背景

最近让我做一个大数据的系统，分析了一下，麻烦的地方就是多数据源切换抽取数据。考虑到可以跨服务器跨数据库抽数，再整理数据，就配置了这个动态数据源的解决方案。在此分享给大家。

实现方案

数据库配置文件

我们项目使用的是yml形式的配置文件，采用的是hikari的数据库连接池。第一步我们自然是配置多个数据库源头。
我们找到spring的datasource，在下方配置三个数据源。

spring:
  application:
    name: dynamicDatasource
  datasource:
    test1:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://127.0.0.1:3306/test1?serverTimezone=GMT%2B8&characterEncoding=utf-8&useSSL=false
      username: root
      password: 123456
    test2:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://127.0.0.1:3306/test2?serverTimezone=GMT%2B8&characterEncoding=utf-8&useSSL=false
      username: root
      password: 123456
    test3:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://127.0.0.1:3306/test3?serverTimezone=GMT%2B8&characterEncoding=utf-8&useSSL=false
      username: root
      password: 123456
    hikari:
      leak-detection-threshold: 2000

定义数据源实体类

我们可以建立个datasourceBean文件夹专门管理数据源的实体类。
我们这里要建立三个实体类。分别对应test1，test2，test3

@Configuration
public class Test1DataSourceBean {

    @Value("${spring.datasource.test1.driver-class-name}")
    private String test1Driver;

    @Value("${spring.datasource.test1.url}")
    private String test1Url;

    @Value("${spring.datasource.test1.username}")
    private String test1Username;

    @Value("${spring.datasource.test1.password}")
    private String test1Password;

    @Bean(name="test1DataSource")
    public DataSource test1DataSource() throws Exception{
        HikariDataSource dataSource = new HikariDataSource();
        dataSource.setDriverClassName(test1Driver);
        dataSource.setJdbcUrl(test1Url);
        dataSource.setUsername(test1Username);
        dataSource.setPassword(test1Password);
        return dataSource;
    }
}

@Configuration
public class Test2DataSourceBean {

    @Value("${spring.datasource.test2.driver-class-name}")
    private String test2Driver;

    @Value("${spring.datasource.test2.url}")
    private String test2Url;

    @Value("${spring.datasource.test2.username}")
    private String test2Username;

    @Value("${spring.datasource.test2.password}")
    private String test2Password;

    @Bean(name="test2DataSource")
    public DataSource test2DataSource() throws Exception{
        HikariDataSource dataSource = new HikariDataSource();
        dataSource.setDriverClassName(test2Driver);
        dataSource.setJdbcUrl(test2Url);
        dataSource.setUsername(test2Username);
        dataSource.setPassword(test2Password);
        return dataSource;
    }
}

@Configuration
public class Test3DataSourceBean {

    @Value("${spring.datasource.test3.driver-class-name}")
    private String test3Driver;

    @Value("${spring.datasource.test3.url}")
    private String test3Url;

    @Value("${spring.datasource.test3.username}")
    private String test3Username;

    @Value("${spring.datasource.test3.password}")
    private String test3Password;

    @Bean(name="test3DataSource")
    public DataSource test3DataSource() throws Exception{
        HikariDataSource dataSource = new HikariDataSource();
        dataSource.setDriverClassName(test3Driver);
        dataSource.setJdbcUrl(test3Url);
        dataSource.setUsername(test3Username);
        dataSource.setPassword(test3Password);
        return dataSource;
    }
}

定义一个枚举类管理数据源

public enum DatabaseType {

    test1("test1", "test1"),
    test2("test2", "test2"),
    test3("test3","test3");

    private String name;
    private String value;

    DatabaseType(String name, String value){
        this.name = name;
        this.value = value;
    }

    public String getName(){
        return name;
    }

    public String getValue(){
        return value;
    }
}

定义一个线程安全的数据源容器

public class DatabaseContextHolder {

    private static final ThreadLocal<DatabaseType> contextHolder = new ThreadLocal<>();

    public static void setDatabaseType(DatabaseType type){
        contextHolder.set(type);
    }

    public static DatabaseType getDatabaseType(){
        return contextHolder.get();
    }
}

定义动态数据源

public class DynamicDataSource extends AbstractRoutingDataSource{

    protected Object determineCurrentLookupKey() {
        return DatabaseContextHolder.getDatabaseType();
    }
}

mybatis配置类

网上的很多文章配置出来都会产生数据源循环依赖的问题，这里解决了这个问题。

@Configuration
@MapperScan(basePackages="cn.test.jichi", sqlSessionFactoryRef="sessionFactory")
public class MybatisConfig {

    /**
     *  @Description:设置动态数据源
     */
    @Bean(name="dynamicDataSource")
    @Primary
    public DynamicDataSource DataSource(
            @Qualifier("test1DataSource") DataSource test1DataSource,
            @Qualifier("test2DataSource") DataSource test2DataSource,
            @Qualifier("test3DataSource") DataSource test3DataSource){
        Map<Object, Object> targetDataSource = new HashMap<>();
        targetDataSource.put(DatabaseType.test1, test1DataSource);
        targetDataSource.put(DatabaseType.test2, test2DataSource);
        targetDataSource.put(DatabaseType.test3, test3DataSource);
        DynamicDataSource dataSource = new DynamicDataSource();
        dataSource.setTargetDataSources(targetDataSource);
        dataSource.setDefaultTargetDataSource(test1DataSource);
        return dataSource;
    }

    /**
     *  @Description:根据动态数据源创建sessionFactory
     */
    @Bean(name="sessionFactory")
    public SqlSessionFactory sessionFactory(
            @Qualifier("test1DataSource") DataSource test1DataSource,
            @Qualifier("test2DataSource") DataSource test2DataSource,
            @Qualifier("test3DataSource") DataSource test3DataSource) throws Exception{
        SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
        //构造方法，解决动态数据源循环依赖问题。
        sessionFactoryBean.setDataSource(this.DataSource(test1DataSource,test2DataSource, test3DataSource));
        return sessionFactoryBean.getObject();
    }
}

package cn.chinaunicom.sdsi.utils;

import cn.chinaunicom.sdsi.config.dynamicDataSourceConfig.DatabaseContextHolder;
import cn.chinaunicom.sdsi.config.dynamicDataSourceConfig.DatabaseType;

/**
 *  @Description:封装数据源选择
 */
public class DynamicDataSourceUtils {

    public static void chooseBasicDataSource(){
        DatabaseContextHolder.setDatabaseType(DatabaseType.basic);
    }

    public static void chooseBranchDataSource(){
        DatabaseContextHolder.setDatabaseType(DatabaseType.branch);
    }

}

提供一个示例

    public void testDymnaicDatasource(){
        //不切换数据源默认是自己的。
        System.out.println("-----默认数据源");
        DemoEntity totalCount = demoMapper.getTotalCount();
        String nameCount1 = totalCount.getNameCount();
        String ageCount2 = totalCount.getAgeCount();
        System.out.println("nameCount:"+nameCount1);
        System.out.println("ageCount:"+ageCount2);
        //数据源切换为branch
        System.out.println("-----数据源为test2");
        DynamicDataSourceUtils.chooseBranchDataSource();
        Integer nameCount = demoMapper.getNameCount();
        Integer ageCount = demoMapper.getAgeCount();
        System.out.println("nameCount:"+nameCount);
        System.out.println("ageCount:"+ageCount);
        //数据源为basic
        System.out.println("-----数据源为test3");
        DynamicDataSourceUtils.chooseBasicDataSource();
        Integer ageCount1 = demoMapper.getAgeCount();
        System.out.println("ageCount:"+ageCount1);

    }

总结

至此实现了多数据源的动态切换。可以在同一个方法里面进行操作多个数据源。