Spring Boot 动态数据源示例（多数据源自动切换）

本文实现案例场景：

某系统除了需要从自己的主要数据库上读取和管理数据外，还有一部分业务涉及到其他多个数据库，要求可以在任何方法上可以灵活指定具体要操作的数据库。

为了在开发中以最简单的方法使用，本文基于注解和AOP的方法实现，在spring boot框架的项目中，添加本文实现的代码类后，只需要配置好数据源就可以直接通过注解使用，简单方便。

一配置二使用

1. 启动类注册动态数据源

2. 配置文件中配置多个数据源

3. 在需要的方法上使用注解指定数据源

1、在启动类添加 @import({DynamicDataSourceRegister.class, MProxyTransactionManagementConfiguration.class})

@SpringBootApplication
@import({DynamicDataSourceRegister.class}) // 注册动态多数据源
public class SpringBootSampleApplication {

  // 省略其他代码
}

2、配置文件配置内容为：（不包括项目中的其他配置，这里只是数据源相关的）

# 主数据源，默认的
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=123456

# 更多数据源
custom.datasource.names=ds1,ds2
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=123456

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=123456

3、使用方法

package org.springboot.sample.service;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import org.springboot.sample.datasource.TargetDataSource;
import org.springboot.sample.entity.Student;
import org.springboot.sample.mapper.StudentMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Service;


@Service
public class StudentService {

  @Autowired
  private JdbcTemplate jdbcTemplate;

  // MyBatis的Mapper方法定义接口
  @Autowired
  private StudentMapper studentMapper;

  @TargetDataSource(name="ds2")
  public List likeName(String name){
    return studentMapper.likeName(name);
  }

  public List likeNameByDefaultDataSource(String name){
    return studentMapper.likeName(name);
  }

  
  public List getList(){
    String sql = "SELECt ID,NAME,SCORE_SUM,SCORE_AVG, AGE  FROM STUDENT";
    return (List) jdbcTemplate.query(sql, new RowMapper(){

      @Override
      public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
 Student stu = new Student();
 stu.setId(rs.getInt("ID"));
 stu.setAge(rs.getInt("AGE"));
 stu.setName(rs.getString("NAME"));
 stu.setSumScore(rs.getString("SCORE_SUM"));
 stu.setAvgScore(rs.getString("SCORE_AVG"));
 return stu;
      }

    });
  }

  
  @TargetDataSource(name="ds1")
  public List getListByDs1(){
    String sql = "SELECt ID,NAME,SCORE_SUM,SCORE_AVG, AGE  FROM STUDENT";
    return (List) jdbcTemplate.query(sql, new RowMapper(){

      @Override
      public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
 Student stu = new Student();
 stu.setId(rs.getInt("ID"));
 stu.setAge(rs.getInt("AGE"));
 stu.setName(rs.getString("NAME"));
 stu.setSumScore(rs.getString("SCORE_SUM"));
 stu.setAvgScore(rs.getString("SCORE_AVG"));
 return stu;
      }

    });
  }

  
  @TargetDataSource(name="ds2")
  public List getListByDs2(){
    String sql = "SELECt ID,NAME,SCORE_SUM,SCORE_AVG, AGE  FROM STUDENT";
    return (List) jdbcTemplate.query(sql, new RowMapper(){

      @Override
      public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
 Student stu = new Student();
 stu.setId(rs.getInt("ID"));
 stu.setAge(rs.getInt("AGE"));
 stu.setName(rs.getString("NAME"));
 stu.setSumScore(rs.getString("SCORE_SUM"));
 stu.setAvgScore(rs.getString("SCORE_AVG"));
 return stu;
      }

    });
  }
}

要注意的是，在使用MyBatis时，注解@TargetDataSource 不能直接在接口类Mapper上使用。

按上面的代码中StudentMapper为接口，代码如下：

package org.springboot.sample.mapper;

import java.util.List;

import org.springboot.sample.entity.Student;


public interface StudentMapper {

  // 注解 @TargetDataSource 不可以在这里使用
  List likeName(String name);

  Student getById(int id);

  String getNameById(int id);

}

请将下面几个类放到Spring Boot项目中。

DynamicDataSource.Java

DynamicDataSourceAspect.java

DynamicDataSourceContextHolder.java

DynamicDataSourceRegister.java

TargetDataSource.java

package org.springboot.sample.datasource;

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;


public class DynamicDataSource extends AbstractRoutingDataSource {

  @Override
  protected Object determineCurrentLookupKey() {
    return DynamicDataSourceContextHolder.getDataSourceType();
  }

}

package org.springboot.sample.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.stereotype.Component;


@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 : {} > {}", ds.name(), point.getSignature());
      DynamicDataSourceContextHolder.setDataSourceType(ds.name());
    }
  }

  @After("@annotation(ds)")
  public void restoreDataSource(JoinPoint point, TargetDataSource ds) {
    logger.debug("Revert DataSource : {} > {}", ds.name(), point.getSignature());
    DynamicDataSourceContextHolder.clearDataSourceType();
  }

}

package org.springboot.sample.datasource;

import java.util.ArrayList;
import java.util.List;

public class DynamicDataSourceContextHolder {

  private static final ThreadLocal contextHolder = new ThreadLocal();
  public static List 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();
  }

  
  public static boolean containsDataSource(String dataSourceId){
    return dataSourceIds.contains(dataSourceId);
  }
}

package org.springboot.sample.datasource;

import java.util.HashMap;
import java.util.Map;

import javax.sql.DataSource;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.PropertyValues;
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;


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 = "org.apache.tomcat.jdbc.pool.DataSource";
  // private static final Object DATASOURCE_TYPE_DEFAULT =
  // "com.zaxxer.hikari.HikariDataSource";

  // 数据源
  private DataSource defaultDataSource;
  private Map customDataSources = new HashMap<>();

  @Override
  public void registerBeanDefinitions(Annotationmetadata importingClassmetadata, BeanDefinitionRegistry registry) {
    Map targetDataSources = new HashMap();
    // 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");
  }

  
  @SuppressWarnings("unchecked")
  public DataSource buildDataSource(Map dsMap) {
    try {
      Object type = dsMap.get("type");
      if (type == null)
 type = DATASOURCE_TYPE_DEFAULT;// 默认DataSource

      Class dataSourceType;
      dataSourceType = (Class) 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;
  }

  
  @Override
  public void setEnvironment(Environment env) {
    initDefaultDataSource(env);
    initCustomDataSources(env);
  }

  
  private void initDefaultDataSource(Environment env) {
    // 读取主数据源
    RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(env, "spring.datasource.");
    Map 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);

    dataBinder(defaultDataSource, env);
  }

  
  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 rpr = new RelaxedPropertyResolver(env, "spring.datasource").getSubProperties(".");
      Map values = new HashMap<>(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);
  }

  
  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, "custom.datasource.");
    String dsPrefixs = propertyResolver.getProperty("names");
    for (String dsPrefix : dsPrefixs.split(",")) {// 多个数据源
      Map dsMap = propertyResolver.getSubProperties(dsPrefix + ".");
      DataSource ds = buildDataSource(dsMap);
      customDataSources.put(dsPrefix, ds);
      dataBinder(ds, env);
    }
  }

}

package org.springboot.sample.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;


@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@documented
public @interface TargetDataSource {
  String name();
}

本文代码博主是经过测试后没有问题才发出来共享给大家的。对于连接池参数配置会应用到所有数据源上。
比如配置一个：

spring.datasource.maximum-pool-size=80

那么我们所有的数据源都会自动应用上。

补充：

如果你使用的是SpringMVC，并集成了Shiro，一般按网上的配置你可能是：

那么你请不要这样做，请按下面方法配置：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。

Spring Boot 动态数据源示例（多数据源自动切换）

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