springboot动态加入注解怎么实现

要在Spring Boot中动态加入注解，可以使用Java的动态代理技术和反射机制。以下是一个示例代码，演示如何在运行时动态加入注解：

import org.springframework.beans.factory.config.BeanDefinition; import org.springframework.context.annotation.AnnotationBeanNameGenerator; import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider; import org.springframework.core.type.AnnotationMetadata; import org.springframework.core.type.filter.AnnotationTypeFilter; import org.springframework.stereotype.Component; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RequestMapping; import java.lang.annotation.Annotation; import java.lang.reflect.Method; import java.lang.reflect.Proxy; import java.util.HashSet; import java.util.Set; public class DynamicAnnotationExample { public static void main(String[] args) { // 获取所有带有@Controller注解的类 Set<Class<?>> controllerClasses = getClassesWithAnnotation(Controller.class); // 动态加入@GetMapping注解到所有方法上 for (Class<?> controllerClass : controllerClasses) { addGetMappingAnnotation(controllerClass); } } private static Set<Class<?>> getClassesWithAnnotation(Class<? extends Annotation> annotationClass) { Set<Class<?>> classes = new HashSet<>(); ClassPathScanningCandidateComponentProvider provider = new ClassPathScanningCandidateComponentProvider(false); provider.addIncludeFilter(new AnnotationTypeFilter(annotationClass)); for (BeanDefinition beanDefinition : provider.findCandidateComponents("com.example")) { try { Class<?> clazz = Class.forName(beanDefinition.getBeanClassName()); classes.add(clazz); } catch (Exception e) { e.printStackTrace(); } } return classes; } private static void addGetMappingAnnotation(Class<?> controllerClass) { Object controllerProxy = Proxy.newProxyInstance( controllerClass.getClassLoader(), new Class[]{controllerClass}, (proxy, method, args) -> { // 动态加入@GetMapping注解到方法上 AnnotationMetadata annotationMetadata = new AnnotationMetadata() { @Override public Set<String> getAnnotationTypes() { return Set.of(GetMapping.class.getName()); } @Override public Set<String> getMetaAnnotationTypes(String annotationName) { return null; } @Override public boolean hasAnnotation(String annotationName) { return GetMapping.class.getName().equals(annotationName); } @Override public boolean hasMetaAnnotation(String metaAnnotationName) { return false; } @Override public boolean isAnnotated(String annotationName) { return GetMapping.class.getName().equals(annotationName); } @Override public Map<String, Object> getAnnotationAttributes(String annotationName) { return Map.of("value", new String[]{"/dynamic"}); } @Override public Map<String, Object> getAnnotationAttributes(String annotationName, boolean classValuesAsString) { return null; } }; Method proxyMethod = Proxy.class.getDeclaredMethod("proxyMethod", Method.class); proxyMethod.setAccessible(true); Method realMethod = (Method) proxyMethod.invoke(proxy, method); Method dynamicMethod = new DynamicMethod(realMethod, annotationMetadata); return dynamicMethod.invoke(proxy, args); }); // 替换原有的Controller Bean AnnotationBeanNameGenerator generator = new AnnotationBeanNameGenerator(); String beanName = generator.generateBeanName(controllerClass, null); SpringContextHolder.replaceBean(controllerClass, beanName, controllerProxy); } // 动态代理中用于替换原有方法的动态方法 private static class DynamicMethod extends Method { private final AnnotationMetadata annotationMetadata; public DynamicMethod(Method method, AnnotationMetadata annotationMetadata) { super( method.getName(), method.getParameterTypes(), method.getReturnType(), method.getExceptionTypes(), method.getModifiers(), method.getDeclaringClass(), method.getDefaultValue() ); this.annotationMetadata = annotationMetadata; } @Override public <T extends Annotation> T getAnnotation(Class<T> annotationClass) { return annotationMetadata.isAnnotated(annotationClass.getName()) ? annotationMetadata.getAnnotationAttributes(annotationClass.getName()) : super.getAnnotation(annotationClass); } @Override public Annotation[] getAnnotations() { Annotation[] annotations = super.getAnnotations(); Map<String, Object> attributes = annotationMetadata.getAnnotationAttributes(Controller.class.getName()); List<Annotation> result = new ArrayList<>(Arrays.asList(annotations)); result.add(createGetMappingAnnotation(attributes)); return result.toArray(new Annotation[0]); } private Annotation createGetMappingAnnotation(Map<String, Object> attributes) { return new GetMapping() { @Override public Class<? extends Annotation> annotationType() { return GetMapping.class; } @Override public String[] value() {