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>