JAVA-SSM框架中配置mysql读写分离,动态加载数据源

实现读写分离的两种方法

1、第一种方式是我们最常用的方式，就是定义2个数据库连接，一个是MasterDataSource,另一个是SlaveDataSource。更新数据时我们读取MasterDataSource，查询数据时我们读取SlaveDataSource。

2、第二种方式动态数据源切换，就是在程序运行时，把数据源动态织入到程序中，从而选择读取主库还是从库。主要使用的技术是：Annotation(spring 注解)，spring AOP（面向切面） ，反射。
我采用的方式为第二种，废话不多说上代码吧。

一、DataSourceHandler（数据源的Handler类）

/** * 数据源的Handler类 */public class DataSourceHandler {     // 数据源名称线程池    public static final ThreadLocal<String> holder = new ThreadLocal<String>();    /**     * 在项目启动的时候将配置的读、写数据源加到holder中     */    public static void putDataSource(String datasource) {        System.err.println("putDataSource:....."+datasource);        holder.set(datasource);    }    /**     * 从holer中获取数据源字符串     */    public static String getDataSource() {        return holder.get();    }}

二、ChooseDataSource（获取数据源，用于动态切换数据源）

public  class ChooseDataSource extends AbstractRoutingDataSource {     public static Map<String, List<String>> METHOD_TYPE_MAP = new HashMap<String, List<String>>();     protected Logger logger = LoggerFactory.getLogger(this.getClass());     /**         * 实现父类中的抽象方法，获取数据源名称         * @return         */        protected Object determineCurrentLookupKey() {            logger.info("determineCurrentLookupKey:....."+DataSourceHandler.getDataSource());            return DataSourceHandler.getDataSource();        }        // 设置方法名前缀对应的数据源        public void setMethodType(Map<String, String> map) {            for (String key : map.keySet()) {                List<String> v = new ArrayList<String>();                String[] types = map.get(key).split(",");                for (String type : types) {                    if (StringUtils.isNotBlank(type)) {                        v.add(type);                    }                }                METHOD_TYPE_MAP.put(key, v);            }        }}

三、DataSourceAspect（ 切换数据源(不同方法调用不同数据源)）

/** * 切换数据源(不同方法调用不同数据源) */@Aspect@Component@EnableAspectJAutoProxy(proxyTargetClass = true)public class DataSourceAspect {    protected Logger logger = LoggerFactory.getLogger(this.getClass());     @Pointcut("execution(* com.ssm.dao.DAO.*(..))")        public void aspect() {        }        /**         * 配置前置通知,使用在方法aspect()上注册的切入点         */        @Before("aspect()")        public void before(JoinPoint point) {            String className = point.getTarget().getClass().getName();            String method = point.getSignature().getName();            logger.info("切入具体位置："+className + "." + method + "(" + StringUtils.join(point.getArgs(), ",") + ")");            logger.info("切入类名称："+className);            logger.info("切入类方法名称："+method);            logger.info("方法参数："+StringUtils.join(point.getArgs(), ","));            try {                for (String key : ChooseDataSource.METHOD_TYPE_MAP.keySet()) {                    for (String type : ChooseDataSource.METHOD_TYPE_MAP.get(key)) {                        if (method.startsWith(type)) {                            DataSourceHandler.putDataSource(key);                        }                    }                }              } catch (Exception e) {                e.printStackTrace();            }        }}

四、ApplicationContext-dataSource.xml（Spring数据源配置文件）

<?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:aop="http://www.springframework.org/schema/aop"     xmlns:context="http://www.springframework.org/schema/context"    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/aop                         http://www.springframework.org/schema/aop/spring-aop.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    ">    <!--写连接池 -->    <bean id="writeDataSource" class="com.alibaba.druid.pool.DruidDataSource" destroy-method="close">           <!-- 数据库基本信息配置 -->         <property name="url" value="${url}" />           <property name="username" value="${username}" />           <property name="password" value="${password}" />           <property name="driverClassName" value="${driverClassName}" />           <property name="filters" value="${filters}" />           <!-- 最大并发连接数 -->         <property name="maxActive" value="${maxActive}" />         <!-- 初始化连接数量 -->         <property name="initialSize" value="${initialSize}" />         <!-- 配置获取连接等待超时的时间 -->         <property name="maxWait" value="${maxWait}" />         <!-- 最小空闲连接数 -->         <property name="minIdle" value="${minIdle}" />           <!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 -->         <property name="timeBetweenEvictionRunsMillis" value="${timeBetweenEvictionRunsMillis}" />         <!-- 配置一个连接在池中最小生存的时间，单位是毫秒 -->         <property name="minEvictableIdleTimeMillis" value="${minEvictableIdleTimeMillis}" />           <property name="validationQuery" value="${validationQuery}" />           <property name="testWhileIdle" value="${testWhileIdle}" />           <property name="testOnBorrow" value="${testOnBorrow}" />           <property name="testOnReturn" value="${testOnReturn}" />           <property name="maxOpenPreparedStatements" value="${maxOpenPreparedStatements}" />         <!-- 打开removeAbandoned功能 -->         <property name="removeAbandoned" value="${removeAbandoned}" />         <!-- 1800秒，也就是30分钟 -->         <property name="removeAbandonedTimeout" value="${removeAbandonedTimeout}" />         <!-- 关闭abanded连接时输出错误日志 -->            <property name="logAbandoned" value="${logAbandoned}" />    </bean>      <!--读连接池 -->    <bean id="readDataSource" class="com.alibaba.druid.pool.DruidDataSource" destroy-method="close">          <property name="url" value="${url2}" />           <property name="username" value="${username2}" />           <property name="password" value="${password2}" />           <property name="driverClassName" value="${driverClassName2}" />           <property name="filters" value="${filters2}" />           <property name="maxActive" value="${maxActive2}" />         <property name="initialSize" value="${initialSize2}" />         <property name="maxWait" value="${maxWait2}" />         <property name="minIdle" value="${minIdle2}" />           <property name="timeBetweenEvictionRunsMillis" value="${timeBetweenEvictionRunsMillis2}" />         <property name="minEvictableIdleTimeMillis" value="${minEvictableIdleTimeMillis2}" />           <property name="validationQuery" value="${validationQuery2}" />           <property name="testWhileIdle" value="${testWhileIdle2}" />           <property name="testOnBorrow" value="${testOnBorrow2}" />           <property name="testOnReturn" value="${testOnReturn2}" />           <property name="maxOpenPreparedStatements" value="${maxOpenPreparedStatements2}" />         <property name="removeAbandoned" value="${removeAbandoned2}" />         <property name="removeAbandonedTimeout" value="${removeAbandonedTimeout2}" />         <property name="logAbandoned" value="${logAbandoned2}" />    </bean>    <!-- 配置动态分配的读写 数据源 -->    <bean id="dataSource" class="com.ssm.aspect.ChooseDataSource" lazy-init="true">        <property name="targetDataSources">            <map key-type="java.lang.String" value-type="javax.sql.DataSource">                <!-- write -->                <entry key="write" value-ref="writeDataSource"/>                <!-- read -->                <entry key="read" value-ref="readDataSource"/>            </map>        </property>        <property name="defaultTargetDataSource" ref="writeDataSource"/>        <property name="methodType">            <map key-type="java.lang.String">                <!-- read -->                <entry key="read" value=",findForObject,findForList,findForMap,"/>                <!-- write -->                <entry key="write" value=",save,batchSave,update,batchUpdate,delete,"/>            </map>        </property>    </bean>    <!-- sql会话模版 -->    <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate" scope="prototype">        <constructor-arg ref="sqlSessionFactory" />    </bean>    <!-- 配置mybatis -->    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">        <property name="dataSource" ref="dataSource" />        <property name="configLocation" value="classpath:mybatis1/mybatis-config.xml"></property>        <!-- mapper扫描 -->        <property name="mapperLocations" value="classpath:mybatis1/*/*.xml"></property>    </bean>    <!-- 事物处理 -->    <aop:config>        <aop:pointcut id="pc" expression="execution(* com.ssm.service..*(..))" />        <aop:advisor pointcut-ref="pc" advice-ref="txAdvice" />    </aop:config>    <tx:advice id="txAdvice" transaction-manager="transactionManager">        <tx:attributes>            <tx:method name="delete*" propagation="REQUIRED" read-only="false"                        rollback-for="java.lang.Exception"/>            <tx:method name="insert*" propagation="REQUIRED" read-only="false"                        rollback-for="java.lang.Exception" />            <tx:method name="update*" propagation="REQUIRED" read-only="false"                        rollback-for="java.lang.Exception" />            <tx:method name="save*" propagation="REQUIRED" read-only="false"                        rollback-for="java.lang.Exception" />            <tx:method name="batch*" propagation="REQUIRED" read-only="false"                        rollback-for="java.lang.Exception" />                  </tx:attributes>    </tx:advice>    <bean name="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">           <property name="dataSource" ref="dataSource"></property>    </bean></beans>