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>