Question

我正在玩java注释处理，以学习如何在编译时生成java代码。我创建了一个抽象处理器（使用javapoet）创建一个新类。但是我无法让它发挥作用。我在一个java类中压缩了这个例子。我做错了什么？

当我编译项目时，我得到：

Error:java: Bad service configuration file, or exception thrown while constructing Processor object: javax.annotation.processing.Processor: Provider com.mateuyabar.AnnotProc not found

这是java代码：

package com.mateuyabar;

import com.google.auto.service.AutoService;
import com.squareup.javapoet.JavaFile;
import com.squareup.javapoet.MethodSpec;
import com.squareup.javapoet.TypeSpec;

import java.io.IOException;
import java.util.Collections;
import java.util.Set;

import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.Processor;
import javax.annotation.processing.RoundEnvironment;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.TypeElement;

@AutoService(Processor.class)
public class AnnotProc extends AbstractProcessor{
    public @interface MyAnnotation {}

    @MyAnnotation
    public static void dummyForAnnotation(){}

    @Override
    public boolean process(Set<? extends TypeElement> annotations,
            RoundEnvironment env) {
        for(Element el:env.getElementsAnnotatedWith(MyAnnotation.class)){
            System.out.println(el.asType());
        }

        MethodSpec sampleMethod = MethodSpec.methodBuilder("sampleMethod").addModifiers(Modifier.PUBLIC).returns(String.class).addParameter(String.class, "param1")
                .addStatement("return $S+$N", "Welcome, ", "name").build();
        TypeSpec customerService = TypeSpec.classBuilder("MyGeneratedClass").addModifiers(Modifier.PUBLIC).addMethod(sampleMethod).build();
        JavaFile javaFile = JavaFile.builder("com.mateuyabar", customerService).build();
        try {
            javaFile.writeTo(System.out);
        } catch (IOException e) {
            e.printStackTrace();
        }

        return false;
    }

    @Override
    public Set<String> getSupportedAnnotationTypes() {
        return Collections.singleton(MyAnnotation.class.getName());
    }

    @Override
    public SourceVersion getSupportedSourceVersion() {
        return SourceVersion.latestSupported();
    }

    public static void main(String[] args){
        System.out.println(new com.mateuyabar.MyGeneratedClass().sampleMethod("a"));
    }
}

java注释处理：生成新类的问题

0 个答案: