将maven-build-classpath添加到插件执行类路径

Question

我正在写一些代码生成maven-plugin.

我需要将我的项目类路径注入到我的插件执行类路径中.

我找到了这篇文章.解决方案有效,但很长.也许你们中的某个人知道开箱即用的解决方案.

Answer 1

找到答案了!

好吧,Pascal是对的,这里是基础!!

所以这是最简洁的方法(据我所知)将编译类路径添加到你的插件的执行.

以下是我的code-gen插件中的一些代码示例,它实际上是根据编译的代码生成一些模板代码.所以我首先需要编译代码,然后分析,生成一些代码,然后再次编译.

1. 使用@configurator的魔类:

   /**
    * @goal generate
    * @phase process-classes
    * @configurator include-project-dependencies
    * @requiresDependencyResolution compile+runtime
    */
   public class CodeGenMojo
           extends AbstractMojo
   {
       public void execute()
               throws MojoExecutionException
       {
            // do work....   
       }
   }
   

   请注意@configuratorjavadoc标题中的行,它对于plexus IOC容器是必不可少的,而不仅仅是另一个注释行.

2. include-project-dependencies配置器的实现.我从一些Brian Jackson那里获得了这个非常好的课程,将其添加到插件的源代码中.

   /**
    * A custom ComponentConfigurator which adds the project's runtime classpath elements
    * to the
    *
    * @author Brian Jackson
    * @since Aug 1, 2008 3:04:17 PM
    *
    * @plexus.component role="org.codehaus.plexus.component.configurator.ComponentConfigurator"
    *                   role-hint="include-project-dependencies"
    * @plexus.requirement role="org.codehaus.plexus.component.configurator.converters.lookup.ConverterLookup"
    *                   role-hint="default"
    */
   public class IncludeProjectDependenciesComponentConfigurator extends AbstractComponentConfigurator { 
   
       private static final Logger LOGGER = Logger.getLogger(IncludeProjectDependenciesComponentConfigurator.class);
   
       public void configureComponent( Object component, PlexusConfiguration configuration,
                                       ExpressionEvaluator expressionEvaluator, ClassRealm containerRealm,
                                       ConfigurationListener listener )
           throws ComponentConfigurationException {
   
           addProjectDependenciesToClassRealm(expressionEvaluator, containerRealm);
   
           converterLookup.registerConverter( new ClassRealmConverter( containerRealm ) );
   
           ObjectWithFieldsConverter converter = new ObjectWithFieldsConverter();
   
           converter.processConfiguration( converterLookup, component, containerRealm.getClassLoader(), configuration,
                                           expressionEvaluator, listener );
       }
   
       private void addProjectDependenciesToClassRealm(ExpressionEvaluator expressionEvaluator, ClassRealm containerRealm) throws ComponentConfigurationException {
           List<String> runtimeClasspathElements;
           try {
               //noinspection unchecked
               runtimeClasspathElements = (List<String>) expressionEvaluator.evaluate("${project.runtimeClasspathElements}");
           } catch (ExpressionEvaluationException e) {
               throw new ComponentConfigurationException("There was a problem evaluating: ${project.runtimeClasspathElements}", e);
           }
   
           // Add the project dependencies to the ClassRealm
           final URL[] urls = buildURLs(runtimeClasspathElements);
           for (URL url : urls) {
               containerRealm.addConstituent(url);
           }
       }
   
       private URL[] buildURLs(List<String> runtimeClasspathElements) throws ComponentConfigurationException {
           // Add the projects classes and dependencies
           List<URL> urls = new ArrayList<URL>(runtimeClasspathElements.size());
           for (String element : runtimeClasspathElements) {
               try {
                   final URL url = new File(element).toURI().toURL();
                   urls.add(url);
                   if (LOGGER.isDebugEnabled()) {
                       LOGGER.debug("Added to project class loader: " + url);
                   }
               } catch (MalformedURLException e) {
                   throw new ComponentConfigurationException("Unable to access project dependency: " + element, e);
               }
           }
   
           // Add the plugin's dependencies (so Trove stuff works if Trove isn't on
           return urls.toArray(new URL[urls.size()]);
       }
   
   }
   

3. 这是我必须添加的插件的构建部分.

   <modelVersion>4.0.0</modelVersion>
   <groupId>com.delver</groupId>
   <artifactId>reference-gen-plugin</artifactId>
   <name>Reference Code Genration Maven Plugin</name>
   
   <packaging>maven-plugin</packaging>
   <version>1.2</version>
   
   <url>http://maven.apache.org</url>
   
   <properties>
       <maven.version>2.2.1</maven.version>
   </properties>
   
   <build>
       <plugins>
           <plugin>
               <groupId>org.codehaus.plexus</groupId>
               <artifactId>plexus-maven-plugin</artifactId>
               <executions>
                   <execution>
                       <goals>
                           <goal>descriptor</goal>
                       </goals>
                   </execution>
               </executions>
           </plugin>
       </plugins>
   </build>
   <dependencies>
   
       <dependency>
           <groupId>org.apache.maven</groupId>
           <artifactId>maven-artifact</artifactId>
           <version>${maven.version}</version>
       </dependency>
       <dependency>
           <groupId>org.apache.maven</groupId>
           <artifactId>maven-plugin-api</artifactId>
           <version>${maven.version}</version>
       </dependency>
       <dependency>
           <groupId>org.apache.maven</groupId>
           <artifactId>maven-project</artifactId>
           <version>${maven.version}</version>
       </dependency>
       <dependency>
           <groupId>org.apache.maven</groupId>
           <artifactId>maven-model</artifactId>
           <version>${maven.version}</version>
       </dependency>
       <dependency>
           <groupId>org.apache.maven</groupId>
           <artifactId>maven-core</artifactId>
           <version>2.0.9</version>
       </dependency>
   
   </dependencies>
   

   这是需要它的人的插件的pom.xml.现在应该编译没有问题.(标题出错了,所以忽略它)

Answer 2

我采用了这种方法,显然它正在起作用:

1 - Mojo类中需要MavenProject参数:

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

2 - 然后你可以从项目实例中获取classpath元素:

try {
    Set<URL> urls = new HashSet<>();
    List<String> elements = project.getTestClasspathElements();
                                  //getRuntimeClasspathElements()
                                  //getCompileClasspathElements()
                                  //getSystemClasspathElements()  
    for (String element : elements) {
        urls.add(new File(element).toURI().toURL());
    }

    ClassLoader contextClassLoader = URLClassLoader.newInstance(
            urls.toArray(new URL[0]),
            Thread.currentThread().getContextClassLoader());

    Thread.currentThread().setContextClassLoader(contextClassLoader);

} catch (DependencyResolutionRequiredException e) {
    throw new RuntimeException(e);
} catch (MalformedURLException e) {
    throw new RuntimeException(e);
}