Spring实现动态数据源切换的方法总结

public abstract class AbstractRoutingDataSource extends AbstractDataSource 
implements InitializingBean{
    @Nullable
    private Map<Object, Object> targetDataSources;
    @Nullable
    private Object defaultTargetDataSource;
    @Override
    public Connection getConnection() throws SQLException {
        return determineTargetDataSource().getConnection();
    }
    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;
    }
    @Override
    public void afterPropertiesSet() {
        if (this.targetDataSources == null) {
            throw new IllegalArgumentException("Property 'targetDataSources' is required");
        }
        this.resolvedDataSources = new HashMap<>(this.targetDataSources.size());
        this.targetDataSources.forEach((key, value) -> {
            Object lookupKey = resolveSpecifiedLookupKey(key);
            DataSource dataSource = resolveSpecifiedDataSource(value);
            this.resolvedDataSources.put(lookupKey, dataSource);
        });
        if (this.defaultTargetDataSource != null) {
            this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);
        }
    }

<?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:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
<!-- clickhouse数据源   -->
    <bean id="dataSourceClickhousePinpin" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close" lazy-init="true">
        <property name="url" value="${clickhouse.jdbc.pinpin.url}" />
    </bean>
    <bean id="singleSessionFactoryPinpin" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- ref直接指向 数据源dataSourceClickhousePinpin  -->
<property name="dataSource" ref="dataSourceClickhousePinpin" />
    </bean>
</beans>

<?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:tx="http://www.springframework.org/schema/tx"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
<!-- clickhouse数据源 1  -->
    <bean id="dataSourceClickhousePinpin" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close" lazy-init="true">
        <property name="url" value="${clickhouse.jdbc.pinpin.url}" />
    </bean>
<!-- clickhouse数据源 2  -->
    <bean id="dataSourceClickhouseOtherPinpin" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close" lazy-init="true">
        <property name="url" value="${clickhouse.jdbc.other.url}" />
    </bean>
 <!-- 新增配置 封装注册的两个数据源到multiDataSourcePinpin里 -->
 <!-- 对应的key分别是 defaultTargetDataSource和targetDataSources-->
    <bean id="multiDataSourcePinpin" class="com.zhongyouex.bigdata.common.aop.MultiDataSource">
      <!-- 默认使用的数据源-->
<property name="defaultTargetDataSource" ref="dataSourceClickhousePinpin"></property>
        <!-- 存储其他数据源，对应源码中的targetDataSources -->
<property name="targetDataSources">
            <!-- 该map即为源码中的resolvedDataSources-->
            <map>
                <!-- dataSourceClickhouseOther 即为要切换的数据源对应的key -->
<entry key="dataSourceClickhouseOther" value-ref="dataSourceClickhouseOtherPinpin"></entry>
            </map>
        </property>
    </bean>
    <bean id="singleSessionFactoryPinpin" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- ref指向封装后的数据源multiDataSourcePinpin  -->
<property name="dataSource" ref="multiDataSourcePinpin" />
    </bean>
</beans>

package com.zhongyouex.bigdata.common.aop;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
/**
 * @author: cuizihua
 * @description: 动态数据源
 * @date: 2021/9/7 20:24
 * @return
 */
public class MultiDataSource extends AbstractRoutingDataSource {
    /* 存储数据源的key值，InheritableThreadLocal用来保证父子线程都能拿到值。
     */
    private static final ThreadLocal<String> dataSourceKey = new InheritableThreadLocal<String>();
    /**
     * 设置dataSourceKey的值
     *
     * @param dataSource
     */
    public static void setDataSourceKey(String dataSource) {
        dataSourceKey.set(dataSource);
    }
    /**
     * 清除dataSourceKey的值
     */
    public static void toDefault() {
        dataSourceKey.remove();
    }
    /**
     * 返回当前dataSourceKey的值
     */
    @Override
    protected Object determineCurrentLookupKey() {
        return dataSourceKey.get();
    }
}

package com.zhongyouex.bigdata.common.aop;
import com.zhongyouex.bigdata.common.util.LoadUtil;
import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.reflect.MethodSignature;
import java.lang.reflect.Method;
/**
 * 方法拦截  粒度在mapper上(对应的sql所属xml)
 * @author cuizihua
 * @desc 切换数据源
 * @create 2021-09-03 16:29
 **/
@Slf4j
public class MultiDataSourceInterceptor {
//动态数据源对应的key
    private final String otherDataSource = "dataSourceClickhouseOther";
    public void beforeOpt(JoinPoint mi) {
//默认使用默认数据源
        MultiDataSource.toDefault();
        //获取执行该方法的信息
        MethodSignature signature = (MethodSignature) mi.getSignature();
        Method method = signature.getMethod();
        String namespace = method.getDeclaringClass().getName();
//本项目命名空间统一的规范为xxx.xxx.xxxMapper
        namespace = namespace.substring(namespace.lastIndexOf(".") + 1);
//这里在配置文件配置的属性为xxxMapper.ck.switch=1 or 0  1表示切换
        String isOtherDataSource = LoadUtil.loadByKey(namespace, "ck.switch");
        if ("1".equalsIgnoreCase(isOtherDataSource)) {
            MultiDataSource.setDataSourceKey(otherDataSource);
            String methodName = method.getName();
        }
    }
}

<!--动态数据源-->
<bean id="multiDataSourceInterceptor" class="com.zhongyouex.bigdata.common.aop.MultiDataSourceInterceptor" ></bean>
<!--将自定义拦截器注入到spring中-->
<aop:config proxy-target-class="true" expose-proxy="true">
    <aop:aspect ref="multiDataSourceInterceptor">
        <!--切入点,也就是你要监控哪些类下的方法，这里写的是DAO层的目录，表达式需要保证只扫描dao层-->
        <aop:pointcut id="multiDataSourcePointcut" expression="execution(*  com.zhongyouex.bigdata.clickhouse..*.*(..)) "/>
        <!--在该切入点使用自定义拦截器-->
        <aop:before method="beforeOpt" pointcut-ref="multiDataSourcePointcut" />
    </aop:aspect>
</aop:config>