Question

我试图编写注释处理器，但似乎init方法总是被传递为空ProcessingEnvironment。我没有使用注释处理器的经验，但这似乎是不正确的行为。以下是代码：

@SupportedSourceVersion(SourceVersion.RELEASE_8)
@SupportedAnnotationTypes("*")
public class DocAnnotationProcessor extends AbstractProcessor {

    @Override
    public synchronized void init(ProcessingEnvironment processingEnvironment) {
        super.init(processingEnvironment);
    }

    @Override
    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
        processingEnv.getMessager().printMessage( javax.tools.Diagnostic.Kind.WARNING,"IT WORKS");
        return true;
    }
}

堆栈跟踪：

[ERROR] Failed to execute goal org.bsc.maven:maven-processor-plugin:3.3.2:process (process) on project flowBot: Error executing: java.lang.NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.bsc.maven:maven-processor-plugin:3.3.2:process (process) on project flowBot: Error executing
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:212)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:47)
Caused by: org.apache.maven.plugin.MojoExecutionException: Error executing
    at org.bsc.maven.plugin.processor.AbstractAnnotationProcessorMojo.execute(AbstractAnnotationProcessorMojo.java:429)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
    ... 21 more
Caused by: java.lang.RuntimeException: java.lang.NullPointerException
    at com.sun.tools.javac.main.Main.compile(Main.java:553)
    at com.sun.tools.javac.api.JavacTaskImpl.doCall(JavacTaskImpl.java:129)
    at com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:138)
    at org.bsc.maven.plugin.processor.AbstractAnnotationProcessorMojo.executeWithExceptionsHandled(AbstractAnnotationProcessorMojo.java:766)
    at org.bsc.maven.plugin.processor.AbstractAnnotationProcessorMojo.execute(AbstractAnnotationProcessorMojo.java:421)
    ... 23 more
Caused by: java.lang.NullPointerException
    at util.flowAnnotations.DocAnnotationProcessor.init(DocAnnotationProcessor.java:17)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment$ProcessorState.<init>(JavacProcessingEnvironment.java:500)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment$DiscoveredProcessors$ProcessorStateIterator.next(JavacProcessingEnvironment.java:597)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:690)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$1800(JavacProcessingEnvironment.java:91)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1035)
    at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1176)
    at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1170)
    at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:856)
    at com.sun.tools.javac.main.Main.compile(Main.java:523)
    ... 27 more

在我看来，这应该是最小的工作注释处理器。出了什么问题？

Answer 1

要添加到此主题的一些研究：

根据跟踪器，在3.3.1版本中修复了包含源和目标-1.8的likely bug。在编译您提供的源时出现故障时，插件会引发MojoExecutionException。

在plugin repository上搜索util.flowAnnotations.DocAnnotationProcessor无法获得任何结果，然后我会阅读comment by you，其中说明您正在混合使用scala / java并处理scala类。为此，您可以使用CustomProcessor覆盖BaseAbstractProcessor类的类似实现，然后像AnnotationProcessorCompiler那样处理scala代码。

很高兴知道，已经存在的像retronym/annotation-processor这样的堆栈与今天的堆栈一样，在sample processor.

中可见

在对this comment的矛盾说明中，我发现该插件取得了一些进展compatible with Java9.

注释处理器在init中抛出NullPointerException

1 个答案: