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Spring-基于Spring使用自定义注解及Aspect实现数据库切换操作

浏览：68日期：2023-08-13 11:44:07

实现思路

重写Spring的AbstractRoutingDataSource抽象类的determineCurrentLookupKey方法。

我们来看下Spring-AbstractRoutingDataSource的源码

AbstractRoutingDataSource获取数据源之前会先调用determineCurrentLookupKey方法查找当前的lookupKey。

Object lookupKey = determineCurrentLookupKey();DataSource dataSource = this.resolvedDataSources.get(lookupKey);.......return dataSource;

lookupKey为数据源标识，因此通过重写这个查找数据源标识的方法就可以让spring切换到指定的数据源.

从变量定义中可以知道resolvedDataSources为Map类型的对象。

private Map<Object, DataSource> resolvedDataSources;

示例

Spring-基于Spring使用自定义注解及Aspect实现数据库切换操作

步骤一新建Maven工程

依赖如下： pom.xml

<project xmlns='http://maven.apache.org/POM/4.0.0' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'xsi:schemaLocation='http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd'><modelVersion>4.0.0</modelVersion><groupId>com.artisan</groupId><artifactId>dynamicDataSource</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>dynamicDataSource</name><url>http://maven.apache.org</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><file.encoding>UTF-8</file.encoding><spring.version>4.3.9.RELEASE</spring.version><servlet.version>3.1.0</servlet.version><aspectj.version>1.8.1</aspectj.version><commons-dbcp.version>1.4</commons-dbcp.version><jetty.version>8.1.8.v20121106</jetty.version><log4j.version>1.2.17</log4j.version><log4j2.version>2.8.2</log4j2.version><testng.version>6.8.7</testng.version><oracle.version>11.2.0.4.0</oracle.version><jstl.version>1.2</jstl.version></properties><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-beans</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context-support</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>${spring.version}</version></dependency><dependency><groupId>commons-dbcp</groupId><artifactId>commons-dbcp</artifactId><version>${commons-dbcp.version}</version></dependency><dependency><groupId>org.aspectj</groupId><artifactId>aspectjweaver</artifactId><version>${aspectj.version}</version></dependency><dependency><groupId>org.testng</groupId><artifactId>testng</artifactId><version>${testng.version}</version><scope>test</scope></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-test</artifactId><version>${spring.version}</version><scope>test</scope></dependency><dependency><groupId>com.oracle</groupId><artifactId>ojdbc6</artifactId><version>${oracle.version}</version></dependency><dependency><groupId>org.testng</groupId><artifactId>testng</artifactId><version>${testng.version}</version><scope>test</scope></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-test</artifactId><version>${spring.version}</version><scope>test</scope></dependency><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-api</artifactId><version>${log4j2.version}</version></dependency><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-core</artifactId><version>${log4j2.version}</version></dependency></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.1</version><configuration><source>1.7</source><target>1.7</target></configuration></plugin></plugins></build></project>

步骤二 继承AbstractRoutingDataSource并重写determineCurrentLookupKey方法获取特定数据源

package com.artisan.dynamicDB;import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;/** * * * @ClassName: DynamicDataSource * * @Description: * AbstractRoutingDataSource中的抽象方法determineCurrentLookupKey是实现数据源的route的核心 * .需要重写该方法 * * @author: Mr.Yang * * @date: 2017年7月24日下午8:28:46 */public class DynamicDataSource extends AbstractRoutingDataSource {@Overrideprotected Object determineCurrentLookupKey() {return DynamicDataSourceHolder.getDataSource();}}

步骤三 创建DynamicDataSourceHolder用于持有当前线程中使用的数据源标识

package com.artisan.dynamicDB;/** * * * @ClassName: DynamicDataSourceHolder * * @Description:创建DynamicDataSourceHolder用于持有当前线程中使用的数据源标识 * * @author: Mr.Yang * * @date: 2017年7月24日下午8:23:50 */public class DynamicDataSourceHolder { /** * 数据源标识保存在线程变量中，避免多线程操作数据源时互相干扰 */ private static final ThreadLocal<String> dataSourceHolder = new ThreadLocal<String>(); /** * * * @Title: setDataSource * * @Description: 设置数据源 * * @param dataSource * * @return: void */ public static void setDataSource(String dataSource) { dataSourceHolder.set(dataSource); } /** * * * @Title: getDataSource * * @Description: 获取数据源 * * @return * * @return: String */ public static String getDataSource() { return dataSourceHolder.get(); } /** * * * @Title: clearDataSource * * @Description: 清除数据源 * * * @return: void */ public static void clearDataSource() { dataSourceHolder.remove(); }}

步骤四 配置多个数据源和DynamicDataSource的bean

<?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:tx='http://www.springframework.org/schema/tx' xmlns:util='http://www.springframework.org/schema/util' xsi:schemaLocation='http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.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 http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd'>  <context:component-scan base-package='com.artisan'/>  <context:property-placeholder location='classpath:jdbc.properties' />   <bean destroy-method='close' p:driverClassName='${jdbc.driverClassNamePR}' p:url='${jdbc.urlPR}' p:username='${jdbc.usernamePR}' p:password='${jdbc.passwordPR}' />  <bean destroy-method='close' p:driverClassName='${jdbc.driverClassNameDR}' p:url='${jdbc.urlDR}' p:username='${jdbc.usernameDR}' p:password='${jdbc.passwordDR}' />  <bean destroy-method='close' p:driverClassName='${jdbc.driverClassNameCC}' p:url='${jdbc.urlCC}' p:username='${jdbc.usernameCC}' p:password='${jdbc.passwordCC}' /> <bean class='com.artisan.dynamicDB.DynamicDataSource'> <property name='targetDataSources' ref='dynamicDatasourceMap' />  <property name='defaultTargetDataSource' ref='dataSourcePR' /> </bean>  <util:map key-type='java.lang.String'> <entry key='dataSourcePR' value-ref='dataSourcePR' /> <entry key='dataSourceDR' value-ref='dataSourceDR' /> <entry key='dataSourceCC' value-ref='dataSourceCC' /> </util:map>  <bean p:dataSource-ref='dynamicDataSource' />  <bean /> <aop:config> <aop:aspect ref='dataSourceAspect'>  <aop:pointcut expression='execution(* com.artisan..*(..))'/> <aop:before pointcut-ref='dataSourcePointcut' method='intercept' /> </aop:aspect> </aop:config>  <bean p:dataSource-ref='dynamicDataSource' />  <aop:config proxy-target-class='true'> <aop:pointcut expression='(execution(* com.artisan..*(..))) and (@annotation(org.springframework.transaction.annotation.Transactional))' /> <aop:advisor pointcut-ref='serviceMethod' advice-ref='txAdvice' /> </aop:config> <tx:advice transaction-manager='transactionManager'> <tx:attributes> <tx:method name='*' /> </tx:attributes> </tx:advice></beans>

配置到这里，我们就可以使用多个数据源了，只需要在操作数据库之前只要DynamicDataSourceHolder.setDataSource(“dataSourcePR”)即可切换到数据源dataSourcePR并对数据库dataSourcePR进行操作了。

问题：每次使用都需要调用DynamicDataSourceHolder#setDataSource，十分繁琐，并且难以维护。

我们可以通过Spring的AOP和注解，直接通过注解的方式指定需要访问的数据源。继续改进下吧

步骤五 定义名为@DataSource的注解

package com.artisan.dynamicDB;import java.lang.annotation.Documented;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;/** * * * @ClassName: DataSource * * * @Description: 注解@DataSource既可以加在方法上，也可以加在接口或者接口的实现类上，优先级别：方法>实现类>接口。 * 如果接口、接口实现类以及方法上分别加了@DataSource注解来指定数据源，则优先以方法上指定的为准。 * * @author: Mr.Yang * * @date: 2017年7月24日下午9:59:29 */@Target({ ElementType.METHOD, ElementType.TYPE })@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface DataSource { // 和配置文件中 dynamicDatasourceMap中的key保持一致 public static String PR_RB = 'dataSourcePR'; public static String DR_RB = 'dataSourceDR'; public static String PR_CC = 'dataSourceCC'; /** * * * @Title: name * * @Description: 如果仅标注@DataSource 默认为PR_RB数据库实例 * * @return * * @return: String */ String name() default DataSource.PR_RB;}

步骤六 定义AOP切面以便拦截所有带有注解@DataSource的方法，取出注解的值作为数据源标识放到DynamicDataSourceHolder的线程变量中

package com.artisan.dynamicDB;import java.lang.reflect.Method;import org.aspectj.lang.JoinPoint;import org.aspectj.lang.reflect.MethodSignature;/** * * * @ClassName: DataSourceAspect * * @Description: * 定义AOP切面以便拦截所有带有注解@DataSource的方法，取出注解的值作为数据源标识放到DBContextHolder的线程变量中 * * @author: Mr.Yang * * @date: 2017年7月25日上午10:51:41 */public class DataSourceAspect { /** * * * @Title: intercept * * @Description: 拦截目标方法，获取由@DataSource指定的数据源标识，设置到线程存储中以便切换数据源 * * @param point * @throws Exception * * @return: void */ public void intercept(JoinPoint point) throws Exception { Class<?> target = point.getTarget().getClass(); MethodSignature signature = (MethodSignature) point.getSignature(); // 默认使用目标类型的注解，如果没有则使用其实现接口的注解 for (Class<?> clazz : target.getInterfaces()) { resolveDataSource(clazz, signature.getMethod()); } resolveDataSource(target, signature.getMethod()); } /** * * * @Title: resolveDataSource * * @Description: 提取目标对象方法注解和类型注解中的数据源标识 * * @param clazz * @param method * * @return: void */ private void resolveDataSource(Class<?> clazz, Method method) { try { Class<?>[] types = method.getParameterTypes(); // 默认使用类型注解 if (clazz.isAnnotationPresent(DataSource.class)) { DataSource source = clazz.getAnnotation(DataSource.class); DynamicDataSourceHolder.setDataSource(source.name()); } // 方法注解可以覆盖类型注解 Method m = clazz.getMethod(method.getName(), types); if (m != null && m.isAnnotationPresent(DataSource.class)) { DataSource source = m.getAnnotation(DataSource.class); DynamicDataSourceHolder.setDataSource(source.name()); } } catch (Exception e) { System.out.println(clazz + ':' + e.getMessage()); } }}

步骤七 在spring配置文件中配置拦截规则

<bean /> <aop:config> <aop:aspect ref='dataSourceAspect'>  <aop:pointcut expression='execution(* com.artisan..*(..))'/> <aop:before pointcut-ref='dataSourcePointcut' method='intercept' /> </aop:aspect> </aop:config>

步骤八 使用注解切换多数据源

ExtractDataService.javapackage com.artisan.extractService;import java.sql.ResultSet;import java.sql.SQLException;import org.apache.logging.log4j.LogManager;import org.apache.logging.log4j.Logger;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.jdbc.core.JdbcTemplate;import org.springframework.jdbc.core.RowCallbackHandler;import org.springframework.stereotype.Service;import com.artisan.dynamicDB.DataSource;/** * * * @ClassName: ExtractDataService * * @Description: 业务类，这里暂时作为测试多数据源切换用 * * @author: Mr.Yang * * @date: 2017年7月24日下午9:07:38 */@Servicepublic class ExtractDataService { private static final Logger logger = LogManager .getLogger(ExtractDataService.class.getName()); private JdbcTemplate jdbcTemplate; @Autowired public void setJdbcTemplate(JdbcTemplate jdbcTemplate) { this.jdbcTemplate = jdbcTemplate; } /** * * * @Title: selectDataFromPR * * @Description: * * * @return: void */ @DataSource(name = DataSource.PR_RB) public void selectDataFromPR_RB() { String sql = 'select subs_id from owe_event_charge where event_inst_id = 10229001 '; jdbcTemplate.query(sql, new RowCallbackHandler() { @Override public void processRow(ResultSet rs) throws SQLException { logger.info(rs.getInt('subs_id')); } }); } @DataSource(name = DataSource.DR_RB) public void selectDataFromDR_RB() { // 改为通过注解指定DB // DynamicDataSourceHolder.setDataSource(DBContextHolder.DATA_SOURCE_DR); String sql = ' select a.task_comments from nm_task_type a where a.task_name = ’ALARM_LOG_LEVEL’ '; jdbcTemplate.query(sql, new RowCallbackHandler() { @Override public void processRow(ResultSet rs) throws SQLException { logger.info(rs.getString('task_comments')); } }); } @DataSource(name = DataSource.PR_CC) public void selectDataFromPR_CC() { // DBContextHolder.setDataSource(DBContextHolder.DATA_SOURCE_CC); String sql = 'select acc_nbr from acc_nbr where acc_nbr_id = 82233858 '; jdbcTemplate.query(sql, new RowCallbackHandler() { @Override public void processRow(ResultSet rs) throws SQLException { logger.info(rs.getString('acc_nbr')); } }); }}

步骤九测试

package com.artisan;import java.io.IOException;import org.apache.logging.log4j.LogManager;import org.apache.logging.log4j.core.LoggerContext;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import org.springframework.core.io.Resource;import org.springframework.core.io.ResourceLoader;import org.springframework.core.io.support.PathMatchingResourcePatternResolver;import com.artisan.extractService.ExtractDataService;/** * * * @ClassName: App * * @Description: 入口类 * * @author: Mr.Yang * * @date: 2017年7月24日下午8:50:25 */public class App { public static void main(String[] args) { try { // 加载日志框架 log4j2 LoggerContext context = (LoggerContext) LogManager .getContext(false); ResourceLoader loader = new PathMatchingResourcePatternResolver(); Resource resource = loader.getResource('classpath:log4j2.xml'); context.setConfigLocation(resource.getFile().toURI()); // 加载spring配置信息 ApplicationContext ctx = new ClassPathXmlApplicationContext( 'classpath:spring-context.xml'); // 从容器中获取Bean ExtractDataService service = ctx.getBean('extractDataService', ExtractDataService.class); // 从PR的RB实例中获取数据 service.selectDataFromPR_RB(); // 从DR的RB实例中获取数据 service.selectDataFromDR_RB(); // 从PR的CC实例中获取数据 service.selectDataFromPR_CC(); } catch (IOException e) { e.printStackTrace(); } }}

其他代码

log4j2.xml

<?xml version='1.0' encoding='UTF-8'?><configuration status='info' monitorInterval='180'>  <Properties> <Property name='backupFilePatch'>D:/workspace/workspace-sts/backupOracle/log/</Property> <Property name='fileName'>backupOracle.log</Property> </Properties>  <appenders>  <Console name='Console' target='SYSTEM_OUT'>  <ThresholdFilter level='trace' onMatch='ACCEPT' onMismatch='DENY' />  <PatternLayout pattern='%d{HH:mm:ss.SSS} %-5level %class{36} %L %M - %msg%xEx%n' /> </Console>  <RollingFile name='RollingFile' fileName='${backupFilePatch}${fileName}' filePattern='${backupFilePatch}$${date:yyyy-MM}/app-%d{yyyyMMddHHmmssSSS}.log.gz'> <PatternLayout pattern='%d{yyyy.MM.dd ’at’ HH:mm:ss.SSS z} %-5level %class{36} %L %M - %msg%xEx%n' />  <SizeBasedTriggeringPolicy size='20MB' />  <DefaultRolloverStrategy max='20'/> </RollingFile> </appenders>  <loggers>  <logger name='org.springframework' level='INFO'></logger> <logger name='org.mybatis' level='INFO'></logger> <root level='trace'> <appender-ref ref='RollingFile'/> <appender-ref ref='Console'/> </root> </loggers></configuration>

jdbc.properties

################################ dbcp datasource pool ,basic configuration first.## the other parameters keep default for now , you can change them if you want ###############################Database in Lapazjdbc.driverClassNamePR=oracle.jdbc.driver.OracleDriverjdbc.urlPR=jdbc:oracle:thin:@172.25.243.4:1521:xxjdbc.usernamePR=xxxjdbc.passwordPR=xxxxxxxx#Database in Scluzjdbc.driverClassNameDR=oracle.jdbc.driver.OracleDriverjdbc.urlDR=jdbc:oracle:thin:@172.25.246.1:1521:xxjdbc.usernameDR=xxxjdbc.passwordDR=xxxxxxx#Database in Lapazjdbc.driverClassNameCC=oracle.jdbc.driver.OracleDriverjdbc.urlCC=jdbc:oracle:thin:@172.25.243.3:1521:xxjdbc.usernameCC=xxxjdbc.passwordCC=xxxxxx

运行结果：

Spring-基于Spring使用自定义注解及Aspect实现数据库切换操作

代码

https://github.com/yangshangwei/DynamicDataSource

以上这篇Spring-基于Spring使用自定义注解及Aspect实现数据库切换操作就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持好吧啦网。

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