springboot中获取指定包下的包含某个注解的全部类（转）

来自：https://www.cnblogs.com/lexiaoyao1995/p/13943784.html

需求

获取spring项目里的带有某个注解的全部类

难点
需要扫描指定包路径下的类，同时也要扫描其下所有子包

思路

可以自己实现，推荐使用spring的工具类

代码

package com.example.demo;

import com.example.demo.annos.MyAnno;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
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.test.context.junit4.SpringRunner;
import org.springframework.util.ClassUtils;

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

@RunWith(SpringRunner.class)
@SpringBootTest
public class DemoApplicationTests {

    private final String BASE_PACKAGE = "com.example.demo";
    private final String RESOURCE_PATTERN = "/**/*.class";

    @Test
    public void test() {
        Map<String, Class> handlerMap = new HashMap<String, Class>();

        //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
                MyAnno anno = clazz.getAnnotation(MyAnno.class);
                if (anno != null) {
                    //将注解中的类型值作为key，对应的类作为 value
                    handlerMap.put(classname, clazz);
                }
            }
        } catch (IOException | ClassNotFoundException e) {
        }
    }

}