利用AbstractRoutingDataSource+AOP实现多数据源切换

xiaoxiao2021-02-28  38

实现功能

实现基于springmvc+mybatis框架动态切换不同的数据源。

基础框架springmvc4+mybatis3

实现原理

主要利用了spring aop以及spring的AbstractRoutingDataSource类。

AbstractRoutingDataSource

通过观察源码,可以抽取该类中几个重要元素

properties:

private Map<Object, Object> targetDataSources; private Object defaultTargetDataSource;

functions:

@Override public void afterPropertiesSet() { if (this.targetDataSources == null) { throw new IllegalArgumentException("Property 'targetDataSources' is required"); } this.resolvedDataSources = new HashMap<Object, DataSource>(this.targetDataSources.size()); for (Map.Entry<Object, Object> entry : this.targetDataSources.entrySet()) { Object lookupKey = resolveSpecifiedLookupKey(entry.getKey()); DataSource dataSource = resolveSpecifiedDataSource(entry.getValue()); this.resolvedDataSources.put(lookupKey, dataSource); } if (this.defaultTargetDataSource != null) { this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource); } } public Connec tion 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; }

通过解读源码,可以知道,targetDataSources用来初始化预存的数据源,defaultTargetDataSource则是默认数据源,当determineTargetDataSource获取不到用户定义的数据源时,使用该默认数据源。在determineTargetDataSource中通过determineCurrentLookupKey来获取自定义数据源的KEY,这也正是我们要复写的方法。

如果每次方法调用都去手动切换数据源,一方面代码耦合度高,另一方面可维护性可扩展性差,因此我们利用spring aop编写pointcut去执行动态切换。

具体配置

spring配置文件(部分)

<!-- 主数据源 1--> <bean id="mysqlDataSource1" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> <property name="driverClass" value="${jdbc.master.driverClassName}" /> <property name="jdbcUrl" value="${jdbc.master.url}" /> <property name="user" value="${jdbc.master.username}" /> <property name="password" value="${jdbc.master.password}" /> <property name="initialPoolSize" value="${jdbc.master.c3p0.initialPoolSize}" /> <property name="minPoolSize" value="${jdbc.master.c3p0.min_size}" /> <property name="maxPoolSize" value="${jdbc.master.c3p0.max_size}" /> <property name="maxIdleTime" value="${jdbc.master.c3p0.max_idle_time}" /> <property name="acquireIncrement" value="${jdbc.master.c3p0.acquire_increment}" /> <property name="maxStatements" value="${jdbc.master.c3p0.max_statements}" /> <property name="idleConnectionTestPeriod" value="${jdbc.master.c3p0.idle_connection_test_period}" /> <property name="checkoutTimeout" value="${jdbc.master.c3p0.checkout_timeout}" /> <property name="testConnectionOnCheckin" value="${jdbc.master.c3p0.test_connection_on_checkin}" /> <property name="automaticTestTable" value="${jdbc.master.c3p0.automatic_test_table}" /> <property name="preferredTestQuery" value="${jdbc.master.c3p0.preferred_test_query}" /> </bean> <!-- 从数据源 2--> <bean id="mysqlDataSource2" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> <property name="driverClass" value="${jdbc.slave.driverClassName}" /> <property name="jdbcUrl" value="${jdbc.slave.url}" /> <property name="user" value="${jdbc.slave.username}" /> <property name="password" value="${jdbc.slave.password}" /> <property name="initialPoolSize" value="${jdbc.slave.c3p0.initialPoolSize}" /> <property name="minPoolSize" value="${jdbc.slave.c3p0.min_size}" /> <property name="maxPoolSize" value="${jdbc.slave.c3p0.max_size}" /> <property name="maxIdleTime" value="${jdbc.slave.c3p0.max_idle_time}" /> <property name="acquireIncrement" value="${jdbc.slave.c3p0.acquire_increment}" /> <property name="maxStatements" value="${jdbc.slave.c3p0.max_statements}" /> <property name="idleConnectionTestPeriod" value="${jdbc.slave.c3p0.idle_connection_test_period}" /> <property name="checkoutTimeout" value="${jdbc.slave.c3p0.checkout_timeout}" /> <property name="testConnectionOnCheckin" value="${jdbc.slave.c3p0.test_connection_on_checkin}" /> <property name="automaticTestTable" value="${jdbc.slave.c3p0.automatic_test_table}" /> <property name="preferredTestQuery" value="${jdbc.slave.c3p0.preferred_test_query}" /> </bean> <!-- 多数据源配置 --> <bean id="dataSource" class="com.test.tools.DynamicDataSource"> <property name="targetDataSources"> <map key-type="java.lang.String"> <entry value-ref="mysqlDataSource1" key="mysqlDataSource1"></entry> <entry value-ref="mysqlDataSource2" key="mysqlDataSource2"></entry> </map> </property> <property name="defaultTargetDataSource" ref="mysqlDataSource1"></property> </bean> <!-- sessionfactory1 --> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean" lazy-init="false" > <property name="configLocation" value="classpath:/mybatis/mybatis-config.xml" /> <property name="mapperLocations" value="classpath*:/mybatis/mappers/*.xml" /> <property name="dataSource" ref="dataSource" /> </bean> <bean name="mapperConf" class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="annotationClass" value="org.springframework.stereotype.Repository" /> <property name="basePackage" value="com.**.dao" /> </bean> ...... <!--使用aspectj创建aop --> <aop:aspectj-autoproxy/> <bean id="dataSourceAspect" class="com.test.aspect.DataSourceAspect"></bean> ......

jdbc配置文件如下

jdbc.master.driverClassName=com.mysql.jdbc.Driver jdbc.master.url=jdbc:mysql://127.0.0.1:3360/test2?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true jdbc.master.username=root jdbc.master.password=Landi12345 jdbc.master.c3p0.acquire_increment=2 jdbc.master.c3p0.initialPoolSize=2 jdbc.master.c3p0.min_size=2 jdbc.master.c3p0.max_size=10 jdbc.master.c3p0.max_idle_time=180 jdbc.master.c3p0.max_statements=0 jdbc.master.c3p0.idle_connection_test_period=180 jdbc.master.c3p0.checkout_timeout=30000 jdbc.master.c3p0.test_connection_on_checkin=true jdbc.master.c3p0.automatic_test_table=c3p0_test jdbc.master.c3p0.preferred_test_query=select * from "c3p0_test" jdbc.slave.driverClassName=com.mysql.jdbc.Driver jdbc.slave.url=jdbc:mysql://127.0.0.1:3306/test2?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true jdbc.slave.username=root jdbc.slave.password=Landi123456 jdbc.slave.c3p0.acquire_increment=2 jdbc.slave.c3p0.initialPoolSize=2 jdbc.slave.c3p0.min_size=2 jdbc.slave.c3p0.max_size=10 jdbc.slave.c3p0.max_idle_time=180 jdbc.slave.c3p0.max_statements=0 jdbc.slave.c3p0.idle_connection_test_period=180 jdbc.slave.c3p0.checkout_timeout=30000 jdbc.slave.c3p0.test_connection_on_checkin=true jdbc.slave.c3p0.automatic_test_table=c3p0_test jdbc.slave.c3p0.preferred_test_query=select * from "c3p0_test" jdbc.transation_timeout=1800

自定义注解类DataSource

import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; @Target({ElementType.TYPE,ElementType.METHOD}) @Retention(RetentionPolicy.RUNTIME) public @interface DataSource { String value(); }

数据源控制类DynamicDataSource、DynamicDataSourceHolder

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource; public class DynamicDataSource extends AbstractRoutingDataSource { @Override protected Object determineCurrentLookupKey() { return DynamicDataSourceHolder.getDataSourceType(); } } public class DynamicDataSourceHolder { // 线程局部变量(多线程并发设计,为了线程安全) private static final ThreadLocal<String> contextHolder = new ThreadLocal(); // 设置数据源类型 public static void setDataSourceType(String dataSourceType) { contextHolder.set(dataSourceType); } // 获取数据源类型 public static String getDataSourceType() { return (String) contextHolder.get(); } // 清除数据源类型 public static void clearDataSourceType() { contextHolder.remove(); } }

切面类DataSourceAspect ,用于控制切换,切入点为service

import org.apache.log4j.Logger; import org.aspectj.lang.JoinPoint; import org.aspectj.lang.annotation.After; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.aspectj.lang.annotation.Pointcut; import com.test.tools.DynamicDataSourceHolder; import com.test.utils.DataSource; @Aspect public class DataSourceAspect { private final static Logger log = Logger.getLogger(DataSourceAspect.class); @Before("execution(* com.test.service..*.*(..))&&@annotation(ds)") public void changeDataSource(JoinPoint point, DataSource ds) throws Throwable { String key = ds.value(); if(key!=null && !key.trim().equals("")){ DynamicDataSourceHolder.setDataSourceType(key); } } @After("execution(* com.test.service..*.*(..))&&@annotation(ds)") public void restoreDataSource(JoinPoint point, DataSource ds) { DynamicDataSourceHolder.clearDataSourceType(); } }

测试用的service,用于查询权限

编写一个测试用例

/** * * <br> * <b>功能:</b>SysAuthoService<br> */ @Service("sysauthoService") public class SysAuthoServiceImpl extends BaseServiceImpl implements SysAuthoService { private final static Logger log= Logger.getLogger(SysAuthoServiceImpl.class); @Resource private SysAuthoDao dao; public SysAuthoDao getDao() { return dao; } @DataSource(value="mysqlDataSource1") @Override public List<ListBean> readWebList(SysAutho queryObj) { return dao.readWebList(queryObj); } @DataSource(value="mysqlDataSource2") @Override public List<ListBean> readWebList2(SysAutho queryObj) { return dao.readWebList2(queryObj); } }

这里controller和mybatis的配置代码就不给出了,具体业务系统自己编写,测试数据中1库有数据,2库为空,最后测试效果如下:

转载请注明原文地址: https://www.6miu.com/read-2300029.html

最新回复(0)