一. 示例代码 

1. 多数据源切换自定义注解

   package com.gateway.admin.datasources.annotation;import java.lang.annotation.*;
   /*** 多数据源注解*/
   @Target(ElementType.METHOD)
   @Retention(RetentionPolicy.RUNTIME)
   @Documented
   public @interface DataSource {String name() default "";
   }
   

2. 多数据源,切面处理类

   package com.gateway.admin.datasources;import com.gateway.admin.datasources.annotation.DataSource;
   import org.aspectj.lang.ProceedingJoinPoint;
   import org.aspectj.lang.annotation.Around;
   import org.aspectj.lang.annotation.Aspect;
   import org.aspectj.lang.annotation.Pointcut;
   import org.aspectj.lang.reflect.MethodSignature;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import org.springframework.core.Ordered;
   import org.springframework.stereotype.Component;import java.lang.reflect.Method;/*** 多数据源，切面处理类*/
   @Aspect
   @Component
   public class DataSourceAspect implements Ordered {protected Logger logger = LoggerFactory.getLogger(getClass());/*** 针对上面注解做切面拦截*/@Pointcut("@annotation(com.gateway.admin.datasources.annotation.DataSource)")public void dataSourcePointCut() {}@Around("dataSourcePointCut()")public Object around(ProceedingJoinPoint point) throws Throwable {MethodSignature signature = (MethodSignature) point.getSignature();Method method = signature.getMethod();DataSource ds = method.getAnnotation(DataSource.class);if(ds == null){//如果没有注解,使用默认数据源DynamicDataSource.setDataSource(DataSourceNames.FIRST);}else {//根据注解中设置的数据源名称,选择对应的数据源DynamicDataSource.setDataSource(ds.name());logger.debug("set datasource is " + ds.name());}try {return point.proceed();} finally {//清除数据源配置DynamicDataSource.clearDataSource();}}@Overridepublic int getOrder() {return 1;}
   }
   

3. 动态数据源类,需要继承:AbstractRoutingDataSource

   package com.gateway.admin.datasources;import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
   import javax.sql.DataSource;
   import java.util.Map;/*** 动态数据源*/
   public class DynamicDataSource extends AbstractRoutingDataSource {private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();public DynamicDataSource(DataSource defaultTargetDataSource, Map<Object, Object> targetDataSources) {super.setDefaultTargetDataSource(defaultTargetDataSource);super.setTargetDataSources(targetDataSources);super.afterPropertiesSet();}@Overrideprotected Object determineCurrentLookupKey() {return getDataSource();}public static void setDataSource(String dataSource) {contextHolder.set(dataSource);}public static String getDataSource() {return contextHolder.get();}public static void clearDataSource() {contextHolder.remove();}}

   4 .数据源名称配置

   package com.gateway.admin.datasources;/*** 多数据源配置数据源*/
   public interface DataSourceNames {String FIRST = "first";String SECOND = "second";String THREE = "three";String FOUR = "four";
   }
   

   5 .多数据源配置类

   package com.gateway.admin.datasources;import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
   import org.springframework.boot.context.properties.ConfigurationProperties;
   import org.springframework.context.annotation.Bean;
   import org.springframework.context.annotation.Configuration;
   import org.springframework.context.annotation.Primary;import javax.sql.DataSource;
   import java.util.HashMap;
   import java.util.Map;/*** 多数据源配置类*/
   @Configuration
   public class DynamicDataSourceConfig {//如果ioc容器中,同一个类型有多个bean,则bean的名称为方法的名称@Bean@ConfigurationProperties("spring.datasource.druid.first")public DataSource firstDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@ConfigurationProperties("spring.datasource.druid.second")public DataSource secondDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@ConfigurationProperties("spring.datasource.druid.three")public DataSource threeDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@ConfigurationProperties("spring.datasource.druid.four")public DataSource fourDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@Primary // Primary 一定要写在这里，写上面任意一个bean相当于指定唯一数据源public DynamicDataSource dataSource(DataSource firstDataSource, DataSource secondDataSource, DataSource threeDataSource, DataSource fourDataSource) {Map<Object, Object> targetDataSources = new HashMap<>();targetDataSources.put(DataSourceNames.FIRST, firstDataSource);targetDataSources.put(DataSourceNames.SECOND, secondDataSource);targetDataSources.put(DataSourceNames.THREE, threeDataSource);targetDataSources.put(DataSourceNames.FOUR, fourDataSource);return new DynamicDataSource(firstDataSource, targetDataSources);}
   }
   

         6.多数据源配置类

spring:datasource:type: com.alibaba.druid.pool.DruidDataSourcedriverClassName: com.mysql.jdbc.Driverdruid:first:  #db1url: jdbc:mysql://127.0.0.1:3306/db1?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=UTCusername: rootpassword: rootsecond:  #db2url: jdbc:mysql://127.0.0.1:3306/db2?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=UTCusername: rootpassword: rootthree:  #db3url: jdbc:mysql://127.0.0.1:3306/db3?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=UTCusername: rootpassword: rootfour:   #db4url: jdbc:mysql://127.0.0.1:3306/db4?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=UTCusername: rootpassword: root

        7.单侧

@Service
public class SysConfigServerce {@AutowiredSysConfigMapper sysConfigMapper;@DataSource(name = DataSourceNames.FIRST)public SysConfig select(SysConfig sysConfig){return sysConfigMapper.selectConfig(sysConfig);}
}public class DynamicDataSourceTest extends BaseTest{@Autowiredprivate SysConfigServerce sysConfigServerce;@Testpublic void test(){SysConfig sysConfig = new SysConfig();sysConfig.setConfigId(1L);SysConfig sysConfig1 = sysConfigServerce.select(sysConfig);System.out.println(sysConfig1);}
}

 

二. AbstractRoutingDataSource 补充

部分源码分析

public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {@Nullable//目标数据源private Map<Object, Object> targetDataSources;@Nullable//默认数据源private Object defaultTargetDataSource;@Nullable//解析的数据源private Map<Object, DataSource> resolvedDataSources;@Nullable//解析默认的数据源private DataSource resolvedDefaultDataSource;@Overridepublic void afterPropertiesSet() {if (this.targetDataSources == null) {throw new IllegalArgumentException("Property 'targetDataSources' is required");}this.resolvedDataSources = new HashMap<>(this.targetDataSources.size());this.targetDataSources.forEach((key, value) -> {Object lookupKey = resolveSpecifiedLookupKey(key);DataSource dataSource = resolveSpecifiedDataSource(value);this.resolvedDataSources.put(lookupKey, dataSource);});if (this.defaultTargetDataSource != null) {//设置解析的默认数据源this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);}}//数据源对应的key，默认和目标数据源map中的key一致protected Object resolveSpecifiedLookupKey(Object lookupKey) {return lookupKey;}//将指定的数据源对象解析为 DataSource 实例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);}}//==========================================获取数据库连接=========================================@Overridepublic Connection getConnection() throws SQLException {return determineTargetDataSource().getConnection();}@Overridepublic Connection getConnection(String username, String password) throws SQLException {//从特定的数据源中获取对应的数据库连接对象return determineTargetDataSource().getConnection(username, password);}protected DataSource determineTargetDataSource() {Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");//DynamicDataSource 中对 determineCurrentLookupKey()方法进行了重写Object lookupKey = determineCurrentLookupKey();//resolvedDataSources 对应的map中获取对应的数据源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;}@Nullableprotected abstract Object determineCurrentLookupKey();}

三. 多数据源 + ShardingJDBC 数据源整合

现有需求: 在多数据源能够动态切换的前提下,其中某个库中的表需要实现分表操作,例如:上述多数据源配置中的second 数据库中某个表需要实现分表操作,我们采用ShardingJDBC实现。此时second 数据源的配置需要更改为ShardingJDBC对应的数据源，如下面更改后的多数据源配置：

原来多数据源配置类

package com.gateway.admin.datasources;import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;/*** 多数据源配置类*/
@Configuration
public class DynamicDataSourceConfig {//如果ioc容器中,同一个类型有多个bean,则bean的名称为方法的名称@Bean@ConfigurationProperties("spring.datasource.druid.first")public DataSource firstDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@ConfigurationProperties("spring.datasource.druid.second")public DataSource secondDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@ConfigurationProperties("spring.datasource.druid.three")public DataSource threeDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@ConfigurationProperties("spring.datasource.druid.four")public DataSource fourDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@Primarypublic DynamicDataSource dataSource(DataSource firstDataSource, DataSource secondDataSource, DataSource threeDataSource, DataSource fourDataSource) {Map<Object, Object> targetDataSources = new HashMap<>();targetDataSources.put(DataSourceNames.FIRST, firstDataSource);targetDataSources.put(DataSourceNames.SECOND, secondDataSource);targetDataSources.put(DataSourceNames.THREE, threeDataSource);targetDataSources.put(DataSourceNames.FOUR, fourDataSource);return new DynamicDataSource(firstDataSource, targetDataSources);}
}

整合ShardingJDBC 后，多数据源配置类

package com.gateway.admin.datasources;
import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import org.apache.shardingsphere.shardingjdbc.jdbc.adapter.AbstractDataSourceAdapter;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Lazy;
import org.springframework.context.annotation.Primary;import javax.annotation.Resource;
import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;/*** 多数据源配置类*/
@Configuration
public class DynamicDataSourceConfig {@Bean@ConfigurationProperties("spring.datasource.druid.first")public DataSource firstDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@ConfigurationProperties("spring.datasource.druid.three")public DataSource threeDataSource() {return DruidDataSourceBuilder.create().build();}@Bean@ConfigurationProperties("spring.datasource.druid.four")public DataSource fourDataSource() {return DruidDataSourceBuilder.create().build();}//该数据源为shardingjdbc对应的数据源,可通过java代码配置,也可通过配置文件配置,此处我们采用yml配置,配置文件下面会给出/*** shardingjdbc有四种数据源，需要根据业务注入不同的数据源** <p>1. 未使用分片, 脱敏的名称(默认): shardingDataSource;* <p>2. 主从数据源: masterSlaveDataSource;* <p>3. 脱敏数据源：encryptDataSource;* <p>4. 影子数据源：shadowDataSource**/@Lazy@Resource(name = "shardingDataSource")private AbstractDataSourceAdapter shardingDataSource;@Bean@Primarypublic DynamicDataSource dataSource(DataSource firstDataSource, DataSource threeDataSource, DataSource fourDataSource) {Map<Object, Object> targetDataSources = new HashMap<>();targetDataSources.put(DataSourceNames.FIRST, firstDataSource);targetDataSources.put(DataSourceNames.SECOND, shardingDataSource);targetDataSources.put(DataSourceNames.THREE, threeDataSource);targetDataSources.put(DataSourceNames.FOUR, fourDataSource);return new DynamicDataSource(firstDataSource, targetDataSources);}
}

对应的yml配置文件为(我们此处只是针对单个库做分表操作):

# Tomcat
server:tomcat:uri-encoding: UTF-8max-threads: 1000min-spare-threads: 30port: 8888spring:#shardingjdbc--------------------------------------------------------------------------------------------------------main:allow-bean-definition-overriding: trueshardingsphere:props:sql:show: truedataSource:names: ds0ds0:type: com.alibaba.druid.pool.DruidDataSourcedriverClassName: com.mysql.jdbc.Driverurl: jdbc:mysql://127.0.0.1:3306/gateway_stable?useUnicode=true&characterEncoding=utf-8&useSSL=falseusername: rootpassword: rootsharding:tables:t_order:logicTable: t_orderactualDataNodes: ds0.t_order$->{1..2}tableStrategy:
#            standard:
#              shardingColumn: id
#              preciseAlgorithmClassName: com.personal.datasources.MonthPreciseShardingAlgorithm
#              rangeAlgorithmClassName:inline:shardingColumn: idalgorithmExpression: t_order$->{id % 2 + 1}keyGenerator:type: SNOWFLAKEcolumn: idworker:id: 1datasource:type: com.alibaba.druid.pool.DruidDataSourcedriverClassName: com.mysql.jdbc.Driverdruid:first:  #数据源1url: jdbc:mysql://172.16.43.43:3306/wanshu_admin?useUnicode=true&characterEncoding=utf-8&useSSL=falseusername: rootpassword: 123456
#      second:  #数据源2
#        url: jdbc:mysql://127.0.0.1:3306/gateway_stable?useUnicode=true&characterEncoding=utf-8&useSSL=false
#        username: root
#        password: rootthree:  #数据源3url: jdbc:mysql://172.16.43.43:3306/datacenter_stable?useUnicode=true&characterEncoding=utf-8&useSSL=falseusername: rootpassword: 123456four:   #数据源4url: jdbc:mysql://172.16.43.43:3306/chuanglan_risk_control?useUnicode=true&characterEncoding=utf-8&useSSL=falseusername: rootpassword: 123456initial-size: 10max-active: 100min-idle: 10max-wait: 60000pool-prepared-statements: truemax-pool-prepared-statement-per-connection-size: 20time-between-eviction-runs-millis: 60000min-evictable-idle-time-millis: 300000validation-query: SELECT 1 FROM DUALtest-while-idle: truetest-on-borrow: falsetest-on-return: falsestat-view-servlet:enabled: trueurl-pattern: /druid/*login-username: adminlogin-password: adminfilter:stat:log-slow-sql: trueslow-sql-millis: 1000merge-sql: falsewall:config:multi-statement-allow: truemybatis:mapper-locations: classpath:mapper/**/*.xml

关于shardingJDBC的相关知识,可参考:shardingJDBC分库分表

相关阅读：dynamic-datasource-spring-boot-starter

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原文链接：https://blog.csdn.net/weixin_43695916/article/details/119210008