SpringBoot+Druid+MyBatis配置多数据源

项目可能会遇到需要对多个数据库进行读写的需求，此时就需要配置多个数据源。

依赖配置

pom.xml配置的依赖如下：

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <!-- alibaba的druid数据库连接池 -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid-spring-boot-starter</artifactId>
    </dependency>
</dependencies>

项目配置

application.yml配置文件内容如下：

spring:
  datasource:
    #使用druid连接池
    type: com.alibaba.druid.pool.DruidDataSource

# 自定义的主数据源配置信息
primary:
  datasource:
    #druid相关配置
    druid:
      #监控统计拦截的filters
      filters: stat
      driverClassName: com.mysql.jdbc.Driver
      #配置基本属性
      url: jdbc:mysql://127.0.0.1:3306/primary_database?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&autoReconnect=true&useSSL=false
      username: root
      password: password
      #配置初始化大小/最小/最大
      initialSize: 1
      minIdle: 1
      maxActive: 20
      #获取连接等待超时时间
      maxWait: 60000
      #间隔多久进行一次检测，检测需要关闭的空闲连接
      timeBetweenEvictionRunsMillis: 60000
      #一个连接在池中最小生存的时间
      minEvictableIdleTimeMillis: 300000
      validationQuery: SELECT 'x'
      testWhileIdle: true
      testOnBorrow: false
      testOnReturn: false
      #打开PSCache，并指定每个连接上PSCache的大小。oracle设为true，mysql设为false。分库分表较多推荐设置为false
      poolPreparedStatements: false
      maxPoolPreparedStatementPerConnectionSize: 20

# 自定义的从数据源配置信息
slave:
  datasource:
    #druid相关配置
    druid:
      #监控统计拦截的filters
      filters: stat
      driverClassName: com.mysql.jdbc.Driver
      #配置基本属性
      url: jdbc:mysql://127.0.0.1:3306/slave_database?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&autoReconnect=true&useSSL=false
      username: root
      password: password
      #配置初始化大小/最小/最大
      initialSize: 1
      minIdle: 1
      maxActive: 20
      #获取连接等待超时时间
      maxWait: 60000
      #间隔多久进行一次检测，检测需要关闭的空闲连接
      timeBetweenEvictionRunsMillis: 60000
      #一个连接在池中最小生存的时间
      minEvictableIdleTimeMillis: 300000
      validationQuery: SELECT 'x'
      testWhileIdle: true
      testOnBorrow: false
      testOnReturn: false
      #打开PSCache，并指定每个连接上PSCache的大小。oracle设为true，mysql设为false。分库分表较多推荐设置为false
      poolPreparedStatements: false
      maxPoolPreparedStatementPerConnectionSize: 20

然后在项目中新建一个config包，并在该包下创建一个PrimaryDataBaseConfig类，作为我们的主数据源配置类，用于加载自定义的主数据源配置信息，以及创建数据源和会话连接工厂等实例：

import com.alibaba.druid.pool.DruidDataSource;
import lombok.Data;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
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 org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;
import java.sql.SQLException;

/**
 * 数据源配置类
 */
@Data
@Configuration
// 前缀为primary.datasource.druid的配置信息
@ConfigurationProperties(prefix = "primary.datasource.druid")
@MapperScan(basePackages = PrimaryDataBaseConfig.PACKAGE, sqlSessionFactoryRef = "primarySqlSessionFactory")
public class PrimaryDataBaseConfig {

    /**
     * dao层的包路径
     */
    static final String PACKAGE = "cn.appblog.mall.dao.primary";

    /**
     * mapper文件的相对路径
     */
    private static final String MAPPER_LOCATION = "classpath:mappers/primary/*.xml";

    private String filters;
    private String url;
    private String username;
    private String password;
    private String driverClassName;
    private int initialSize;
    private int minIdle;
    private int maxActive;
    private long maxWait;
    private long timeBetweenEvictionRunsMillis;
    private long minEvictableIdleTimeMillis;
    private String validationQuery;
    private boolean testWhileIdle;
    private boolean testOnBorrow;
    private boolean testOnReturn;
    private boolean poolPreparedStatements;
    private int maxPoolPreparedStatementPerConnectionSize;

    // 主数据源使用@Primary注解进行标识
    @Primary
    @Bean(name = "primaryDataSource")
    public DataSource primaryDataSource() throws SQLException {
        DruidDataSource druid = new DruidDataSource();
        // 监控统计拦截的filters
        druid.setFilters(filters);

        // 配置基本属性
        druid.setDriverClassName(driverClassName);
        druid.setUsername(username);
        druid.setPassword(password);
        druid.setUrl(url);

        //初始化时建立物理连接的个数
        druid.setInitialSize(initialSize);
        //最大连接池数量
        druid.setMaxActive(maxActive);
        //最小连接池数量
        druid.setMinIdle(minIdle);
        //获取连接时最大等待时间，单位毫秒。
        druid.setMaxWait(maxWait);
        //间隔多久进行一次检测，检测需要关闭的空闲连接
        druid.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        //一个连接在池中最小生存的时间
        druid.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        //用来检测连接是否有效的sql
        druid.setValidationQuery(validationQuery);
        //建议配置为true，不影响性能，并且保证安全性。
        druid.setTestWhileIdle(testWhileIdle);
        //申请连接时执行validationQuery检测连接是否有效
        druid.setTestOnBorrow(testOnBorrow);
        druid.setTestOnReturn(testOnReturn);
        //是否缓存preparedStatement，也就是PSCache，oracle设为true，mysql设为false。分库分表较多推荐设置为false
        druid.setPoolPreparedStatements(poolPreparedStatements);
        // 打开PSCache时，指定每个连接上PSCache的大小
        druid.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);

        return druid;
    }

    // 创建该数据源的事务管理
    @Primary
    @Bean(name = "primaryTransactionManager")
    public DataSourceTransactionManager primaryTransactionManager() throws SQLException {
        return new DataSourceTransactionManager(primaryDataSource());
    }

    // 创建Mybatis的连接会话工厂实例
    @Primary
    @Bean(name = "primarySqlSessionFactory")
    public SqlSessionFactory primarySqlSessionFactory(@Qualifier("primaryDataSource") DataSource primaryDataSource) throws Exception {
        final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
        sessionFactory.setDataSource(primaryDataSource);  // 设置数据源bean
        sessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources(PrimaryDataBaseConfig.MAPPER_LOCATION));  // 设置mapper文件路径

        return sessionFactory.getObject();
    }
}

同样的，还需要创建一个从数据源配置类，与主数据源配置类不同的是，从数据源配置类不能使用@Primary注解，即表示它是一个从数据源。代码如下：

import com.alibaba.druid.pool.DruidDataSource;
import lombok.Data;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;
import java.sql.SQLException;

/**
 * 后台数据源配置类
 */
@Data
@Configuration
@ConfigurationProperties(prefix = "slave.datasource.druid")
@MapperScan(basePackages = SlaveDataBaseConfig.PACKAGE, sqlSessionFactoryRef = "slaveSqlSessionFactory")
public class SlaveDataBaseConfig {

    /**
     * dao层的包路径
     */
    static final String PACKAGE = "cn.appblog.mall.dao.slave";

    /**
     * mapper文件的相对路径
     */
    private static final String MAPPER_LOCATION = "classpath:mappers/slave/*.xml";

    private String filters;
    private String url;
    private String username;
    private String password;
    private String driverClassName;
    private int initialSize;
    private int minIdle;
    private int maxActive;
    private long maxWait;
    private long timeBetweenEvictionRunsMillis;
    private long minEvictableIdleTimeMillis;
    private String validationQuery;
    private boolean testWhileIdle;
    private boolean testOnBorrow;
    private boolean testOnReturn;
    private boolean poolPreparedStatements;
    private int maxPoolPreparedStatementPerConnectionSize;

    @Bean(name = "slaveDataSource")
    public DataSource slaveDataSource() throws SQLException {
        DruidDataSource druid = new DruidDataSource();
        // 监控统计拦截的filters
        druid.setFilters(filters);

        // 配置基本属性
        druid.setDriverClassName(driverClassName);
        druid.setUsername(username);
        druid.setPassword(password);
        druid.setUrl(url);

        //初始化时建立物理连接的个数
        druid.setInitialSize(initialSize);
        //最大连接池数量
        druid.setMaxActive(maxActive);
        //最小连接池数量
        druid.setMinIdle(minIdle);
        //获取连接时最大等待时间，单位毫秒。
        druid.setMaxWait(maxWait);
        //间隔多久进行一次检测，检测需要关闭的空闲连接
        druid.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        //一个连接在池中最小生存的时间
        druid.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        //用来检测连接是否有效的sql
        druid.setValidationQuery(validationQuery);
        //建议配置为true，不影响性能，并且保证安全性。
        druid.setTestWhileIdle(testWhileIdle);
        //申请连接时执行validationQuery检测连接是否有效
        druid.setTestOnBorrow(testOnBorrow);
        druid.setTestOnReturn(testOnReturn);
        //是否缓存preparedStatement，也就是PSCache，oracle设为true，mysql设为false。分库分表较多推荐设置为false
        druid.setPoolPreparedStatements(poolPreparedStatements);
        // 打开PSCache时，指定每个连接上PSCache的大小
        druid.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);

        return druid;
    }

    @Bean(name = "backTransactionManager")
    public DataSourceTransactionManager backTransactionManager() throws SQLException {
        return new DataSourceTransactionManager(slaveDataSource());
    }

    @Bean(name = "slaveSqlSessionFactory")
    public SqlSessionFactory slaveSqlSessionFactory(@Qualifier("slaveDataSource") DataSource slaveDataSource) throws Exception {
        final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
        sessionFactory.setDataSource(slaveDataSource);
        sessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources(BackDataBaseConfig.MAPPER_LOCATION));

        return sessionFactory.getObject();
    }
}

完成以上配置后，该工程即具有连接两个数据库的能力，如果要配置两个以上的数据库也是一样的，配置多个从数据源即可。