如何使用给定的注释运行所有方法? [英] How to run all methods with a given annotation?

问题描述

这就是我想要发生的:

public class MainClass {
    public static void main(String args[]) { 
        run @mod(); // run all methods annotated with @mod annotation
    }
}

注解声明:

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface mod {
   String name() default "";
}

要调用的方法:

public class Good {
    @mod (name = "me1")
    public void calledcs(){
        System.out.println("called");
    }

    @mod (name = "me2")
    public void calledcs2(){
        System.out.println("called");
    }
}

或者有其他方法可以达到同样的目的吗?

or is there another way to achieve the same thing?

推荐答案

您可以使用类路径扫描来做到这一点:基本上，您可以检查类路径中每个类的每个方法，并使用给定的注释对所有方法进行注释.之后，您调用找到的方法.

You can do it using classpath scanning: Basically you go over every method of every class in the classpath and get all annotated with your given annotation. After that, you invoke the found methods.

下面是一个可以做到这一点的 runAllAnnotatedWith() 方法.它使用反射来完成类路径扫描的脏活.为简单起见，它执行所有找到的方法，就好像它们是静态并且不需要参数.

Below is a runAllAnnotatedWith() method that would do it. It uses Reflections to do the dirty work of classpath scanning. For simplicity, it executes all found methods as if they were static and required no parameters.

public static void runAllAnnotatedWith(Class<? extends Annotation> annotation)
                                                               throws Exception {
    Reflections reflections = new Reflections(new ConfigurationBuilder()
                                  .setUrls(ClasspathHelper.forJavaClassPath())
                                  .setScanners(new MethodAnnotationsScanner()));
    Set<Method> methods = reflections.getMethodsAnnotatedWith(annotation);

    for (Method m : methods) {
        // for simplicity, invokes methods as static without parameters
        m.invoke(null); 
    }
}

您可以使用:

runAllAnnotatedWith(mod.class);

注意:可以不使用反射，但是代码会越来越脏.

Note: It is possible to do it without using Reflections, but the code will get dirtier and dirtier.

这是完整的代码(将其全部粘贴到 RunClass.java 文件中):

Here's the full code (paste it all into a RunClass.java file):

import java.lang.annotation.Annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Method;
import java.util.Set;

import org.reflections.Reflections;
import org.reflections.scanners.MethodAnnotationsScanner;
import org.reflections.util.ClasspathHelper;
import org.reflections.util.ConfigurationBuilder;

public class RunClass {
    public static void main(String args[]) throws Exception {
        runAllAnnotatedWith(mod.class);
    }

    public static void runAllAnnotatedWith(Class<? extends Annotation> annotation) throws Exception {
        Reflections reflections = new Reflections(new ConfigurationBuilder()
                .setUrls(ClasspathHelper.forJavaClassPath()).setScanners(
                        new MethodAnnotationsScanner()));
        Set<Method> methods = reflections.getMethodsAnnotatedWith(annotation);

        for (Method m : methods) {
            m.invoke(null); // for simplicity, invoking static methods without parameters
        }
    }

    @mod(name = "me1")
    public static void calledcs() {
        System.out.println("called");
    }

    @mod(name = "me2")
    public static void calledcs2() {
        System.out.println("called2");
    }
}

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@interface mod {
    String name() default "";
}

要运行它，您必须将 Reflections JAR 添加到您的项目中.在此处下载.

To run it, you have to add the Reflections JAR to your project. Download it here.

如果你使用 Maven，你可以使用:

If you use Maven, you can add it using:

<dependency>
    <groupId>org.reflections</groupId>
    <artifactId>reflections</artifactId>
    <version>0.9.9-RC1</version>
</dependency>

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