MyBatis双数据源配置

时间：2023-12-27 19:22:37

配置相关

jdbc 配置

#============================================================================

# MySQL

#============================================================================

jdbc.mysql.driver=com.mysql.jdbc.Driver

jdbc.mysql.url=jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true

jdbc.mysql.username=root

jdbc.mysql.password=root

#============================================================================

# MS SQL Server (JTDS)

#============================================================================

jdbc.sqlserver.driver=net.sourceforge.jtds.jdbc.Driver

jdbc.sqlserver.url=jdbc:jtds:sqlserver://127.0.0.1:1433/test

jdbc.sqlserver.username=sa

jdbc.sqlserver.password=sa

#============================================================================

# 通用配置

#============================================================================

jdbc.initialSize=5

jdbc.minIdle=5

jdbc.maxIdle=20

jdbc.maxActive=100

jdbc.maxWait=100000

jdbc.defaultAutoCommit=false

jdbc.removeAbandoned=true

jdbc.removeAbandonedTimeout=600

jdbc.testWhileIdle=true

jdbc.timeBetweenEvictionRunsMillis=60000

jdbc.numTestsPerEvictionRun=20

jdbc.minEvictableIdleTimeMillis=300000

jdbc.properties

单数据源时的Spring配置文件

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xmlns:context="http://www.springframework.org/schema/context"

       xmlns:aop="http://www.springframework.org/schema/aop"

       xsi:schemaLocation="http://www.springframework.org/schema/beans

    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

    http://www.springframework.org/schema/context

    http://www.springframework.org/schema/context/spring-context-3.0.xsd

      http://www.springframework.org/schema/aop

          http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

        <property name="location" value="classpath:jdbc.properties"/>

    </bean>

       <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

        <property name="driverClassName" value="${jdbc.mysql.driver}"/>

        <property name="url" value="${jdbc.mysql.url}"/>

        <property name="username" value="${jdbc.mysql.username}"/>

        <property name="password" value="${jdbc.mysql.password}"/>

        <property name="initialSize" value="${jdbc.initialSize}"/>

        <property name="minIdle" value="${jdbc.minIdle}"/>

        <property name="maxIdle" value="${jdbc.maxIdle}"/>

        <property name="maxActive" value="${jdbc.maxActive}"/>

        <property name="maxWait" value="${jdbc.maxWait}"/>

        <property name="defaultAutoCommit" value="${jdbc.defaultAutoCommit}"/>

        <property name="removeAbandoned" value="${jdbc.removeAbandoned}"/>

        <property name="removeAbandonedTimeout" value="${jdbc.removeAbandonedTimeout}"/>

        <property name="testWhileIdle" value="${jdbc.testWhileIdle}"/>

        <property name="timeBetweenEvictionRunsMillis" value="${jdbc.timeBetweenEvictionRunsMillis}"/>

        <property name="numTestsPerEvictionRun" value="${jdbc.numTestsPerEvictionRun}"/>

        <property name="minEvictableIdleTimeMillis" value="${jdbc.minEvictableIdleTimeMillis}"/>

    </bean>

    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">

        <property name="dataSource" ref="dataSource"/>

    </bean>

    <!-- mybatis.spring自动映射 -->

    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">

        <property name="basePackage" value="com.cnblogs.lzrabbit"/>

    </bean>

    <!-- 自动扫描，多个包以 逗号分隔 -->

    <context:component-scan base-package="com.cnblogs.lzrabbit"/>

    <aop:aspectj-autoproxy/>

</beans>

applicationContext.xml

多数据源时Spring配置文件

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xmlns:context="http://www.springframework.org/schema/context"

       xmlns:aop="http://www.springframework.org/schema/aop"

       xsi:schemaLocation="http://www.springframework.org/schema/beans

    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

    http://www.springframework.org/schema/context

    http://www.springframework.org/schema/context/spring-context-3.0.xsd

      http://www.springframework.org/schema/aop

          http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

        <property name="location" value="classpath:jdbc.properties"/>

    </bean>

    <bean id="sqlServerDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

        <property name="driverClassName" value="${jdbc.sqlserver.driver}"/>

        <property name="url" value="${jdbc.sqlserver.url}"/>

        <property name="username" value="${jdbc.sqlserver.username}"/>

        <property name="password" value="${jdbc.sqlserver.password}"/>

        <property name="initialSize" value="${jdbc.initialSize}"/>

        <property name="minIdle" value="${jdbc.minIdle}"/>

        <property name="maxIdle" value="${jdbc.maxIdle}"/>

        <property name="maxActive" value="${jdbc.maxActive}"/>

        <property name="maxWait" value="${jdbc.maxWait}"/>

        <property name="defaultAutoCommit" value="${jdbc.defaultAutoCommit}"/>

        <property name="removeAbandoned" value="${jdbc.removeAbandoned}"/>

        <property name="removeAbandonedTimeout" value="${jdbc.removeAbandonedTimeout}"/>

        <property name="testWhileIdle" value="${jdbc.testWhileIdle}"/>

        <property name="timeBetweenEvictionRunsMillis" value="${jdbc.timeBetweenEvictionRunsMillis}"/>

        <property name="numTestsPerEvictionRun" value="${jdbc.numTestsPerEvictionRun}"/>

        <property name="minEvictableIdleTimeMillis" value="${jdbc.minEvictableIdleTimeMillis}"/>

    </bean>

    <bean id="mySqlDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

        <property name="driverClassName" value="${jdbc.mysql.driver}"/>

        <property name="url" value="${jdbc.mysql.url}"/>

        <property name="username" value="${jdbc.mysql.username}"/>

        <property name="password" value="${jdbc.mysql.password}"/>

        <property name="initialSize" value="${jdbc.initialSize}"/>

        <property name="minIdle" value="${jdbc.minIdle}"/>

        <property name="maxIdle" value="${jdbc.maxIdle}"/>

        <property name="maxActive" value="${jdbc.maxActive}"/>

        <property name="maxWait" value="${jdbc.maxWait}"/>

        <property name="defaultAutoCommit" value="${jdbc.defaultAutoCommit}"/>

        <property name="removeAbandoned" value="${jdbc.removeAbandoned}"/>

        <property name="removeAbandonedTimeout" value="${jdbc.removeAbandonedTimeout}"/>

        <property name="testWhileIdle" value="${jdbc.testWhileIdle}"/>

        <property name="timeBetweenEvictionRunsMillis" value="${jdbc.timeBetweenEvictionRunsMillis}"/>

        <property name="numTestsPerEvictionRun" value="${jdbc.numTestsPerEvictionRun}"/>

        <property name="minEvictableIdleTimeMillis" value="${jdbc.minEvictableIdleTimeMillis}"/>

    </bean>

    <bean id="multipleDataSource" class="com.cnblogs.lzrabbit.MultipleDataSource">

        <property name="defaultTargetDataSource" ref="mySqlDataSource"/>

        <property name="targetDataSources">

            <map>

                <entry key="mySqlDataSource" value-ref="mySqlDataSource"/>

                <entry key="sqlServerDataSource" value-ref="sqlServerDataSource"/>

            </map>

        </property>

    </bean>

    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">

        <property name="dataSource" ref="multipleDataSource"/>

    </bean>

    <!-- mybatis.spring自动映射 -->

    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">

        <property name="basePackage" value="com.cnblogs.lzrabbit"/>

    </bean>

    <!-- 自动扫描，多个包以 逗号分隔 -->

    <context:component-scan base-package="com.cnblogs.lzrabbit"/>

    <aop:aspectj-autoproxy/>

</beans>

MultipleDataSource实现

package com.cnblogs.lzrabbit;

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

/**

 * Created by rabbit on 14-5-25.

 */

public class MultipleDataSource extends AbstractRoutingDataSource {

    private static final ThreadLocal<String> dataSourceKey = new InheritableThreadLocal<String>();

    public static void setDataSourceKey(String dataSource) {

        dataSourceKey.set(dataSource);

    }

    @Override

    protected Object determineCurrentLookupKey() {

        return dataSourceKey.get();

    }

}

手动数据源切换调用

package com.cnblogs.lzrabbit;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

/**

 * Created by rabbit on 14-5-25.

 */

public class Main {

    public static void main(String[] args) {

        //初始化ApplicationContext

        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");

        MySqlMapper mySqlMapper = applicationContext.getBean(MySqlMapper.class);

        SqlServerMapper sqlServerMapper = applicationContext.getBean(SqlServerMapper.class);

        //设置数据源为MySql,使用了AOP测试时请将下面这行注释

        MultipleDataSource.setDataSourceKey("mySqlDataSource");

        mySqlMapper.getList();

        //设置数据源为SqlServer,使用AOP测试时请将下面这行注释

        MultipleDataSource.setDataSourceKey("sqlServerDataSource");

        sqlServerMapper.getList();

    }

}

MyBatis接口Mapper定义，直接使用注解方式实现

public interface MySqlMapper {

    @Select("select * from MyTable")

    List<Map<String,Object>> getList();

}

public interface SqlServerMapper {

        @Select("select * from MyTable")

        List<Map<String,Object>> getList();

}

使用SpringAOP方式实现自动切换

package com.cnblogs.lzrabbit;

import org.aspectj.lang.ProceedingJoinPoint;

import org.aspectj.lang.annotation.Around;

import org.aspectj.lang.annotation.Aspect;

import org.springframework.stereotype.Component;

@Component

@Aspect

public class MultipleDataSourceAspectAdvice {

    @Around("execution(* com.cnblogs.lzrabbit.*.*(..))")

    public Object doAround(ProceedingJoinPoint jp) throws Throwable {

        if (jp.getTarget() instanceof MySqlMapper) {

            MultipleDataSource.setDataSourceKey("mySqlDataSource");

        } else if (jp.getTarget() instanceof SqlServerMapper) {

            MultipleDataSource.setDataSourceKey("sqlServerDataSource");

        }

        return jp.proceed();

    }

}

配置详解

这里就上面的实现做个简单解释，在我们配置单数据源时可以看到数据源类型使用了org.apache.commons.dbcp.BasicDataSource，而这个代码实现了javax.sql.DataSource接口

配置sqlSessionFactory时org.mybatis.spring.SqlSessionFactoryBean注入参数dataSource类型就是javax.sql.DataSource

实现多数据源的方法就是我们自定义了一个MultipleDataSource，这个类继承自AbstractRoutingDataSource，而AbstractRoutingDataSource继承自AbstractDataSource ，AbstractDataSource 实现了javax.sql.DataSource接口，所以我们的MultipleDataSource也实现了javax.sql.DataSource接口，可以赋值给sqlSessionFactory的dataSource属性

public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {

}

public abstract class AbstractDataSource implements DataSource {

}

再来说下MultipleDataSource的实现原理，MultipleDataSource实现AbstractRoutingDataSource抽象类，然后实现了determineCurrentLookupKey方法，这个方法用于选择具体使用targetDataSources中的哪一个数据源

<bean id="multipleDataSource" class="com.cnblogs.lzrabbit.MultipleDataSource">

        <property name="defaultTargetDataSource" ref="mySqlDataSource"/>

        <property name="targetDataSources">

            <map>

                <entry key="mySqlDataSource" value-ref="mySqlDataSource"/>

                <entry key="sqlServerDataSource" value-ref="sqlServerDataSource"/>

            </map>

        </property>

    </bean>

可以看到Spring配置中multipleDataSource设置了两个属性defaultTargetDataSource和targetDataSources，这两个属性定义在AbstractRoutingDataSource，当MyBatis执行查询时会先选择数据源，选择顺序时现根据determineCurrentLookupKey方法返回的值到targetDataSources中去找，若能找到怎返回对应的数据源，若找不到返回默认的数据源defaultTargetDataSource，具体参考AbstractRoutingDataSource的源码

public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {

    private Map<Object, Object> targetDataSources;

    private Object defaultTargetDataSource;

    /**

     * Retrieve the current target DataSource. Determines the

     * {@link #determineCurrentLookupKey() current lookup key}, performs

     * a lookup in the {@link #setTargetDataSources targetDataSources} map,

     * falls back to the specified

     * {@link #setDefaultTargetDataSource default target DataSource} if necessary.

     * @see #determineCurrentLookupKey()

     */

    protected DataSource determineTargetDataSource() {

        Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");

        Object lookupKey = determineCurrentLookupKey();

        DataSource dataSource = this.resolvedDataSources.get(lookupKey);

        if (dataSource == null && (this.lenientFallback || lookupKey == null)) {

            dataSource = this.resolvedDefaultDataSource;

        }

        if (dataSource == null) {

            throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");

        }

        return dataSource;

    }

    /**

     * Determine the current lookup key. This will typically be

     * implemented to check a thread-bound transaction context.

     * <p>Allows for arbitrary keys. The returned key needs

     * to match the stored lookup key type, as resolved by the

     * {@link #resolveSpecifiedLookupKey} method.

     */

    protected abstract Object determineCurrentLookupKey();

　　

　　.............

}

在动态切换数据源方法时选择了AOP方式实现，这里实现的简单粗暴，具体应用时根据实际需要灵活变通吧

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