custom.datasource.defaultname=default
custom.datasource.names=ds1,ds2
 
# 默认数据源
custom.datasource.driver-class-name=com.mysql.jdbc.Driver
custom.datasource.url=jdbc:mysql://localhost:3306/test
custom.datasource.username=root
custom.datasource.password=root
 
# 更多数据源
custom.datasource.ds1.driver-class-name=com.mysql.jdbc.Driver
custom.datasource.ds1.url=jdbc:mysql://localhost:3306/test1
custom.datasource.ds1.username=root
custom.datasource.ds1.password=root
 
custom.datasource.ds2.driver-class-name=com.mysql.jdbc.Driver
custom.datasource.ds2.url=jdbc:mysql://localhost:3306/test2
custom.datasource.ds2.username=root
custom.datasource.ds2.password=root
 
 
custom.datasource.filters=stat
custom.datasource.maxActive=100
custom.datasource.initialSize=1
custom.datasource.minIdle=1
custom.datasource.timeBetweenEvictionRunsMillis=60000
custom.datasource.minEvictableIdleTimeMillis=300000
custom.datasource.validationQuery=select \'x\'
custom.datasource.testWhileIdle=true
custom.datasource.testOnBorrow=false
custom.datasource.testOnReturn=false
custom.datasource.poolPreparedStatements=true
custom.datasource.maxOpenPreparedStatements=100
 
mybatis.type-aliases-package=com.example.demo.model.*
mybatis.mapper-locations=classpath:mapper/**/*.xml

DynamicDataSource：动态数据源切换；
DynamicDataSourceAspect：利用AOP切面实现数据源的动态切换；
DynamicDataSourceContextHolder：动态切换数据源；
DynamicDataSourceRegister：动态数据源注册；
TargetDataSource：在方法上使用，用于指定使用哪个数据源。

package com.example.demo.datasource;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
 
/**
 * 动态数据源
 */
public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        return DynamicDataSourceContextHolder.getDataSourceType();
    }
}

package com.example.demo.datasource;
 
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.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
 
/**
 * 切换数据源Advice
 */
@Aspect
@Order(-1)// 保证该AOP在@Transactional之前执行
@Component
public class DynamicDataSourceAspect {
    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);
 
    @Before("@annotation(ds)")
    public void changeDataSource(JoinPoint point, TargetDataSource ds) throws Throwable {
        String dsId = ds.name();
        if (!DynamicDataSourceContextHolder.containsDataSource(dsId)) {
            logger.error("数据源[{}]不存在，使用默认数据源 > {}", ds.name(), point.getSignature());
        }else {
            logger.debug("Use DataSource : {} > {}", dsId, point.getSignature());
            DynamicDataSourceContextHolder.setDataSourceType(dsId);
        }
 
    }
    @After("@annotation(ds)")
    public void restoreDataSource(JoinPoint point, TargetDataSource ds) {
        logger.debug("Revert DataSource : {} > {}", ds.name(), point.getSignature());
        DynamicDataSourceContextHolder.clearDataSourceType();
    }
}

package com.example.demo.datasource;
 
import java.util.ArrayList;
import java.util.List;
 
public class DynamicDataSourceContextHolder {
    private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();
    public static List<String> dataSourceIds = new ArrayList<>();
 
    public static void setDataSourceType(String dataSourceType) {
        contextHolder.set(dataSourceType);
    }
 
    public static String getDataSourceType() {
        return contextHolder.get();
    }
 
    public static void clearDataSourceType() {
        contextHolder.remove();
    }
 
    /**
     * 判断指定DataSrouce当前是否存在
     */
    public static boolean containsDataSource(String dataSourceId){
        return dataSourceIds.contains(dataSourceId);
    }
}

package com.example.demo.datasource;
 
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.bind.RelaxedDataBinder;
import org.springframework.boot.bind.RelaxedPropertyResolver;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.DefaultConversionService;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotationMetadata;
 
import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;
 
/**
 *  动态数据源注册
 *  启动动态数据源请在启动类中 添加 @Import(DynamicDataSourceRegister.class)
 */
public class DynamicDataSourceRegister
        implements ImportBeanDefinitionRegistrar, EnvironmentAware {
 
    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceRegister.class);
    private ConversionService conversionService = new DefaultConversionService();
    private PropertyValues dataSourcePropertyValues;
 
    // 如配置文件中未指定数据源类型，使用该默认值
    private static final Object DATASOURCE_TYPE_DEFAULT = "com.alibaba.druid.pool.DruidDataSource";
 
    // 数据源
    private DataSource defaultDataSource;
    private Map<String, DataSource> customDataSources = new HashMap<>();
 
    private static String DB_NAME = "names";
    private static String DB_DEFAULT_VALUE = "custom.datasource"; //配置文件中前缀
    @Value("${bi.datasource.defaultname}")
    private String defaultDbname;
 
    //加载多数据源配置
    @Override
    public void setEnvironment(Environment env) {
        initDefaultDataSource(env);
        initCustomDataSources(env);
    }
 
    //初始化主数据源
    private void initDefaultDataSource(Environment env) {
        // 读取主数据源
        RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(env, DB_DEFAULT_VALUE+".");
        Map<String, Object> dsMap = new HashMap<>();
        dsMap.put("type", propertyResolver.getProperty("type"));
        dsMap.put("driver-class-name", propertyResolver.getProperty("driver-class-name"));
        dsMap.put("url", propertyResolver.getProperty("url"));
        dsMap.put("username", propertyResolver.getProperty("username"));
        dsMap.put("password", propertyResolver.getProperty("password"));
 
        defaultDataSource = buildDataSource(dsMap);
        customDataSources.put(defaultDbname,defaultDataSource);//默认数据源放到动态数据源里
        dataBinder(defaultDataSource, env);
    }
 
 
    //为DataSource绑定更多数据
    private void dataBinder(DataSource dataSource, Environment env) {
        RelaxedDataBinder dataBinder = new RelaxedDataBinder(dataSource);
        //dataBinder.setValidator(new LocalValidatorFactory().run(this.applicationContext));
        dataBinder.setConversionService(conversionService);
        dataBinder.setIgnoreNestedProperties(false);//false
        dataBinder.setIgnoreInvalidFields(false);//false
        dataBinder.setIgnoreUnknownFields(true);//true
        if (dataSourcePropertyValues == null) {
            Map<String, Object> rpr = new RelaxedPropertyResolver(env, DB_DEFAULT_VALUE).getSubProperties(".");
            Map<String, Object> values = new HashMap<String, Object>(rpr);
            // 排除已经设置的属性
            values.remove("type");
            values.remove("driver-class-name");
            values.remove("url");
            values.remove("username");
            values.remove("password");
            dataSourcePropertyValues = new MutablePropertyValues(values);
        }
        dataBinder.bind(dataSourcePropertyValues);
    }
 
    //初始化更多数据源
    private void initCustomDataSources(Environment env) {
        // 读取配置文件获取更多数据源，也可以通过defaultDataSource读取数据库获取更多数据源
        RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(env,DB_DEFAULT_VALUE+".");
        String dsPrefixs = propertyResolver.getProperty(DB_NAME);
        for (String dsPrefix : dsPrefixs.split(",")) {// 多个数据源
            Map<String, Object> dsMap = propertyResolver.getSubProperties(dsPrefix + ".");
            DataSource ds = buildDataSource(dsMap);
            customDataSources.put(dsPrefix, ds);
            dataBinder(ds, env);
        }
    }
 
    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        Map<Object, Object> targetDataSources = new HashMap<Object, Object>();
        // 将主数据源添加到更多数据源中
        targetDataSources.put("dataSource", defaultDataSource);
        DynamicDataSourceContextHolder.dataSourceIds.add("dataSource");
        // 添加更多数据源
        targetDataSources.putAll(customDataSources);
        for (String key : customDataSources.keySet()) {
            DynamicDataSourceContextHolder.dataSourceIds.add(key);
        }
 
        // 创建DynamicDataSource
        GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
        beanDefinition.setBeanClass(DynamicDataSource.class);
        beanDefinition.setSynthetic(true);
        MutablePropertyValues mpv = beanDefinition.getPropertyValues();
        mpv.addPropertyValue("defaultTargetDataSource", defaultDataSource);
        mpv.addPropertyValue("targetDataSources", targetDataSources);
        registry.registerBeanDefinition("dataSource", beanDefinition);
 
        logger.info("Dynamic DataSource Registry");
    }
 
    //创建DataSource
    @SuppressWarnings("unchecked")
    public DataSource buildDataSource(Map<String, Object> dsMap) {
        try {
            Object type = dsMap.get("type");
            if (type == null)
                type = DATASOURCE_TYPE_DEFAULT;// 默认DataSource
 
            Class<? extends DataSource> dataSourceType;
            dataSourceType = (Class<? extends DataSource>) Class.forName((String) type);
 
            String driverClassName = dsMap.get("driver-class-name").toString();
            String url = dsMap.get("url").toString();
            String username = dsMap.get("username").toString();
            String password = dsMap.get("password").toString();
 
            DataSourceBuilder factory = DataSourceBuilder.create().driverClassName(driverClassName).url(url)
                    .username(username).password(password).type(dataSourceType);
            return factory.build();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }
}

package com.example.demo.datasource;
 
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;
 
// 在方法上使用，用于指定使用哪个数据源
@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TargetDataSource {
    String name();
}