded.jar</include>
        </includes>
    </fileSet>
    <fileSet>
        <directory>${project.build.directory}/classes</directory>
        <outputDirectory>conf</outputDirectory>
        <includes>
            <include>**/config.properties</include>
        </includes>
    </fileSet>
    <fileSet>
        <directory>${project.build.directory}/classes/shell-scripts</directory>
        <outputDirectory>bin</outputDirectory>
        <fileMode>755</fileMode>
        <includes>
            <include>**/start.sh</include>
        </includes>
    </fileSet>
</fileSets>
</assembly>
  • 我们最终的文件以tar.gz方式打包
  • 第一个fileset为打包lib,我们最终的程序以jar包形式存放在tar.gz的lib文件夹中
  • 第二个fileset打包配置文件,这里直接打包config.properties
  • 第三个fileset打包运行的shell脚本,并且配置了755可执行权限

创建运行脚本

在main目录中添加shell-scripts/start.sh,要执行程序直接执行start.sh即可

#!/bin/bash
java -jar lib/${artifact.name}

配置资源打包

<build>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*</include>
            </includes>
        </resource>
        <resource>
            <targetPath>${project.build.outputDirectory}/shell-scripts</targetPath>
            <directory>src/main/shell-scripts</directory>
            <filtering>true</filtering>
            <includes>
                <include>**/*</include>
            </includes>
        </resource>
    </resources>
    ....
</build>

我们需要对shell-scriptrs下的脚本进行变量替换。

配置profile

<project>
	<profiles>
        <profile>
            <id>pro</id>
            <properties>
                <artifact.name>${project.artifactId}-${project.version}-shaded.jar</artifact.name>
            </properties>
            <activation>
                <!-- 默认激活该profile -->
                <activeByDefault>true</activeByDefault>
            </activation>
        </profile>
    </profiles>
</project>

此处配置默认的Profile为pro,当打包时会用artifact.name属性直接对shell-script中的脚本进行替换。

执行打包

我把Maven的执行过程给大家解析一遍。

# 注意此处自动指定了profile为pro

C:\opt\jdk1.8.0_241\bin\java.exe -Dmaven.multiModuleProjectDirectory=C:\Users\China\Desktop\assembly-test -Dmaven.multiModuleProjectDirectory=$MAVEN_HOME -Dmaven.wagon.http.ssl.insecure=true -Dmaven.wagon.http.ssl.allowall=true -Dmaven.wagon.http.ssl.ignore.validity.dates=true -Dmaven.home=C:\Java\apache-maven-3.5.0 -Dclassworlds.conf=C:\Java\apache-maven-3.5.0\bin\m2.conf "-Dmaven.ext.class.path=C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2020.3.2\plugins\maven\lib\maven-event-listener.jar" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2020.3.2\lib\idea_rt.jar=58840:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2020.3.2\bin" -Dfile.encoding=UTF-8 -classpath C:\Java\apache-maven-3.5.0\boot\plexus-classworlds-2.5.2.jar org.codehaus.classworlds.Launcher -Didea.version=2020.3.2 package -P pro
[INFO] Scanning for projects...
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] Building assembly-test 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 

# 拷贝resoource资源文件
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ assembly-test ---
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] Copying 1 resource
[INFO] Copying 1 resource to C:\Users\China\Desktop\assembly-test\target\classes/shell-scripts
[INFO] 

# 执行编译插件
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ assembly-test ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 

# 执行test资源拷贝,当前为空
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ assembly-test ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory C:\Users\China\Desktop\assembly-test\src\test\resources
[INFO] 

# 执行编译测试用例代码
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ assembly-test ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 

# 执行单元测试
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ assembly-test ---
[INFO] No tests to run.
[INFO] 

# 执行Maven的默认jar打包
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ assembly-test ---
[INFO] Building jar: C:\Users\China\Desktop\assembly-test\target\assembly-test-1.0-SNAPSHOT.jar
[INFO] 

# 执行shade插件打包
[INFO] --- maven-shade-plugin:3.1.1:shade (default) @ assembly-test ---
[INFO] Including commons-cli:commons-cli:jar:1.2 in the shaded jar.
[INFO] Replacing original artifact with shaded artifact.
[INFO] Replacing C:\Users\China\Desktop\assembly-test\target\assembly-test-1.0-SNAPSHOT.jar with C:\Users\China\Desktop\assembly-test\target\assembly-test-1.0-SNAPSHOT-shaded.jar
[INFO] Dependency-reduced POM written at: C:\Users\China\Desktop\assembly-test\dependency-reduced-pom.xml
[INFO] 

# 执行assembly插件打包
[INFO] --- maven-assembly-plugin:2.2-beta-5:single (assembly-test) @ assembly-test ---
[INFO] Reading assembly descriptor: test-assemblies/test-descriptor.xml
[INFO] Building tar : C:\Users\China\Desktop\assembly-test\target\assembly-test-bin.tar.gz
[WARNING] Assembly file: C:\Users\China\Desktop\assembly-test\target\assembly-test-bin.tar.gz is not a regular file (it may be a directory). It cannot be attached to the project build for installation or deployment.

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.202 s
[INFO] Finished at: 2021-02-06T21:19:21+08:00
[INFO] Final Memory: 15M/491M
[INFO] ------------------------------------------------------------------------

Process finished with exit code 0

是不是一目了然?

一顿操作后,我们发现确实打包成了tar.gz了。

用压缩软件打开看一下:

全部都已经打包好了。而且shell脚本已经进行了变量替换。

在Linux上部署

# 上传到Linux服务器
[root@compile assembly-test]# ll
总用量 40
-rw-r--r--. 1 root root 39611 2月   6 21:19 assembly-test-bin.tar.gz

# 解压
[root@compile assembly-test]# tar -xvzf assembly-test-bin.tar.gz 
assembly-test-bin/lib/assembly-test-1.0-SNAPSHOT-shaded.jar
assembly-test-bin/conf/config.properties
assembly-test-bin/bin/start.sh

# 执行
[root@compile assembly-test-bin]# pwd
/root/assembly-test/assembly-test-bin
[root@compile assembly-test-bin]# bin/start.sh 
Hello! Maven Assembly Plugin!

是不是很酷~这样的程序才是真正的、很正式的程序。

打包源代码

最后为了方便小伙伴们测试,我们把Maven项目的源码打包一份。还是使用assembly插件。

在Assembly中创建一个新的execution

<execution>
    <id>test-source-descriptor</id>
    <phase>compile</phase>
    <goals>
        <goal>single</goal>
    </goals>
    <configuration>
        <appendAssemblyId>false</appendAssemblyId>
        <attach>false</attach>
        <finalName>${project.artifactId}-source</finalName>
        <outputDirectory>${project.build.directory}</outputDirectory>
        <!-- Not using descriptorRef and hadoop-assembly dependency -->
        <!-- to avoid making hadoop-main to depend on a module      -->
        <descriptors>
            <descriptor>test-assemblies/test-source-descriptor.xml</descriptor>
        </descriptors>
    </configuration>
</execution>

注意:我当前配置的phase为compile,也就是编译阶段就会打包好maven的源代码.

为打包源码配置assembly descriptor

<assembly xmlns="http://maven.apache.org/ASSEMBLY/2.1.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/ASSEMBLY/2.1.0 http://maven.apache.org/xsd/assembly-2.1.0.xsd">
<id>test-source-descriptor</id>
<formats>
    <format>zip</format>
</formats>
<fileSets>
    <fileSet>
        <directory>${project.basedir}</directory>
        <useDefaultExcludes></useDefaultExcludes>
        <outputDirectory>.</outputDirectory>
        <includes>
            <include>src/**/*</include>
            <include>test-assemblies/**/*</include>
            <include>pom.xml</include>
        </includes>
    </fileSet>
</fileSets>
</assembly>

此处j将src源码目录、test-assemblies下的所有文件、以及pom.xml一块打包给小伙伴。

执行compile

[INFO] Scanning for projects...
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] Building assembly-test 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ assembly-test ---
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] Copying 1 resource
[INFO] Copying 1 resource to C:\Users\China\Desktop\assembly-test\target\classes/shell-scripts
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ assembly-test ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- maven-assembly-plugin:2.2-beta-5:single (test-source-descriptor) @ assembly-test ---
[INFO] Reading assembly descriptor: test-assemblies/test-source-descriptor.xml
[INFO] Building zip: C:\Users\China\Desktop\assembly-test\target\assembly-test-source.zip
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.274 s
[INFO] Finished at: 2021-02-06T21:38:37+08:00
[INFO] Final Memory: 13M/491M
[INFO] ------------------------------------------------------------------------

Process finished with exit code 0

大家看到assembly插件已经执行,并将代码打包好了。

大家看到了,这才是我们做为一个开发应该玩的Maven。本次的案例代码在我公众号上回复:maven-plugin即可获取下载链接。大家自取之。

我们下期再见!

以上

参考文献

[1] https://maven.apache.org/plugins/

[2] https://github.com/apache/hadoop

[3] https://maven.apache.org/guides/introduction/introduction-to-plugins.html

[4] https://github.com/apache/spark

[5] https://stackoverflow.com/questions/11947037/what-is-an-uber-jar

[6] https://docs.oracle.com/javase/8/docs/technotes/guides/jar/jar.html

[7] https://maven.apache.org/plugins/maven-assembly-plugin/index.html

[8] https://github.com/cko/predefined_maven_properties/blob/master/README.md

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