Java自定义注解的实现

Java自定义注解的实现,总共三步(eg.@RandomlyThrowsException)：

1.首先编写一个自定义注解@RandomlyThrowsException

package com.github.prontera;

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)

@Target({ElementType.METHOD})

public @interface RandomlyThrowsException {

}

2.编写自定义注解@RandomlyThrowsException的实现

package com.github.prontera.aspect;

import com.github.prontera.config.ManualExceptionProperties;

import com.github.prontera.exception.ManualException;

import org.aspectj.lang.ProceedingJoinPoint;

import org.aspectj.lang.annotation.Around;

import org.aspectj.lang.annotation.Aspect;

import org.springframework.core.Ordered;

import java.security.SecureRandom;

import java.util.Random;

@Aspect

public class ManualExceptionAspect implements Ordered {

    private final int order;

    private final ManualExceptionProperties properties;

    private static final Random RANDOM = new SecureRandom();

    public ManualExceptionAspect(int order, ManualExceptionProperties properties) {

        this.order = order;

        this.properties = properties;

    }

    @Around("@annotation(com.github.prontera.RandomlyThrowsException)")

    public Object aroundMethod(ProceedingJoinPoint joinPoint) throws Throwable {

        if (properties.isEnabled()) {

            if (RANDOM.nextInt(100) % properties.getFactor() == 0) {

                throw new ManualException("manual exception");

            }

        }

        return joinPoint.proceed();

    }

    @Override

    public int getOrder() {

        return order;

    }

}

3.使用自定义注解@RandomlyThrowsException

    @Delay

    @RandomlyThrowsException

    @ApiOperation(value = "下单", notes = "生成预订单")

    @RequestMapping(value = "/orders", method = RequestMethod.POST)

    public ObjectDataResponse<Order> placeOrder(@Valid @RequestBody PlaceOrderRequest request, BindingResult result) {

        return orderService.placeOrder(request);

    }