这篇文章主要介绍了Spring Boot中自定义注解+AOP实现主备库切换的相关知识,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，需要的朋友可以参考下
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
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; }
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 @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 listByTemplateOver3(@Param("templates") List templates);
总结
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