<select

  id="selectPerson"

  parameterType="int"

  parameterMap="deprecated"

  resultType="hashmap"

  resultMap="personResultMap"

  flushCache="false"

  useCache="true"

  timeout="10000"

  fetchSize="256"

  statementType="PREPARED"

  resultSetType="FORWARD_ONLY"

  databaseId="mysql">

<databaseIdProvider type="DB_VENDOR">

　　<property name="MySQL" value="mysql" />

   <property name="Oracle" value="oracle" />

</databaseIdProvider>

public interface DatabaseIdProviderMapper {

    String selectTime();

}

<mapper namespace="com.yihaomen.mybatis.dao.DatabaseIdProviderMapper">

    <select id="selectTime" resultType="String" databaseId="mysql">

        SELECT NOW() FROM dual

    </select>

    <select id="selectTime" resultType="String" databaseId="oracle">

        SELECT  'oralce'||to_char(sysdate,'yyyy-mm-dd hh24:mi:ss')  FROM dual

    </select>

</mapper>

<mappers>

    <mapper resource="com/yihaomen/mybatis/model/DatabaseIdProvider.xml"/>

</mappers>

jdbc.driver=com.mysql.jdbc.Driver

jdbc.url=jdbc:mysql://127.0.0.1:3306/mybatis-learn?characterEncoding=utf8

jdbc.username=root

jdbc.password=tiger

#jdbc.driver=oracle.jdbc.driver.OracleDriver

#jdbc.url=jdbc:oracle:thin:@localhost:1521:mybatis

#jdbc.username=mybatis

#jdbc.password=mybatis

maxActive= 50

import com.yihaomen.mybatis.dao.DatabaseIdProviderMapper;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import user.BaseTest;

public class DatabaseIdProviderTest extends BaseTest{

    public static void main(String[] args) {

        SqlSessionFactory factory = getSession();

        SqlSession session = factory.openSession();

        DatabaseIdProviderMapper mapper = session.getMapper(DatabaseIdProviderMapper.class);

        System.out.println(mapper.selectTime());

    }

}