Spring实现数据库读写分离/spring事务配置解释(Annotation/Spring AOP/Reflection)
项目开发中读写的频率差距很大，所以实现读写分离：主库(master)中非实时读取的查询交给负载均衡的从库(slave)，查询cpu的消耗和写入的io延时，保证DB系统的健壮性。
最终问题，分布式事务的线索。最后附源码[springmvc+spring+mybatis+MySQL]：
注：注释和部分代码省略。
①：AbstractRoutingDataSource这个数据源路由类是spring2.0以后增加的，AbstractRoutingDataSource的定义：
/* @since 2.0.1*/
public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {……}
通过实现determineCurrentLookupKey()抽象方法可以实现读写数据源的切换。
②：AbstractRoutingDataSource继承了AbstractDataSource，而AbstractDataSource是DataSource的子类。DataSource是javax.sql的数据源接口，定义：
public interface DataSource extends CommonDataSource,Wrapper {
Connection getConnection() throws SQLException;
Connection getConnection(String username, String password) throws SQLException;
}
DataSource数据源接口定义了2个方法，都是获取数据库连接的。
③：AbstractRoutingDataSource这个数据源路由类对获取连接的实现：
public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {
private Map<Object, DataSource> resolvedDataSources;
private Object defaultTargetDataSource;
private Map<Object, Object> targetDataSources;
@Override
public Connection getConnection() throws SQLException {
return determineTargetDataSource().getConnection();
}
@Override
public Connection getConnection(String username, String password) throws SQLException {
return determineTargetDataSource().getConnection(username, password);
}
protected abstract Object determineCurrentLookupKey();
}
通过自己定义的determineTargetDataSource()方法获取到数据连接connection。
④：determineTargetDataSource的定义：
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;
}
determineCurrentLookupKey方法返回lookupKey,resolvedDataSources方法就是根据lookupKey从Map中获得数据源。从③看出resolvedDataSources集合属性和determineCurrentLookupKey()抽象方法定义。
⑤：我们自己定义类继承路由类去实现determineCurrentLookupKey()方法，然后自己来切换字符串告诉this.resolvedDataSources.get(lookupKey);方法这个lookupKey是谁？(也就是这个字符所对应的数据源的key(请看mybatis-context.xml配置40行注入defaultTargetDataSource和targetDataSources的值,通过‘lookupKey’字符串切换，spring<span style="font-family: Arial, Helvetica, sans-serif;">注入的数据源对象))。</span>1：通过注解在dao方法上注解，此方法开启那个数据源：
package com.common.readwriteseparate;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface DataSource {
String value();
}2：自己定义类继承路由类去实现determineCurrentLookupKey()方法：
package com.common.readwriteseparate;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
public class DynamicDataSource extends AbstractRoutingDataSource{
@Override
protected Object determineCurrentLookupKey() {
String dataSouceKey = DynamicDataSourceHolder.getDataSouce();
return dataSouceKey;
}
}多线程辅助类：
package com.common.readwriteseparate;
public class DynamicDataSourceHolder {
public static final ThreadLocal<String> holder = new ThreadLocal<String>();
public static void putDataSource(String name) {
holder.set(name);
}
public static String getDataSouce() {
return holder.get();
}
}
在DynamicDataSource的定义知道，返回的是DynamicDataSourceHolder.getDataSouce()值，我们需要在程序运行时调用DynamicDataSourceHolder.putDataSource()方法，对dataSouceKey数据源key赋值。
package com.common.readwriteseparate;
import java.lang.reflect.Method;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class DataSourceAspect {
//log
private static final Logger LOG = LoggerFactory.getLogger(DataSourceAspect.class);
public void before(JoinPoint point) {
Object target = point.getTarget();
String method = point.getSignature().getName();
Class<?>[] classz = target.getClass().getInterfaces();
Class<?>[] parameterTypes = ((MethodSignature) point.getSignature()).getMethod().getParameterTypes();
try {
Method methodRefRes = classz[0].getMethod(method, parameterTypes);
if (methodRefRes != null && methodRefRes.isAnnotationPresent(DataSource.class)) {
DataSource data = methodRefRes.getAnnotation(DataSource.class);
DynamicDataSourceHolder.putDataSource(data.value());
LOG.info("\n************************************************\n" + "\t~~~DB:: " + data.value() + "\n************************************************");
}
} catch (Exception e) {
LOG.error("数据源失败切面获取异常:" + e.getMessage(), e);
}
}
}
5：先看看配置：
①spring的配置(spring-context.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:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">
<!-- 使用annotation 自动注册bean,并检查@Required,@Autowired的属性已被注入 -->
<context:component-scan base-package="com.user.service,com.user.dao,com.user.bean,com.user.xml" />
<!-- 引入属性配置文件 -->
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location" value="classpath:database.properties" />
</bean>
<!--或 <context:property-placeholder location="classpath*:*.properties" /> -->
</beans> ②：mybatis-context.xml的配置：
<?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:mvc="http://www.springframework.org/schema/mvc"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-4.0.xsd" default-lazy-init="true">
<description>MyBatis的数据库持久层配置/配置主-从数据源</description>
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<!-- 自动扫描entity目录, 省掉Configuration.xml里的手工配置 -->
<property name="mapperLocations" value="classpath*:com/user/xml/*.xml" />
<property name="configLocation" value="classpath:mybatis-config.xml"></property>
</bean>
<!-- 扫描dao -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.user.dao" />
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
</bean>
<!-- 配置数据库注解aop -->
<aop:aspectj-autoproxy />
<bean id="dataSourceAspect" class="com.common.readwriteseparate.DataSourceAspect" />
<aop:config>
<aop:aspect id="c" ref="dataSourceAspect">
<aop:pointcut id="tx" expression="execution(* com.user.dao.*.*(..))" />
<aop:before pointcut-ref="tx" method="before" />
</aop:aspect>
</aop:config>
<!-- 主-从数据源路由 -->
<bean id="dataSource" class="com.common.readwriteseparate.DynamicDataSource">
<property name="targetDataSources">
<map key-type="java.lang.String">
<!-- write -->
<entry key="master" value-ref="masterDataSource"/>
<!-- read -->
<entry key="slave" value-ref="slaveDataSource"/>
</map>
</property>
<property name="defaultTargetDataSource" ref="masterDataSource"/>
</bean>
</beans>③：mybatis-config.xml：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<typeAliases>
<package name="com.user.bean"/>
</typeAliases>
</configuration> ④：database.properties：
#mysql-Used to verify the effectiveness of the database connection validationQuery=SELECT 1 jdbc.initialSize=5 jdbc.maxActive=20 jdbc.maxWait=60000 jdbc.poolPreparedStatements=false jdbc.poolMaximumIdleConnections=0 jdbc.driverClassName=org.gjt.mm.mysql.Driver #1.tms business. 2.The db level optimization,data concurrency,desirable. master.jdbc.url=jdbc:mysql://your ip:3306/master?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull slave.jdbc.url=jdbc:mysql://your ip:3306/slave?useUnicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull jdbc.username=username jdbc.password=password⑤：数据源配置：datasource-context.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:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-4.0.xsd" default-lazy-init="true">
<description>配置主-从数据源</description>
<!-- 配置数据源-Master -->
<bean name="masterDataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
<property name="driverClassName" value="${jdbc.driverClassName}" />
<property name="url" value="${master.jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<!-- 初始化连接大小 -->
<property name="initialSize" value="0" />
<!-- 连接池最大使用连接数量 -->
<property name="maxActive" value="20" />
<!-- 连接池最大空闲 error:maxIdle is deprecated -->
<!-- <property name="maxIdle" value="20" /> -->
<!-- 连接池最小空闲 -->
<property name="minIdle" value="0" />
<!-- 获取连接最大等待时间 -->
<property name="maxWait" value="60000" />
<!-- <property name="poolPreparedStatements" value="true" /> <property name="maxPoolPreparedStatementPerConnectionSize" value="33" /> -->
<property name="validationQuery" value="${validationQuery}" />
<property name="testOnBorrow" value="false" />
<property name="testOnReturn" value="false" />
<property name="testWhileIdle" value="true" />
<!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 -->
<property name="timeBetweenEvictionRunsMillis" value="60000" />
<!-- 配置一个连接在池中最小生存的时间，单位是毫秒 -->
<property name="minEvictableIdleTimeMillis" value="25200000" />
<!-- 打开removeAbandoned功能 -->
<property name="removeAbandoned" value="true" />
<!-- 1800秒，也就是30分钟 -->
<property name="removeAbandonedTimeout" value="1800" />
<!-- 关闭abanded连接时输出错误日志 -->
<property name="logAbandoned" value="true" />
<!-- 监控数据库 -->
<!-- <property name="filters" value="stat" /> -->
<property name="filters" value="mergeStat" />
</bean>
<!-- 配置数据源-Slave -->
<bean name="slaveDataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
<property name="driverClassName" value="${jdbc.driverClassName}" />
<property name="url" value="${slave.jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
<!-- 初始化连接大小 -->
<property name="initialSize" value="0" />
<!-- 连接池最大使用连接数量 -->
<property name="maxActive" value="20" />
<!-- 连接池最大空闲 error:maxIdle is deprecated -->
<!-- <property name="maxIdle" value="20" /> -->
<!-- 连接池最小空闲 -->
<property name="minIdle" value="0" />
<!-- 获取连接最大等待时间 -->
<property name="maxWait" value="60000" />
<!-- <property name="poolPreparedStatements" value="true" /> <property name="maxPoolPreparedStatementPerConnectionSize" value="33" /> -->
<property name="validationQuery" value="${validationQuery}" />
<property name="testOnBorrow" value="false" />
<property name="testOnReturn" value="false" />
<property name="testWhileIdle" value="true" />
<!-- 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="60000" />
<!-- 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="25200000" />
<!-- 打开removeAbandoned功能 -->
<property name="removeAbandoned" value="true" />
<!-- 1800秒，也就是30分钟 -->
<property name="removeAbandonedTimeout" value="1800" />
<!-- 关闭abanded连接时输出错误日志 -->
<property name="logAbandoned" value="true" />
<!-- 监控数据库 -->
<!-- <property name="filters" value="stat" /> -->
<property name="filters" value="mergeStat" />
</bean>
</beans>⑥transaction-context.xml事务配置：
<?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:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd" default-lazy-init="true"> <description>配置事物</description> <!-- 注解方式配置事物 --> <tx:annotation-driven transaction-manager="transactionManager" /> <!-- 配置事务管理器 --> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource" /> </bean> <aop:config> <aop:pointcut expression="(execution(* com.user.service.*.* (..)))" id="pointcut" /> <aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" /> </aop:config> <!-- 事务控制 --> <tx:advice id="txAdvice" transaction-manager="transactionManager"> <tx:attributes> <tx:method name="load*" read-only="true" /> <tx:method name="get*" read-only="true" /> <tx:method name="create*" propagation="REQUIRED" rollback-for="java.lang.Exception" /> <tx:method name="save*" propagation="REQUIRED" rollback-for="java.lang.Exception" /> <tx:method name="update*" propagation="REQUIRED" rollback-for="java.lang.Exception" /> <tx:method name="insert*" propagation="REQUIRED" rollback-for="java.lang.Exception" /> <tx:method name="delete*" propagation="REQUIRED" rollback-for="java.lang.Exception" /> <tx:method name="schedule*" propagation="REQUIRED" rollback-for="java.lang.Exception" /> <tx:method name="do*" propagation="REQUIRED" rollback-for="java.lang.Exception" /> <!-- 一个事务涉及一个数据源不能在事务内部去切换数据源成功，所以对多数据源的方法暂不开启事务~分布式事务 --> <!-- <tx:method name="crud*" propagation="REQUIRED" rollback-for="java.lang.Exception" /> --> <!-- <tx:method name="*" /> --> </tx:attributes> </tx:advice> </beans>⑦：log4j.properties日志配置:
# Set root category priority to INFO and its only appender to CONSOLE.
log4j.rootLogger=info, STDOUT, FILEOUT
# CONSOLE is set to be a ConsoleAppender using a PatternLayout.
log4j.appender.STDOUT=org.apache.log4j.ConsoleAppender
log4j.appender.STDOUT.encoding=UTF-8
log4j.appender.STDOUT.layout=org.apache.log4j.PatternLayout
log4j.appender.STDOUT.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] - [ %p ] %m %n
# FILEOUT is set to be a File appender using a PatternLayout.
log4j.appender.FILEOUT=org.apache.log4j.RollingFileAppender
#tomcat1
#log4j.appender.FILEOUT.File=/home/logs/timespacexstar1/timespacexstar.log
#tomcat2
log4j.appender.FILEOUT.File=/home/logs/mydemoweb/mydemoweb.log
log4j.appender.FILEOUT.MaxFileSize=5MB
log4j.appender.FILEOUT.MaxBackupIndex=10
log4j.appender.FILEOUT.encoding=UTF-8
log4j.appender.FILEOUT.layout=org.apache.log4j.PatternLayout
log4j.appender.FILEOUT.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] - [ %p ] %m %n
# SQL
log4j.logger.java.sql.ResultSet=debug
log4j.logger.org.apache=debug
log4j.logger.java.sql.Connection=debug
log4j.logger.java.sql.Statement=debug
log4j.logger.java.sql.PreparedStatement=debug6：代码实现：
①：dao层：
package com.user.dao;
import com.common.readwriteseparate.DataSource;
import com.user.bean.Member;
public interface MemberMapper {
@DataSource("master")
int deleteByPrimaryKey(Integer id);
@DataSource("master")
int insert(Member record);
@DataSource("master")
int insertSelective(Member record);
@DataSource("master")
int updateByPrimaryKeySelective(Member record);
@DataSource("master")
int updateByPrimaryKey(Member record);
@DataSource("slave")
Member selectByPrimaryKey(Integer id);
}②：业务层代码：
package com.user.service;
import com.user.bean.Member;
public interface MemberService {
Member crudMember(Member member);
}
实现：
package com.user.service.impl;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.interceptor.TransactionAspectSupport;
import com.user.bean.Member;
import com.user.dao.MemberMapper;
import com.user.service.MemberService;
@Service("memberService")
public class MemberServiceImpl implements MemberService {
//log
private static final Logger LOG = LoggerFactory.getLogger(MemberServiceImpl.class);
@Autowired
private MemberMapper memeberDao;
@Override
public Member crudMember(Member member) {
Member resMember = null;
try {
resMember = memeberDao.selectByPrimaryKey(member.getId());
LOG.info(member.getId() + "查询成功~");
memeberDao.insert(member);
LOG.info(member.getUsername() + "注册成功~");
} catch (Exception e) {
LOG.error("用户id："+member.getId()+"保存和查询失败~~~" + e.getMessage(), e);
TransactionAspectSupport.currentTransactionStatus().setRollbackOnly();
}
return resMember;
}
}③：master数据库没有id为2的member注册，但slave中有一个用户，先查询从库用户，再插入主库这个member，不涉及业务仅对分库测试：
junit测试代码：
package com.user.test;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import com.common.definition.DictionaryDefinition;
import com.user.bean.Member;
import com.user.service.MemberService;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:spring-context.xml","classpath:datasource-context.xml",
"classpath:mybatis-context.xml","classpath:transaction-context.xml"})
public class UserTest {
//log
private static final Logger LOG = LoggerFactory.getLogger(UserTest.class);
@Autowired
private MemberService memberService;
/**
* 主从分离测试，非支持事务
* */
@Test
public void crudTraM(){
Member member = new Member();
member.setId(2);
member.setUsername("Tony5");
member.setPassword("12345678");
member.setStatus(DictionaryDefinition.LOGIN_NORMAL);
Member member1 = memberService.crudMember(member);
if(member1 != null){
LOG.info("结果~~：" + member1.getUsername());
}else{
LOG.info("主从事物回滚测试失败数据为空");
}
}
}
效果：master插入前：
后：
slave前后不变：
junit代码测试结果log：
2016-04-11 18:48:32 [ main:2195 ] - [ INFO ] ************************************************ ~~~DB:: slave ************************************************ 2016-04-11 18:48:32 [ main:2879 ] - [ INFO ] 2查询成功~ 2016-04-11 18:48:32 [ main:2880 ] - [ INFO ] ************************************************ ~~~DB:: master ************************************************ 2016-04-11 18:48:32 [ main:2977 ] - [ INFO ] Tony5注册成功~ 2016-04-11 18:48:32 [ main:2977 ] - [ INFO ] 结果~~：kekeai上边完成了在service层同一方法中数据源的切换，但这个方法必须不支持事务，不然切换失败！！！
A:spring事务的默然配置：
<tx:method name="*" />
默认意义：
①：事务传播设置是 REQUIRED
②：隔离级别是数据库 DEFAULT
③：事务是支持 读/写
④：事务超时默认是依赖于事务系统的，或者事务超时没有被支持。
⑤：任何 RuntimeException 将触发事务回滚，但是任何 checked Exception 将不触发事务回滚
<tx:method/> 有关事务自定义的设置：
源代码：Spring实现数据库读写分离
数据库sql：db_rw_separate.sql