一、jdbc.properties 文件

兩個數據庫，這裏使用的postgresql 數據庫

jdbc.driver=org.postgresql.Driver
jdbc.url=jdbc:postgresql://localhost:5432/aaa
jdbc.username=
jdbc.password=
c3p0.maxPoolSize=5
c3p0.minPoolSize=2
c3p0.autoCommitOnClose=false
c3p0.checkoutTimeout=10000
c3p0.maxIdleTime=60
c3p0.idleConnectionTestPeriod=60
c3p0.numHelperThreads=3
c3p0.acquireRetryAttempts=2
jdbc2.driver=org.postgresql.Driver
jdbc2.url=jdbc:postgresql://lcoalhost:5432/bbb
jdbc2.username=
jdbc2.password=
c3p02.maxPoolSize=5
c3p02.minPoolSize=2
c3p02.autoCommitOnClose=false
c3p02.checkoutTimeout=10000
c3p02.maxIdleTime=60
c3p02.idleConnectionTestPeriod=60
c3p02.numHelperThreads=3
c3p02.acquireRetryAttempts=2

二、寫 DynamicDataSource 類

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


public class DynamicDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        // 從自定義的位置獲取數據源標識
        return DynamicDataSourceHolder.getDataSource();
    }
}

三、寫 DynamicDataSourceHolder 類


public class DynamicDataSourceHolder {  /**
 * 注意：數據源標識保存在線程變量中，避免多線程操作數據源時互相干擾
 */
private static final ThreadLocal<String> THREAD_DATA_SOURCE = new ThreadLocal<String>();

    public static String getDataSource() {
        return THREAD_DATA_SOURCE.get();
    }

    public static void setDataSource(String dataSource) {
        THREAD_DATA_SOURCE.set(dataSource);
    }

    public static void clearDataSource() {
        THREAD_DATA_SOURCE.remove();
    }
}

四、修改 spring-mybatis.xml 文件

1.定義了兩個數據源

<!-- 數據庫連接池 -->
    <bean id="dataSource1" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="jdbcUrl" value="${jdbc.url}"/>
        <property name="user" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="maxPoolSize" value="${c3p0.maxPoolSize}"/>
        <property name="minPoolSize" value="${c3p0.minPoolSize}"/>
        <property name="autoCommitOnClose" value="${c3p0.autoCommitOnClose}"/>
        <property name="checkoutTimeout" value="${c3p0.checkoutTimeout}"/>
        <property name="acquireRetryAttempts" value="${c3p0.acquireRetryAttempts}"/>
        <property name="maxIdleTime" value="${c3p0.maxIdleTime}"/>
        <property name="idleConnectionTestPeriod" value="${c3p0.idleConnectionTestPeriod}"/>
        <property name="numHelperThreads" value="${c3p0.numHelperThreads}"/>
    </bean>
    <!-- 數據庫連接池 -->
    <bean id="dataSource2" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc2.driver}"/>
        <property name="jdbcUrl" value="${jdbc2.url}"/>
        <property name="user" value="${jdbc2.username}"/>
        <property name="password" value="${jdbc2.password}"/>
        <property name="maxPoolSize" value="${c3p02.maxPoolSize}"/>
        <property name="minPoolSize" value="${c3p02.minPoolSize}"/>
        <property name="autoCommitOnClose" value="${c3p02.autoCommitOnClose}"/>
        <property name="checkoutTimeout" value="${c3p02.checkoutTimeout}"/>
        <property name="acquireRetryAttempts" value="${c3p02.acquireRetryAttempts}"/>
        <property name="maxIdleTime" value="${c3p02.maxIdleTime}"/>
        <property name="idleConnectionTestPeriod" value="${c3p02.idleConnectionTestPeriod}"/>
        <property name="numHelperThreads" value="${c3p02.numHelperThreads}"/>
    </bean>

2. 使用 DynamicDataSource 動態切換數據源

 <bean id="dataSource" class="com.cmbird.Util.DynamicDataSource">
        <property name="targetDataSources">
            <map key-type="java.lang.String">
                <entry key="dataSource1" value-ref="dataSource1"/>
                <entry key="dataSource2" value-ref="dataSource2"/>
            </map>
        </property>
        <!--默認數據源-->
        <property name="defaultTargetDataSource" ref="dataSource1"/>
    </bean>

五、測試

   @Test
    public void selectByPrimaryKey() throws Exception {
        DynamicDataSourceHolder.setDataSource("dataSource2");
        System.out.println(iypzdDao.selectYpzdBB());
        DynamicDataSourceHolder.setDataSource("dataSource1");
        System.out.println(iMapDao.selectMap(true));
    }

會發現已經可以自定義切換了，但還是感覺有些麻煩，這時就想到了用spring 自帶的AOP 和自定義註解的思想.

六、自定義註解

1.新建 DataSource 註解接口類

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ ElementType.TYPE,ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
public @interface DataSource {
    String value();
}

2.寫切面類

import java.lang.reflect.Method;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.reflect.MethodSignature;

public class DataSourceAspect { /**
 * 攔截目標方法，獲取由@DataSource指定的數據源標識，設置到線程存儲中以便切換數據源
 *
 * @param point
 * @throws Exception
 */
public void intercept(JoinPoint point) throws Exception {
    Class<?> target = point.getTarget().getClass();
    MethodSignature signature = (MethodSignature) point.getSignature();
    // 默認使用目標類型的註解，如果沒有則使用其實現接口的註解
    for (Class<?> clazz : target.getInterfaces()) {
        resolveDataSource(clazz, signature.getMethod());
    }
    resolveDataSource(target, signature.getMethod());
}

    /**
     * 提取目標對象方法註解和類型註解中的數據源標識
     *
     * @param clazz
     * @param method
     */
    private void resolveDataSource(Class<?> clazz, Method method) {
        try {
            Class<?>[] types = method.getParameterTypes();
            // 默認使用類型註解
            if (clazz.isAnnotationPresent(DataSource.class)) {
                DataSource source = clazz.getAnnotation(DataSource.class);
                DynamicDataSourceHolder.setDataSource(source.value());
            }
            // 方法註解可以覆蓋類型註解
            Method m = clazz.getMethod(method.getName(), types);
            if (m != null && m.isAnnotationPresent(DataSource.class)) {
                DataSource source = m.getAnnotation(DataSource.class);
                DynamicDataSourceHolder.setDataSource(source.value());
            }
        } catch (Exception e) {
            System.out.println(clazz + ":" + e.getMessage());
        }
    }
}

3.基於xml 寫 aop(修改spring-mybatis.xml）

    <bean id="dataSourceAspect" class="com.cmbird.Util.DataSourceAspect" />
    <aop:config>
        <aop:aspect ref="dataSourceAspect">
            <!-- 攔截所有service方法 -->
            <aop:pointcut id="dataSourcePointcut" expression="execution(* com.zzz.dao..*.*(..))" />
            <aop:before pointcut-ref="dataSourcePointcut" method="intercept" />
        </aop:aspect>
    </aop:config>

4.大工告成

我寫的這個是在每個dao的接口上添加一個註解，比如

@DataSource("dataSource1")
public interface INewsDao {
    /**
     * 刪除數據
     * @param id
     */
    public void deleteNews(long id);

    /**
     * 更新修改數據
     * @param news
     */
    public void updateNews(News news);

    /**
     * 查詢數據
     * @param pageInfo
     */
    public List<News> selectPageNews(PageInfo pageInfo);

    /**
     * 查詢總數量
     */
    public int selectNewsCount();

    /**
     * 新增數據
     * @param news
     */
    public  void addNews(String news);


    public List<News> selectAllNews();
}

就可以使用了.

七、貼一下完整的 spring-mybatis.xml

<?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:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
      http://www.springframework.org/schema/beans/spring-beans.xsd
      http://www.springframework.org/schema/context
      http://www.springframework.org/schema/context/spring-context.xsd
      http://www.springframework.org/schema/tx
      http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">

    <!-- 掃描service包下所有使用註解的類型 -->
    <context:component-scan base-package="com.cmbird.service"/>

    <!-- 配置數據庫相關參數properties的屬性：${url} -->
    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!-- 數據庫連接池 -->
    <bean id="dataSource1" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="jdbcUrl" value="${jdbc.url}"/>
        <property name="user" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="maxPoolSize" value="${c3p0.maxPoolSize}"/>
        <property name="minPoolSize" value="${c3p0.minPoolSize}"/>
        <property name="autoCommitOnClose" value="${c3p0.autoCommitOnClose}"/>
        <property name="checkoutTimeout" value="${c3p0.checkoutTimeout}"/>
        <property name="acquireRetryAttempts" value="${c3p0.acquireRetryAttempts}"/>
        <property name="maxIdleTime" value="${c3p0.maxIdleTime}"/>
        <property name="idleConnectionTestPeriod" value="${c3p0.idleConnectionTestPeriod}"/>
        <property name="numHelperThreads" value="${c3p0.numHelperThreads}"/>
    </bean>
    <!-- 數據庫連接池 -->
    <bean id="dataSource2" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc2.driver}"/>
        <property name="jdbcUrl" value="${jdbc2.url}"/>
        <property name="user" value="${jdbc2.username}"/>
        <property name="password" value="${jdbc2.password}"/>
        <property name="maxPoolSize" value="${c3p02.maxPoolSize}"/>
        <property name="minPoolSize" value="${c3p02.minPoolSize}"/>
        <property name="autoCommitOnClose" value="${c3p02.autoCommitOnClose}"/>
        <property name="checkoutTimeout" value="${c3p02.checkoutTimeout}"/>
        <property name="acquireRetryAttempts" value="${c3p02.acquireRetryAttempts}"/>
        <property name="maxIdleTime" value="${c3p02.maxIdleTime}"/>
        <property name="idleConnectionTestPeriod" value="${c3p02.idleConnectionTestPeriod}"/>
        <property name="numHelperThreads" value="${c3p02.numHelperThreads}"/>
    </bean>

    <bean id="dataSource" class="com.cmbird.Util.DynamicDataSource">
        <property name="targetDataSources">
            <map key-type="java.lang.String">
                <entry key="dataSource1" value-ref="dataSource1"/>
                <entry key="dataSource2" value-ref="dataSource2"/>
            </map>
        </property>
        <!--默認數據源-->
        <property name="defaultTargetDataSource" ref="dataSource1"/>
    </bean>

    <bean id="dataSourceAspect" class="com.cmbird.Util.DataSourceAspect" />
    <aop:config>
        <aop:aspect ref="dataSourceAspect">
            <!-- 攔截所有service方法 -->
            <aop:pointcut id="dataSourcePointcut" expression="execution(* com.cmbird.dao..*.*(..))" />
            <aop:before pointcut-ref="dataSourcePointcut" method="intercept" />
        </aop:aspect>
    </aop:config>

    <!-- 配置SqlSessionFactory對象 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 注入數據庫連接池 -->
        <property name="dataSource" ref="dataSource"/>
        <!-- 掃描model包 使用別名 -->
        <property name="typeAliasesPackage" value="com.cmbird.model"/>
        <!-- 掃描sql配置文件:mapper需要的xml文件 -->
        <property name="mapperLocations" value="classpath:mapper/**/*.xml"/>
    </bean>

    <!-- 配置掃描Dao接口包，動態實現Dao接口，注入到spring容器中 -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 注入sqlSessionFactory -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <!-- 給出需要掃描Dao接口包 -->
        <property name="basePackage" value="com.cmbird.dao"/>
    </bean>

    <!-- 配置事務管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <!-- 注入數據庫連接池 -->
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <!-- 配置基於註解的聲明式事務 -->
    <tx:annotation-driven transaction-manager="transactionManager"/>

</beans>

ps:我碰到了這個問題，找了很多資料，也試了很多次，確沒有一個能用的。然後我又自己研究了一下，感覺還可以，貼出來以免忘記.

SSM 動態切換數據源

一、jdbc.properties 文件

二、寫 DynamicDataSource 類

三、寫 DynamicDataSourceHolder 類

四、修改 spring-mybatis.xml 文件

1.定義了兩個數據源

2. 使用 DynamicDataSource 動態切換數據源

五、測試

六、自定義註解

1.新建 DataSource 註解接口類

2.寫切面類

3.基於xml 寫 aop(修改spring-mybatis.xml）

4.大工告成

七、貼一下完整的 spring-mybatis.xml

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SSM 動態切換數據源

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