【动态多数据源】spring boot mybatis

作者: 植富宝 | 来源:发表于2019-02-27 19:41 被阅读0次

Spring Boot集成Mybatis双数据源
mybatis多数据源配置并初始化数据库
Spring Boot Mybatis集成
Spring Boot中动态数据源切换
SpringBoot整合mybatis-plus和druid配置
Day 3
spring-boot-mybatis-generator-pa
Spring boot + Mybatis 整合（Intelli
mybatis和spring boot集成的源码分析（一）
解析配置文件自动装配 DataSource + Abstract

概述

spring boot + mybatis 实现动态多数据源，本文讲解一写两读，更多的配置一样
前提：需要做好mysql的主从同步功能
实现的动态数据源的代码，主要在包conf中
DataSourceConfigurer.java ====> 数据源配置类
DataSourceKey.java ====> 数据源key类
DynamicDataSourceAspect.java ====> AOP切面类
DynamicDataSourceContextHolder.java ====> 切换数据源类
DynamicRoutingDataSource.java ====> 数据源路由类

DataSourceConfigurer.java

package com.example.demo.conf;

import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;

import javax.sql.DataSource;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

/**
 * 数据源配置
 */
@Configuration
@MapperScan(basePackages = DataSourceConfigurer.PACKAGE)
public class DataSourceConfigurer {

    // 精确到 first 目录，以便跟其他数据源隔离
    static final String PACKAGE = "com.example.demo.dao";
    static final String MAPPER_LOCATION = "classpath:mapper/*.xml";

    @Bean("first")
    @Primary
    @ConfigurationProperties(prefix = "first.datasource")
    public DataSource first() {
        return DruidDataSourceBuilder.create().build();
    }

    @Bean("second")
    @ConfigurationProperties(prefix = "second.datasource")
    public DataSource second() {
        return DruidDataSourceBuilder.create().build();
    }

    @Bean("third")
    @ConfigurationProperties(prefix = "third.datasource")
    public DataSource third() {
        return DruidDataSourceBuilder.create().build();
    }

    @Bean("dynamicDataSource")
    public DataSource dynamicDataSource() {
        DynamicRoutingDataSource dynamicRoutingDataSource = new DynamicRoutingDataSource();
        Map<Object, Object> dataSourceMap = new HashMap<>(3);
        dataSourceMap.put(DataSourceKey.first.name(), first());
        dataSourceMap.put(DataSourceKey.second.name(), second());
        dataSourceMap.put(DataSourceKey.third.name(), third());

        // 将 first 数据源作为默认指定的数据源
        dynamicRoutingDataSource.setDefaultTargetDataSource(first());

        // 将 first second third 数据源作为指定的数据源
        dynamicRoutingDataSource.setTargetDataSources(dataSourceMap);

        // 将数据源的 key 放到数据源上下文的 key 集合中，用于切换时判断数据源是否有效
        DynamicDataSourceContextHolder.dataSourceKeys.addAll(dataSourceMap.keySet());

        // 将 second third 数据源的 key 放在集合中，用于轮循
        DynamicDataSourceContextHolder.slaveDataSourceKeys.addAll(dataSourceMap.keySet());
        DynamicDataSourceContextHolder.slaveDataSourceKeys.remove(DataSourceKey.first.name());

        return dynamicRoutingDataSource;
    }

    /**
     * 配置 SqlSessionFactoryBean
     * @ConfigurationProperties 在这里是为了将 MyBatis 的 mapper 位置和持久层接口的别名设置到
     * Bean 的属性中，如果没有使用 *.xml 则可以不用该配置，否则将会产生 invalid bond statement 异常
     */
    @Bean
//    @ConfigurationProperties(prefix = "mybatis")
    public SqlSessionFactoryBean sqlSessionFactoryBean() throws IOException {

        // 配置数据源，此处配置为关键配置，如果没有将 dynamicDataSource 作为数据源则不能实现切换
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dynamicDataSource());
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(DataSourceConfigurer.MAPPER_LOCATION));

        return sqlSessionFactoryBean;
    }

    /**
     * 注入 DataSourceTransactionManager 用于事务管理
     * @return
     */
    @Bean
    public PlatformTransactionManager transactionManager() {
        return new DataSourceTransactionManager(dynamicDataSource());
    }
}

DataSourceKey.java

package com.example.demo.conf;

public enum DataSourceKey {
    first, second, third
}

DynamicDataSourceAspect.java

package com.example.demo.conf;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;


/**
 * 动态数据源切换的切面，切 DAO 层，通过 DAO 层方法名判断使用哪个数据源，实现数据源切换 关于切面的 Order 可以可以不设，
 * 因为 @Transactional 是最低的，取决于其他切面的设置，并且在 org.springframework.core.annotation.AnnotationAwareOrderComparator 会重新排序
 */
@Aspect
@Component
public class DynamicDataSourceAspect {
    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);

    private final String[] QUERY_PREFIX = {"get", "query", "find", "select", "is"};

    @Pointcut("execution(* com.example.demo.service.impl.*.*(..))")
    public void daoAspect() {
    }

    @Before("daoAspect()")
    public void switchDataSource(JoinPoint point) {
        logger.info("--------------------------------------------------");
        logger.info("    Class Name ----> "+ point.getTarget().getClass().getName());
        logger.info("    Method Name ----> "+ point.getSignature().getName());
        logger.info("--------------------------------------------------");

        Boolean isQueryMethod = isQueryMethod(point.getSignature().getName());
        logger.info("--------------------------------------------------");
        logger.info("    Var ----> true 从数据源, false 主数据源 ----> "+ isQueryMethod);
        logger.info("--------------------------------------------------");

        if (isQueryMethod) {
            DynamicDataSourceContextHolder.useSlaveDataSource();
            logger.debug("Switch DataSource to [{}] in Method [{}]", DynamicDataSourceContextHolder.getDataSourceKey(), point.getSignature());
        }

        if (!isQueryMethod) {
            logger.info("分割线====================================================================================================分割线");
        }
    }

    @After("daoAspect())")
    public void restoreDataSource(JoinPoint point) {
        DynamicDataSourceContextHolder.clearDataSourceKey();
        logger.debug("Restore DataSource to [{}] in Method [{}]", DynamicDataSourceContextHolder.getDataSourceKey(), point.getSignature());
    }

    private Boolean isQueryMethod(String methodName) {
        for (String prefix : QUERY_PREFIX) {
            if (methodName.startsWith(prefix)) {
                return true;
            }
        }
        return false;
    }
}

DynamicDataSourceContextHolder.java

package com.example.demo.conf;


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 该类为数据源上下文配置，用于切换数据源
 */
public class DynamicDataSourceContextHolder {

    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceContextHolder.class);

    // 用于在切换数据源时保证不会被其他线程修改
    private static Lock lock = new ReentrantLock();

    // 用于轮循的计数器
    private static int counter = 0;

    // 为每个线程维护变量，以避免影响其他线程
    private static final ThreadLocal<String> CONTEXT_HOLDER = ThreadLocal.withInitial(DataSourceKey.first::name);

    // 所有数据源key
    public static List<Object> dataSourceKeys = new ArrayList<>();

    // 从数据源key
    public static List<Object> slaveDataSourceKeys = new ArrayList<>();

    public static void setDataSourceKey(String key) {
        CONTEXT_HOLDER.set(key);
    }

    public static void useMasterDataSource() {
        CONTEXT_HOLDER.set(DataSourceKey.first.name());
    }

    public static String getDataSourceKey() {
        return CONTEXT_HOLDER.get();
    }

    public static void clearDataSourceKey() {
        CONTEXT_HOLDER.remove();
    }

    public static boolean containDataSourceKey(String key) {
        return dataSourceKeys.contains(key);
    }

    /**
     * 当使用只读数据源时通过轮循方式选择要使用的数据源
     */
    public static void useSlaveDataSource() {
        lock.lock();
        try {
            int datasourceKeyIndex = counter % slaveDataSourceKeys.size();
            CONTEXT_HOLDER.set(String.valueOf(slaveDataSourceKeys.get(datasourceKeyIndex)));
            counter++;
        } catch (Exception e) {
            logger.error("Switch slave datasource failed, error message is {}", e.getMessage());
            useMasterDataSource();
            e.printStackTrace();
        } finally {
            logger.info("--------------------------------------------------");
            logger.info("    Var ----> CONTEXT_HOLDER.get() ----> "+ CONTEXT_HOLDER.get());
            logger.info("--------------------------------------------------");
            logger.info("分割线====================================================================================================分割线");

            lock.unlock();
        }
    }
}

DynamicRoutingDataSource.java

package com.example.demo.conf;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;


public class DynamicRoutingDataSource extends AbstractRoutingDataSource {

    private final Logger logger = LoggerFactory.getLogger(getClass());

    @Override
    protected Object determineCurrentLookupKey() {
        logger.debug("Current DataSource is [{}]", DynamicDataSourceContextHolder.getDataSourceKey());
        return DynamicDataSourceContextHolder.getDataSourceKey();
    }
}

测试结果

查询
这个getDetail方法被打倒了third数据库上

2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect]     Class Name ----> com.example.demo.service.impl.UserServiceImpl
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect]     Method Name ----> getDetail
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect]     Var ----> true 从数据源, false 主数据源 ----> true
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceContextHolder] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceContextHolder]     Var ----> CONTEXT_HOLDER.get() ----> third
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceContextHolder] --------------------------------------------------
2018-05-04 15:55:40 [INFO]-[com.example.demo.conf.DynamicDataSourceContextHolder] 分割线====================================================================================================分割线

插入
这个register方法被打到了主数据源上

2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect]     Class Name ----> com.example.demo.service.impl.UserServiceImpl
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect]     Method Name ----> register
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect]     Var ----> true 从数据源, false 主数据源 ----> false
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] --------------------------------------------------
2018-05-04 16:08:30 [INFO]-[com.example.demo.conf.DynamicDataSourceAspect] 分割线====================================================================================================分割线

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