故障转移注解

1.注解

package com.jun.webpro.common.aspect;

import java.lang.annotation.*;

/**
 * 用于出现问题后，方法切换
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
@Documented
public @interface FailOver {
    /**
     * 故障出现，切换到新的方法
     */
    String value() default "";
}

　　

2.实现

package com.jun.webpro.common.aspect.impl;

import com.jun.webpro.common.aspect.FailOver;
import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
import java.lang.reflect.Method;
import java.util.Objects;

@Aspect
@Component
@Slf4j
public class FailOverInterceptor implements ApplicationContextAware {
    private ApplicationContext applicationContext;

    /**
     * 引入spring上下文
     */
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    // 切点
    @Pointcut("@annotation(com.jun.webpro.common.aspect.FailOver)")
    public void failoverinterceptor() {
    }

    @Around(value = "failoverinterceptor()")
    public Object doAround(ProceedingJoinPoint proceedingJoinPoint) throws Exception {
        try {
            Object proceed = proceedingJoinPoint.proceed();
        } catch (Throwable throwable) {
            throwable.printStackTrace();
            Signature signature = proceedingJoinPoint.getSignature();

            // 新的方法获取到
            MethodSignature methodSignature = (MethodSignature) signature;
            Method targetMethod = methodSignature.getMethod();

            // 获取注解上的desc
            String description = targetMethod.getAnnotation(FailOver.class).value();

            // 获取对应的参数的类型
            Class[] parameterTypes = targetMethod.getParameterTypes();

            // 获取对应的参数
            Object[] args = proceedingJoinPoint.getArgs();

            String paramClass = description.substring(0, description.lastIndexOf("."));
            String methodName = description.substring(description.lastIndexOf(".") + 1);

            // 生成类和方法
            Class clazz = Class.forName(paramClass);
            Object bean = applicationContext.getBean(clazz);
            Method method = clazz.getMethod(methodName, parameterTypes);

            // 动态的生成字节码，加载到jvn中运行
            method.invoke(bean, args);
        }
        return null;
    }
}