标签:总结 end sqlmap 数据库连接 spring oid version etl 数据
前段时间刚换了家新公司,然后看项目代码里用了数据库读写分离的架构,然后好奇扒了代码简单看了下,总体来说就是运用spring aop切面方式来实现的。看明白后就在自己的个人小项目里运用了下,测试OK,所以下面总结下流程:
1、首先定义一个数据源注解,它有两个值,一个对应写库(主库),一个对应读库(从库)
package com.jdd.ds; import java.lang.annotation.*; @Target({ElementType.METHOD, ElementType.TYPE}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface DataSource { String DATA_SOURCE_READ = "dataSourceRead"; String DATA_SOURCE_WRITE = "dataSourceWrite"; String name() default "dataSourceWrite"; }
2、在需要拦截的方法上加上该注解
package com.jdd.service.impl; import com.jdd.dao.UserDao; import com.jdd.ds.DataSource; import com.jdd.pojo.User; import com.jdd.service.UserService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; @Service("userService") public class UserServiceImpl implements UserService{ @Autowired private UserDao userDao; @DataSource(name=DataSource.DATA_SOURCE_READ) @Override public User getUserByNameAndPassword(String name, String password) { return userDao.getUserByNameAndPassword(name, password); } @DataSource(name=DataSource.DATA_SOURCE_WRITE) @Override public int insertUser(User user) { return userDao.insertUser(user); } }
3、然后在配置文件里加上aop切面配置:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="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/aop http://www.springframework.org/schema/aop/spring-aop-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/util http://www.springframework.org/schema/util/spring-util-4.0.xsd"> <!-- 扫描包加载Service实现类 --> <context:component-scan base-package="com.jdd.service"></context:component-scan> <bean id="dataSourceExchange" class="com.jdd.ds.DataSourceExchange"></bean> <aop:config> <aop:aspect ref="dataSourceExchange"> <aop:around method="execute" pointcut="within(com.jdd.service.impl.*)"></aop:around> </aop:aspect> </aop:config> </beans>
4、然后我们要在切面类里,获取到方法上的dataSource注解里设置的值,从而决定使用哪个数据源
package com.jdd.ds; import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.Signature; import org.aspectj.lang.reflect.MethodSignature; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.lang.reflect.Method; public class DataSourceExchange { private static Logger logger = LoggerFactory.getLogger(DataSourceExchange.class); public Object execute(ProceedingJoinPoint pjp){ logger.info("DataSourceExchange==>"); Object obj = null; Signature signature = pjp.getSignature(); MethodSignature methodSignature = (MethodSignature)signature; Method targetMethod = methodSignature.getMethod(); Method realMethod = null; try { realMethod = pjp.getTarget().getClass().getDeclaredMethod(signature.getName(), targetMethod.getParameterTypes()); if(realMethod.isAnnotationPresent(DataSource.class)){ DataSource datasource = (DataSource) realMethod.getAnnotation(DataSource.class); DataSourceContext.setDbType(datasource.name()); logger.info(realMethod.getName() +" set dbtype==>"+datasource.name()); }else{ DataSourceContext.setDbType("dataSourceWrite"); } obj = pjp.proceed(); } catch (Throwable t) { t.printStackTrace(); } logger.info(realMethod.getName()+" clear datatype==>"); DataSourceContext.clearDbType(); return obj; } }
在方法执行前,设置具体数据源,然后方法执行完后,再清除掉该值。
注:注意上面的通过反射获取业务方法的代码, 开始的时候用
MethodSignature signature = (MethodSignature)pjp.getSignature();
Method method = signature.getMethod();
发现通过这种方法获取的method,它是没有注解信息的。后来在网上搜了下,大概说是这种方法获取的是代理方法,不是目标方法。代理方法是不带注解信息的,所以这块注意下。
5、下面看下 DataSourceContext 类,作用自然就是设置数据源上下文。
package com.jdd.ds; public class DataSourceContext { public static final String DATA_SOURCE_READ = "dataSourceRead"; public static final String DATA_SOURCE_WRITE = "dataSourceWrite"; private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>(); public DataSourceContext(){ } public static void setDbType(String dbType){ contextHolder.set(dbType); } public static String getDbType(){ return (String)contextHolder.get(); } public static void clearDbType(){ contextHolder.remove(); } }
6、下面定义 MultipleDataSource类, 继承与spring的 AbstractRoutingDataSource类, 并重写它的 determineCurrentLookupKey 方法, 作用就是从上下文获取当前线程使用的数据源标识:
package com.jdd.ds; import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource; public class MultipleDataSource extends AbstractRoutingDataSource{ @Override protected Object determineCurrentLookupKey() { Object key = DataSourceContext.getDbType(); if(key != null){ this.logger.info("当前线程使用的数据源标识为 [ " + key.toString() + " ]."); } return key; } }
7、最后在 配置文件 applicationContext-mysql.xml 里 配上数据源
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="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/aop http://www.springframework.org/schema/aop/spring-aop-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/util http://www.springframework.org/schema/util/spring-util-4.0.xsd"> <!-- 加载配置文件 --> <context:property-placeholder location="classpath:resource/*.properties" /> <!-- 数据库连接池 --> <bean id="dataSourceWrite" class="com.alibaba.druid.pool.DruidDataSource" destroy-method="close"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="${url.write}" /> <property name="username" value="${username.write}" /> <property name="password" value="${password.write}" /> <property name="maxActive" value="10" /> <property name="minIdle" value="5" /> </bean> <bean id="dataSourceRead" class="com.alibaba.druid.pool.DruidDataSource" destroy-method="close"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="${url.read}" /> <property name="username" value="${username.read}" /> <property name="password" value="${password.read}" /> <property name="maxActive" value="10" /> <property name="minIdle" value="5" /> </bean> <bean id="multipleDataSource" class="com.jdd.ds.MultipleDataSource"> <property name="defaultTargetDataSource" ref="dataSourceWrite" /> <property name="targetDataSources"> <map> <entry value-ref="dataSourceWrite" key="dataSourceWrite"></entry> <entry value-ref="dataSourceRead" key="dataSourceRead"></entry> </map> </property> </bean> <!-- sqlsessionFactory --> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="configLocation" value="classpath:mybatis/SqlMapConfig.xml"></property> <property name="dataSource" ref="multipleDataSource"></property> <property name="mapperLocations" value="classpath:com/jdd/mapper/*.xml"></property> </bean> </beans>
8、到这里和spring相关的配置基本就配完了, 其实后面还要再配置一下 mysql的主从复制,就是对写库的操作都同步到从库,这样写库从库的数据才一致。具体配置操作我就不写了,可以自行到网上搜索。
标签:总结 end sqlmap 数据库连接 spring oid version etl 数据
原文地址:https://www.cnblogs.com/xiexin2015/p/8998647.html