阅读Maven项目中的Java构建路径条目

Question

阅读Maven项目中的Java构建路径条目

我有一个在其类路径(Java buildpath)中具有依赖项的项目.现在我已将其转换为maven项目并使用我自定义的Maven插件进行编译.以下将是我的POM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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.test</groupId>
  <artifactId>test</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>ear</packaging>


  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <build>
      <plugins>
         <plugin>
            <groupId>com.my.maven.plugin</groupId>
            <artifactId>my-maven-plugin</artifactId>
            <version>0.0.1</version>
            <extensions>true</extensions>
         </plugin>
      </plugins>
  </build>
</project>

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在my-maven-plugin,我已经覆盖了编译阶段 -

maven-plugin pom-

    <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>com.test</groupId>
  <artifactId>my-maven-plugin</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>maven-plugin</packaging>

  <name>my-maven-plugin</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-core</artifactId>
        <version>3.3.9</version>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-plugin-api</artifactId>
      <version>3.3.9</version>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-compat</artifactId>
      <version>3.3.9</version>
    </dependency>   
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-embedder</artifactId>
      <version>3.3.9</version>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-archiver</artifactId>
      <version>2.5</version>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.2</version>
    </dependency>
    <dependency>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-compiler-plugin</artifactId>
      <version>3.5</version>
    </dependency>
    <dependency>
      <groupId>org.apache.maven.plugin-tools</groupId>
      <artifactId>maven-plugin-annotations</artifactId>
      <version>3.4</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>org.apache.maven.surefire</groupId>
      <artifactId>maven-surefire-common</artifactId>
      <version>2.19.1</version>
    </dependency>
    <dependency>
      <groupId>org.apache.maven.surefire</groupId>
      <artifactId>surefire-api</artifactId>
      <version>2.19.1</version>
    </dependency>
    <dependency>
        <groupId>org.codehaus.plexus</groupId>
        <artifactId>plexus-component-annotations</artifactId>
        <version>1.6</version>
        <exclusions>
            <exclusion>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
       <groupId>org.apache.maven.surefire</groupId>
       <artifactId>surefire-junit47</artifactId>
       <version>2.19.1</version>
    </dependency>
  </dependencies>
</project>

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lifecycle.xml -

<?xml version="1.0" encoding="UTF-8"?>
<lifecycles>  
  <lifecycle>  
    <id>customLifeCycle</id>  
    <phases>  
      <phase>  
        <id>compile</id>  
        <executions>  
          <execution>  
            <goals>  
              <goal>mycompile</goal>  
            </goals>  
          </execution>  
        </executions>  
      </phase> 
    </phases>  
  </lifecycle>  
</lifecycles>

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components.xml中

 <?xml version="1.0" encoding="UTF-8"?>
<component-set>
  <components>
    <component>
      <role>org.apache.maven.artifact.handler.ArtifactHandler</role>
      <role-hint>ear</role-hint>
      <implementation>org.apache.maven.artifact.handler.DefaultArtifactHandler</implementation>
      <configuration>
        <type>ear</type>
        <extension>ear</extension>
        <language>java</language>
        <packaging>ear</packaging>        
      </configuration>
    </component>

   <component>
      <role>org.apache.maven.lifecycle.mapping.LifecycleMapping</role>
      <role-hint>ear</role-hint>
      <implementation>org.apache.maven.lifecycle.mapping.DefaultLifecycleMapping</implementation>
      <configuration>
        <phases>
          <process-resources>org.apache.maven.plugins:maven-resources-plugin:resources</process-resources>
          <compile>com.test:my-maven-plugin:mycompile</compile>
          <process-test-resources>org.apache.maven.plugins:maven-resources-plugin:testResources</process-test-resources>
          <test-compile>org.apache.maven.plugins:maven-compiler-plugin:testCompile</test-compile>
          <test>org.apache.maven.plugins:maven-surefire-plugin:test</test>
          <install>org.apache.maven.plugins:maven-install-plugin:install</install>
          <deploy>org.apache.maven.plugins:maven-deploy-plugin:deploy</deploy>
        </phases>
      </configuration>
    </component>
  </components>
</component-set>

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并且,重写编译mojo -

 @Mojo( name = "mycompile", defaultPhase = LifecyclePhase.COMPILE )
 public class MyCompileMojo extends AbstractMojo{

   @Parameter( defaultValue = "${project}", readonly = true, required = true )
    private MavenProject project;
    public void execute() throws MojoExecutionException, MojoFailureException {
    }
}

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现在,在编译阶段,我想要一个存在于classpath中的JAR文件列表.我怎么才能得到它？我试过以下 - 但大多数都返回目标文件夹路径和类文件夹路径

List<String> list1 = project.getCompileClasspathElements();
List<String> list2 = project.getRuntimeClasspathElements();
List<String> list3 = project.getSystemClasspathElements();
List<String> list4 = project.getTestClasspathElements();
List<Dependency> list5 = project.getCompileDependencies();
Properties list6 = project.getProperties();
List<Dependency> list7 = project.getSystemDependencies();
List<Dependency> list8 = project.getRuntimeDependencies();

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我的项目结构要编译

Answer 1

Tun*_*aki 6

您缺少的关键成分是requiresDependencyResolution，它代表将可供插件使用的依赖项集。来自Mojo API 参考：

将此 Mojo 标记为要求在执行之前解析指定类路径中的依赖项。[...] 如果注释根本不存在，那么 mojo 不得对与 Maven 项目关联的工件做出任何假设。

要访问项目的编译时依赖项，您可以使用ResolutionScope.COMPILE：

compile解析范围 = compile+ system+provided依赖关系

除此之外，还COMPILE_PLUS_RUNTIME可以访问运行时范围的依赖项，或者TEST添加测试范围的依赖项。当 Maven 插件不存在此参数时，Maven 项目的类路径元素将不可用，这就是您遇到的行为。

因此，如果您希望 Maven 插件获取当前 Maven 项目的依赖项的编译 JAR 文件列表，您可以：

@Mojo(name = "mycompile", defaultPhase = LifecyclePhase.COMPILE, requiresDependencyResolution = ResolutionScope.COMPILE)
public class MyCompileMojo extends AbstractMojo {

    @Parameter(defaultValue = "${project}", readonly = true, required = true)
    private MavenProject project;

    public void execute() throws MojoExecutionException, MojoFailureException {
        try {
            List<String> list = project.getCompileClasspathElements();
            getLog().info(list.toString());
        } catch (DependencyResolutionRequiredException e) {
            throw new MojoFailureException("Couldn't resolve compile dependencies", e);
        }
    }

}

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该方法getCompileClasspathElements()返回每个编译时依赖项的 JAR 文件的路径列表。它还将包含当前 Maven 项目的文件夹路径target/classes，因为它包含该项目已编译的主要 Java 源代码。上面的代码将简单地打印这个列表。同样，您可以将getTestClasspathElements()与一起使用ResolutionScope.TEST以获得测试范围依赖项以及编译时依赖项的列表。

如果您只需要依赖项的 JAR 文件的路径，而不需要项目本身的类，则可以使用以下方法getArtifacts()：

public void execute() throws MojoExecutionException, MojoFailureException {
    Set<Artifact> artifacts = project.getArtifacts();
    for (Artifact artifact : artifacts) {
        System.out.println(artifact.getFile());
    }
}

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请注意，要使其正常工作，您需要确保阶段compile（或test-compile）已运行。这些列表是惰性填充的。运行mvn clean test将确保插件可以访问测试范围依赖项（如果它声明了 of requiresDependencyResolution）TEST。类似地，运行mvn clean compile（以及将阶段更改为<phase>compile</phase>）将确保插件可以访问编译范围依赖项（如果它声明了 of requiresDependencyResolution）COMPILE。

几个旁注：

该文件lifecycle.xml必须位于内部src/main/resources/META-INF/maven。请注意，该文件实际上在您的设置中完全未使用，因为您没有customLifeCycle在, 中使用 new components.xml，而是覆盖ear；
该文件components.xml必须位于内部src/main/resources/META-INF/plexus。请注意，<compile>com.test:my-maven-plugin:mycompile</compile>必须与插件的组 ID 和工件 ID 相匹配；

测试项目需要像这样使用插件：

<packaging>ear</packaging> <!-- because your lifecycle mapping override ear -->
<dependencies>
  <!-- some dependencies like maven-core -->
  <dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-core</artifactId>
    <version>3.0</version>
  </dependency>
</dependencies>
<build>
  <plugins>
    <plugin>
      <groupId>com.test</groupId>
      <artifactId>my-maven-plugin</artifactId>
      <version>0.0.1-SNAPSHOT</version>
      <extensions>true</extensions>
    </plugin>
  </plugins>
</build>

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然后您可以运行mvn clean package，插件将正确打印maven-core（例如）的 JAR 文件及其依赖项的路径。

Answer 2

Wil*_*eys 0

这对我有用。

我在这里找到了它https://www.mkyong.com/java/how-to-print-out-the-current-project-classpath/

package com.mkyong.io;

import java.net.URL;
import java.net.URLClassLoader;

public class App{

    public static void main (String args[]) {

        ClassLoader cl = ClassLoader.getSystemClassLoader();
        URL[] urls = ((URLClassLoader)cl).getURLs();

        for(URL url: urls){
            System.out.println(url.getFile());
        }
    }
}

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