你好，我是程序员Alan, 很快乐遇见你。
最近看 RocketMQ 源码时，发现它是应用自定义注解的形式做权限校验，蛮有意思的，于是简略上手试了一下。
上面是局部代码。
自定义注解
import java.lang.annotation.*;@Target(ElementType.METHOD)@Retention(RetentionPolicy.RUNTIME)public @interface Permission { String permission() default "";}编写切面
import org.aspectj.lang.ProceedingJoinPoint;import org.aspectj.lang.annotation.*;import org.springframework.stereotype.Component;import java.lang.reflect.Method;import org.aspectj.lang.reflect.MethodSignature;@Component@Aspectpublic class PermissionAnnotationAspect { @Pointcut("@annotation(com.esandinfo.pclogin.permission.Permission)") private void permission() { } @Around("permission()") public void advice(ProceedingJoinPoint joinPoint) throws Throwable { MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature(); Method method = methodSignature.getMethod(); if (!method.isAnnotationPresent(Permission.class)) { joinPoint.proceed(); //没有应用注解默认放行 } else { Permission permission = fetchPermission(methodSignature); //[1] 取出申请方的权限信息 String userPermission = "TEST"; //假如用户权限为 TEST System.out.println("用户权限: " + userPermission); //[2] 和注解的值做比拟 permission.permission() if (userPermission.equals(permission.permission())){ //[3] 校验通过放行用户 System.out.println("放行"); joinPoint.proceed(); } return; } } private Permission fetchPermission(MethodSignature methodSignature) { return methodSignature.getMethod().getAnnotation(Permission.class); }}测试
import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class PermissionAnnotationController { @RequestMapping(value = "/public/testMethod") @Permission(permission = "TEST") public void testMethod(){ }}