Spring Boot中自定义注解+AOP实现主备库切换

摘要: 本篇文章的场景是做调度中心和监控中心时的需求，后端使用TDDL实现分表分库，需求:实现关键业务的查询监控,当用Mybatis查询数据时需要从主库切换到备库或者直接连到备库上查询,从而减小主库的压力，在本篇文章中主要记录在Spring Boot中通过自定义注解结合AOP实现直接连接备库查询。

一.通过AOP 自定义注解实现主库到备库的切换

1.1 自定义注解

自定义注解如下代码所示

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 SwitchDataBase {

    boolean switch2Backup() default false;

}

1.2 实现方法拦截器对自定义注解处理

import java.lang.reflect.Method;

import java.util.Arrays;

import org.aopalliance.intercept.MethodInterceptor;

import org.aopalliance.intercept.MethodInvocation;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.stereotype.Component;

/**

 * 处理走备库逻辑的注解

 */

@Component

public class SwitchDataBaseInterceptor implements MethodInterceptor {

    private final Logger log = LoggerFactory.getLogger(SwitchDataBaseInterceptor.class);

    @Override

    public Object invoke(MethodInvocation invocation) throws Throwable {

        Method method = invocation.getMethod();

        SwitchDataBase annotation = getAnnotation(method);

        if (annotation == null) {

            return invocation.proceed();

        }

        Object val = null;

        if(!ThreadLocalMap.containsKey(GroupDataSourceRouteHelper.DATASOURCE_INDEX)) {

            if (annotation.switch2Backup()) {

                log.info("query back up DB, method: " + method.getName());

                GroupDataSourceRouteHelper.executeByGroupDataSourceIndex(1, true);

            } else {

                log.info("query primary DB, method: " + method.getName());

                GroupDataSourceRouteHelper.executeByGroupDataSourceIndex(0, true);

            }

        }

        try {

            val = invocation.proceed();

        } catch (Exception e) {

            log.info(method.getDeclaringClass().getName() + "." +

                    invocation.getMethod().getName() + "方法调用失败，arguments：" +

                    Arrays.toString(invocation.getArguments()));

            throw new RuntimeException(e);

        } finally {

            GroupDataSourceRouteHelper.removeGroupDataSourceIndex();

        }

        return val;

    }

    /**

     * 找方法上面声明的注解

     */

    private SwitchDataBase getAnnotation(Method method) {

        if (method.isAnnotationPresent(SwitchDataBase.class)) {

            return method.getAnnotation(SwitchDataBase.class);

        }

        return null;

    }

}

1.3 配置OverallQueryConfiguration

在Spring Boot中装配AOP Bean，实现扫描特定目录下的注解，实现切面变成形成通知处理。示例代码如下

import com.wdk.wms.annotation.SwitchDataBaseInterceptor;

import org.springframework.aop.Advisor;

import org.springframework.aop.support.DefaultPointcutAdvisor;

import org.springframework.aop.support.JdkRegexpMethodPointcut;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

@Configuration

public class SwitchDataBaseConfiguration {

    @Bean(name = "overallQueryInterceptor")

    public SwitchDataBaseInterceptor overallQueryInterceptor() {

        return new SwitchDataBaseInterceptor();

    }

    //添加aop的pointcut

    @Bean(name = "jdkRegexpMethodPointcut")

    public JdkRegexpMethodPointcut jdkRegexpMethodPointcut() {

        JdkRegexpMethodPointcut jdkRegexpMethodPointcut = new JdkRegexpMethodPointcut();

        jdkRegexpMethodPointcut.setPatterns("com.wdk.wms.mapper.*");

        return jdkRegexpMethodPointcut;

    }

    //设置默认的aop配置对应的是原来的<aop:advisor>

    @Bean

    public Advisor druidAdvisor() {

        DefaultPointcutAdvisor defaultPointcutAdvisor = new DefaultPointcutAdvisor();

        defaultPointcutAdvisor.setPointcut(jdkRegexpMethodPointcut());

        defaultPointcutAdvisor.setAdvice(overallQueryInterceptor());

        return defaultPointcutAdvisor;

    }

}

1.4 如何使用注解从主库到备库的切换

@SwitchDataBase(switch2Backup = true)

List<ConsumerNoticeMsg> listByTemplateOver3(@Param("templates") List<Integer> templates);

Spring Boot中自定义注解+AOP实现主备库切换的相关教程结束。