SpringBoot整合多数据源，并支持动态新增与切换

一、概述

在项目的开发过程中，遇到了需要从数据库中动态查询新的数据源信息并切换到该数据源做相应的查询操作，这样就产生了动态切换数据源的场景。为了能够灵活地指定具体的数据库，本文基于注解和AOP的方法实现多数据源自动切换。在使用过程中，只需要添加注解就可以使用，简单方便。(代码获取方式：见文章底部(开箱即用)）

二、构建核心代码

2.1、AbstractRoutingDataSource构建

package com.wonders.dynamic;import org.springframework.beans.factory.InitializingBean;
import org.springframework.jdbc.datasource.AbstractDataSource;
import org.springframework.jdbc.datasource.lookup.DataSourceLookup;
import org.springframework.jdbc.datasource.lookup.JndiDataSourceLookup;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.CollectionUtils;import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Map;/*** @Description: TODO：抽象类AbstractRoutingDataSource，实现动态数据源切换* @Author: yyalin* @CreateDate: 2023/7/16 14:40* @Version: V1.0*/
public abstract class AbstractRoutingDataSource extends AbstractDataSourceimplements InitializingBean {//目标数据源map集合，存储将要切换的多数据源bean信息@Nullableprivate Map<Object, Object> targetDataSources;//未指定数据源时的默认数据源对象@Nullableprivate Object defaultTargetDataSource;private boolean lenientFallback = true;//数据源查找接口，通过该接口的getDataSource(String dataSourceName)获取数据源信息private DataSourceLookup dataSourceLookup = new JndiDataSourceLookup();//解析targetDataSources之后的DataSource的map集合@Nullableprivate Map<Object, DataSource> resolvedDataSources;@Nullableprivate DataSource resolvedDefaultDataSource;//将targetDataSources的内容转化一下放到resolvedDataSources中，将defaultTargetDataSource转为DataSource赋值给resolvedDefaultDataSourcepublic void afterPropertiesSet() {//如果目标数据源为空，会抛出异常，在系统配置时应至少传入一个数据源if (this.targetDataSources == null) {throw new IllegalArgumentException("Property 'targetDataSources' is required");} else {//初始化resolvedDataSources的大小this.resolvedDataSources = CollectionUtils.newHashMap(this.targetDataSources.size());//遍历目标数据源信息map集合，对其中的key，value进行解析this.targetDataSources.forEach((key, value) -> {//resolveSpecifiedLookupKey方法没有做任何处理，只是将key继续返回Object lookupKey = this.resolveSpecifiedLookupKey(key);//将目标数据源map集合中的value值（德鲁伊数据源信息）转为DataSource类型DataSource dataSource = this.resolveSpecifiedDataSource(value);//将解析之后的key，value放入resolvedDataSources集合中this.resolvedDataSources.put(lookupKey, dataSource);});if (this.defaultTargetDataSource != null) {//将默认目标数据源信息解析并赋值给resolvedDefaultDataSourcethis.resolvedDefaultDataSource = this.resolveSpecifiedDataSource(this.defaultTargetDataSource);}}}protected Object resolveSpecifiedLookupKey(Object lookupKey) {return lookupKey;}protected DataSource resolveSpecifiedDataSource(Object dataSource) throws IllegalArgumentException {if (dataSource instanceof DataSource) {return (DataSource)dataSource;} else if (dataSource instanceof String) {return this.dataSourceLookup.getDataSource((String)dataSource);} else {throw new IllegalArgumentException("Illegal data source value - only [javax.sql.DataSource] and String supported: " + dataSource);}}//因为AbstractRoutingDataSource继承AbstractDataSource，而AbstractDataSource实现了DataSource接口，所有存在获取数据源连接的方法public Connection getConnection() throws SQLException {return this.determineTargetDataSource().getConnection();}public Connection getConnection(String username, String password) throws SQLException {return this.determineTargetDataSource().getConnection(username, password);}protected DataSource determineTargetDataSource() {Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");//调用实现类中重写的determineCurrentLookupKey方法拿到当前线程要使用的数据源的名称Object lookupKey = this.determineCurrentLookupKey();//去解析之后的数据源信息集合中查询该数据源是否存在，如果没有拿到则使用默认数据源resolvedDefaultDataSourceDataSource 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 + "]");} else {return dataSource;}}@Nullableprotected abstract Object determineCurrentLookupKey();
}

**2.2、**DynamicDataSource类

/*** @Description: TODO：动态数据源* @Author: yyalin* @CreateDate: 2023/7/16 14:46* @Version: V1.0*/
/**** 调用AddDefineDataSource组件的addDefineDynamicDataSource（）方法，获取原来targetdatasources的map，* 并将新的数据源信息添加到map中，并替换targetdatasources中的map* 切换数据源时可以使用@DataSource(value = "数据源名称")，或者DynamicDataSourceContextHolder.setContextKey("数据源名称")*/
@Data
@AllArgsConstructor
@NoArgsConstructor
public class DynamicDataSource extends AbstractRoutingDataSource {//备份所有数据源信息，private Map<Object, Object> defineTargetDataSources;/*** 决定当前线程使用哪个数据源*/@Overrideprotected Object determineCurrentLookupKey() {return DynamicDataSourceHolder.getDynamicDataSourceKey();}}

2.3、DynamicDataSourceHolder

/*** @Description: TODO:数据源切换处理* DynamicDataSourceHolder类主要是设置当前线程的数据源名称，* 移除数据源名称，以及获取当前数据源的名称，便于动态切换* @Author: yyalin* @CreateDate: 2023/7/16 14:51* @Version: V1.0*/
@Slf4j
public class DynamicDataSourceHolder {/*** 保存动态数据源名称*/private static final ThreadLocal<String> DYNAMIC_DATASOURCE_KEY = new ThreadLocal<>();/*** 设置/切换数据源，决定当前线程使用哪个数据源*/public static void setDynamicDataSourceKey(String key){log.info("数据源切换为：{}",key);DYNAMIC_DATASOURCE_KEY.set(key);}/*** 获取动态数据源名称，默认使用mater数据源*/public static String getDynamicDataSourceKey(){String key = DYNAMIC_DATASOURCE_KEY.get();return key == null ? DbsConstant.mysql_db_01 : key;}/*** 移除当前数据源*/public static void removeDynamicDataSourceKey(){log.info("移除数据源：{}",DYNAMIC_DATASOURCE_KEY.get());DYNAMIC_DATASOURCE_KEY.remove();}}

2.4、数据源工具类

/*** @Description: TODO：数据源工具类* @Author: yyalin* @CreateDate: 2023/7/16 15:00* @Version: V1.0*/
@Slf4j
@Component
public class DataSourceUtils {@ResourceDynamicDataSource dynamicDataSource;/*** @Description: 根据传递的数据源信息测试数据库连接* @Author zhangyu*/public DruidDataSource createDataSourceConnection(DataSourceInfo dataSourceInfo) {DruidDataSource druidDataSource = new DruidDataSource();druidDataSource.setUrl(dataSourceInfo.getUrl());druidDataSource.setUsername(dataSourceInfo.getUserName());druidDataSource.setPassword(dataSourceInfo.getPassword());druidDataSource.setDriverClassName(dataSourceInfo.getDriverClassName());druidDataSource.setBreakAfterAcquireFailure(true);druidDataSource.setConnectionErrorRetryAttempts(0);try {druidDataSource.getConnection(2000);log.info("数据源连接成功");return druidDataSource;} catch (SQLException throwables) {log.error("数据源 {} 连接失败,用户名：{}，密码 {}",dataSourceInfo.getUrl(),dataSourceInfo.getUserName(),dataSourceInfo.getPassword());return null;}}/*** @Description: 将新增的数据源加入到备份数据源map中* @Author zhangyu*/public void addDefineDynamicDataSource(DruidDataSource druidDataSource, String dataSourceName){Map<Object, Object> defineTargetDataSources = dynamicDataSource.getDefineTargetDataSources();defineTargetDataSources.put(dataSourceName, druidDataSource);dynamicDataSource.setTargetDataSources(defineTargetDataSources);dynamicDataSource.afterPropertiesSet();}

2.5、DynamicDataSourceConfig

/*** @Description: TODO：数据源信息配置类，读取数据源配置信息并注册成bean。* @Author: yyalin* @CreateDate: 2023/7/16 14:54* @Version: V1.0*/
@Configuration
@MapperScan("com.wonders.mapper")
@Slf4j
public class DynamicDataSourceConfig {@Bean(name = DbsConstant.mysql_db_01)@ConfigurationProperties("spring.datasource.mysqldb01")public DataSource masterDataSource() {log.info("数据源切换为：{}",DbsConstant.mysql_db_01);DruidDataSource dataSource = DruidDataSourceBuilder.create().build();return dataSource;}@Bean(name = DbsConstant.mysql_db_02)@ConfigurationProperties("spring.datasource.mysqldb02")public DataSource slaveDataSource() {log.info("数据源切换为：{}",DbsConstant.mysql_db_02);DruidDataSource dataSource = DruidDataSourceBuilder.create().build();return dataSource;}@Bean(name = DbsConstant.oracle_db_01)@ConfigurationProperties("spring.datasource.oracledb01")public DataSource oracleDataSource() {log.info("数据源切换为oracle：{}",DbsConstant.oracle_db_01);DruidDataSource dataSource = DruidDataSourceBuilder.create().build();return dataSource;}@Bean@Primarypublic DynamicDataSource dynamicDataSource(){Map<Object, Object> dataSourceMap = new HashMap<>(3);dataSourceMap.put(DbsConstant.mysql_db_01,masterDataSource());dataSourceMap.put(DbsConstant.mysql_db_02,slaveDataSource());dataSourceMap.put(DbsConstant.oracle_db_01,oracleDataSource());//设置动态数据源DynamicDataSource dynamicDataSource = new DynamicDataSource();dynamicDataSource.setDefaultTargetDataSource(masterDataSource());dynamicDataSource.setTargetDataSources(dataSourceMap);//将数据源信息备份在defineTargetDataSources中dynamicDataSource.setDefineTargetDataSources(dataSourceMap);return dynamicDataSource;}}

三、测试代码

/*** @Description: TODO* @Author: yyalin* @CreateDate: 2023/7/16 15:02* @Version: V1.0*/
@Slf4j
@Api(tags="动态切换多数据源测试")
@RestController
public class TestController {@ResourceDataSourceUtils dataSourceUtils;@Autowiredprivate StudentMapper studentMapper;@ApiOperation(value="动态切换多数据源测试", notes="test")@GetMapping("/test")public Map<String, Object> dynamicDataSourceTest(String id){Map<String, Object> map = new HashMap<>();//1、默认库中查询数据Student student=studentMapper.selectById(id);map.put("1、默认库中查询到的数据",student);//2、指定库中查询的数据DynamicDataSourceHolder.setDynamicDataSourceKey(DbsConstant.mysql_db_02);Student student02=studentMapper.selectById(id);map.put("2、指定库中查询的数据",student02);//3、从数据库获取连接信息，然后获取数据//模拟从数据库中获取的连接DataSourceInfo dataSourceInfo = new DataSourceInfo("jdbc:mysql://127.0.0.1:3308/test02?useUnicode=true&characterEncoding=utf-8&useSSL=false","root","root","mysqldb03","com.mysql.cj.jdbc.Driver");map.put("dataSource",dataSourceInfo);log.info("数据源信息：{}",dataSourceInfo);//测试数据源连接DruidDataSource druidDataSource = dataSourceUtils.createDataSourceConnection(dataSourceInfo);if (Objects.nonNull(druidDataSource)){//将新的数据源连接添加到目标数据源map中dataSourceUtils.addDefineDynamicDataSource(druidDataSource,dataSourceInfo.getDatasourceKey());//设置当前线程数据源名称-----代码形式DynamicDataSourceHolder.setDynamicDataSourceKey(dataSourceInfo.getDatasourceKey());//在新的数据源中查询用户信息Student student03=studentMapper.selectById(id);map.put("3、动态数据源查询的数据",student03);//关闭数据源连接druidDataSource.close();}//4、指定oracle库中查询的数据DynamicDataSourceHolder.setDynamicDataSourceKey(DbsConstant.oracle_db_01);Student student04=studentMapper.selectById(id);map.put("4、指定oracle库中查询的数据",student04);return map;}
}

测试结果如下：

​ 从结果中可以明显的看出，通过切换不同的数据源，可以从不同的库中获取不同的数据，包括：常见库Mysql、oracle、sqlserver等数据库相互切换。也可以从数据库的某张表中获取连接信息，实现*动态切换数据库。*

四、使用注解方式切换数据源

从上述TestController 中代码不难看出，若要想切换数据源需要在mapper调用之前调用：

DynamicDataSourceHolder.setDynamicDataSourceKey(DbsConstant.mysql_db_02);

不够简洁优雅，所以下面推荐使用注解的方式来动态进行数据源的切换。

4.1、创建注解类DataSource

/*** @Description: TODO:自定义多数据源切换注解* 优先级：先方法，后类，如果方法覆盖了类上的数据源类型，以方法的为准，否则以类上的为准* @Author: yyalin* @CreateDate: 2023/7/17 14:00* @Version: V1.0*/
@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
public @interface DataSource {//切换数据源名称，默认mysql_db_01public String value() default DbsConstant.mysql_db_01;
}

**4.2、**创建切面DataSourceAspect类

/*** @Description: TODO:创建切面DataSourceAspect类* @Author: yyalin* @CreateDate: 2023/7/17 14:03* @Version: V1.0*/
@Aspect
@Component
public class DataSourceAspect {// 设置DataSource注解的切点表达式@Pointcut("@annotation(com.wonders.dynamic.DataSource)")public void dynamicDataSourcePointCut(){}//环绕通知@Around("dynamicDataSourcePointCut()")public Object around(ProceedingJoinPoint joinPoint) throws Throwable{String key = getDefineAnnotation(joinPoint).value();DynamicDataSourceHolder.setDynamicDataSourceKey(key);try {return joinPoint.proceed();} finally {DynamicDataSourceHolder.removeDynamicDataSourceKey();}}/*** 功能描述:先判断方法的注解，后判断类的注解，以方法的注解为准* @MethodName: getDefineAnnotation* @MethodParam: [joinPoint]* @Return: com.wonders.dynamic.DataSource* @Author: yyalin* @CreateDate: 2023/7/17 14:09*/private DataSource getDefineAnnotation(ProceedingJoinPoint joinPoint){MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature();DataSource dataSourceAnnotation = methodSignature.getMethod().getAnnotation(DataSource.class);if (Objects.nonNull(methodSignature)) {return dataSourceAnnotation;} else {Class<?> dsClass = joinPoint.getTarget().getClass();return dsClass.getAnnotation(DataSource.class);}}
}

4.3、进行数据源切换

//@Mapper 与 启动类的@MapperScan({"com.example.demo.mapper"}) 二选一即可
@Repository
public interface StudentMapper extends BaseMapper<Student> {/*** 功能描述:在mysql_db_01中查询数据* @MethodName: findStudentById* @MethodParam: [id]* @Return: com.wonders.entity.Student* @Author: yyalin* @CreateDate: 2023/7/17 14:20*/@DataSource(value = DbsConstant.oracle_db_01)Student findStudentById(String id);
}

或在service层

@Service
public class StudentServiceImpl implements StudentService{@Autowiredprivate StudentMapper studentMapper;//注解加在实现层才能生效@DataSource(value = DbsConstant.mysql_db_01)@Overridepublic Student findStudentById(String id) {return studentMapper.selectById(id);}
}

4.4、测试效果

@ApiOperation(value="使用注解方式动态切换多数据源", notes="test02")@GetMapping("/test02")public Student test02(String id){Student student=studentMapper.findStudentById(id);return student;}

–结果如下：

五、功能点

1、使用注解的方式来动态进行数据源的切换;

2、支持动态新增新的数据源;

3、支持oracle\mysql等常见数据库切换。