自定义注解

package com.demo.anno;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

 

@Documented
@Target({ElementType.TYPE, ElementType.METHOD})//该注解只能写在类上
@Retention(RetentionPolicy.RUNTIME)//停留在源码阶段
@Inherited//继承
public @interface MyAnnotation {

    String name() default "";

    String value() default "";

    String message() default "";

}

获取注解工具类

/*
 * 版权所有 2009-2022山东新北洋信息技术股份有限公司 保留所有权利。
 */
package com.demo.anno;


import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.core.type.classreading.MetadataReaderFactory;
import org.springframework.util.ClassUtils;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

 
public class MyAnnoUtil {

    // 注解扫描包
    private static final String BASE_PACKAGE = "com.demo.service.impl";

    private static final String RESOURCE_PATTERN = "/**/*.class";

    public static List<Map<String, String>> ANNO_LIST = new ArrayList<>();

    static {
        //spring工具类，可以获取指定路径下的全部类
        ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
        try {
            String pattern = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
                    ClassUtils.convertClassNameToResourcePath(BASE_PACKAGE) + RESOURCE_PATTERN;
            Resource[] resources = resourcePatternResolver.getResources(pattern);
            //MetadataReader 的工厂类
            MetadataReaderFactory readerfactory = new CachingMetadataReaderFactory(resourcePatternResolver);
            for (Resource resource : resources) {
                //用于读取类信息
                MetadataReader reader = readerfactory.getMetadataReader(resource);
                //扫描到的class
                String classname = reader.getClassMetadata().getClassName();
                Class<?> clazz = Class.forName(classname);
                //判断是否有指定主解
                MyAnnotation anno = clazz.getAnnotation(MyAnnotation.class);
                if (anno != null) {
                    //将注解中的类型值作为key，对应的类作为 value
                    HashMap<String, String> annoMap = new HashMap<>();
                    annoMap.put("name", anno.name());
                    annoMap.put("value", anno.value());
                    annoMap.put("message", anno.message());
                    ANNO_LIST.add(annoMap);
                }
            }
        } catch (IOException | ClassNotFoundException e) {
            throw e;
        }
    }

}