Java注解与反射解析类信息详解

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
public @interface Description {
    String value();
    String author() default "unknown";
}

@Description("用户服务类")
public class UserService {

    @Description(value = "保存用户", author = "zhangsan")
    public void saveUser() {
        System.out.println("保存用户...");
    }

    public void deleteUser() {
        System.out.println("删除用户...");
    }
}

public class AnnotationParser {
    public static void parse(Class clazz) {
        // 判断类是否有 Description 注解
        if (clazz.isAnnotationPresent(Description.class)) {
            Description desc = clazz.getAnnotation(Description.class);
            System.out.println("类描述: " + desc.value());
            System.out.println("作者: " + desc.author());
        }

        // 遍历所有方法，检查是否有 Description 注解
        for (java.lang.reflect.Method method : clazz.getDeclaredMethods()) {
            if (method.isAnnotationPresent(Description.class)) {
                Description desc = method.getAnnotation(Description.class);
                System.out.println("方法: " + method.getName() + 
                                 ", 描述: " + desc.value() + 
                                 ", 作者: " + desc.author());
            }
        }
    }

    public static void main(String[] args) {
        parse(UserService.class);
    }
}