mybatis使用小贴士

SqlSession session = getSqlSession();
int sqlResult = session.insert("insert a table", po);
int sqlResult = session.update("update b table", po);
//这时，前面的insert和update还没真正执行
session.commit();
//commit后，db才真正更新
session.close();

     <sql id="getFeedBackList_fragment">
from t_comment where refer_type = #{type} and
refer_id = #{referId} 
     </sql>

<select id=‘getFeedBackList‘ parameterType=‘map‘ resultMap=‘feeback‘>
select id
<include refid="getFeedBackList_fragment"/>
order by
create_time desc
</select>

<configuration>
 ……

<typeHandlers>
<typeHandler handler="test.TimeTypeHandler"
javaType="Long" jdbcType="TIME" />
</typeHandlers>
……
</configuration>

package test;
public class TimeTypeHandler implements TypeHandler<Long>
{
private final String TIME_TYPE = "yyyy-MM-dd HH:mm:ss";

public long strToLongTime(String dateStr)
{
if (null == dateStr)
return 0L;

SimpleDateFormat sdf = new SimpleDateFormat(TIME_TYPE);
Date date = new Date();
try
{
date = sdf.parse(dateStr);
}
catch (ParseException e)
{
e.printStackTrace();
}
if (date == null)
return 0L;

System.out.println(date);
return date.getTime();
}

public Long getResult(ResultSet arg0, String arg1) throws SQLException
{
String datestr = arg0.getString(arg1);
return strToLongTime(datestr);
}

public Long getResult(ResultSet arg0, int arg1) throws SQLException
{
String datestr = arg0.getString(arg1);
return strToLongTime(datestr);
}

public Long getResult(CallableStatement arg0, int arg1) throws SQLException
{
String datestr = arg0.getString(arg1);
return strToLongTime(datestr);
}

public void setParameter(PreparedStatement arg0, int arg1, Long arg2, JdbcType arg3) throws SQLException
{
if (arg2 == null)
{
arg2 = 0L;
}

Date date = new Date(arg2);
SimpleDateFormat sdf = new SimpleDateFormat(TIME_TYPE);
String datetime = sdf.format(date);
arg0.setString(arg1, datetime);
}

}

<mapper namespace="xxxx">
……
     //这里定义了ExpDownloadPo这个sql查询结果，要映射到java bean ：test.ExpDownloadPo
<resultMap id="ExpDownloadPo"  type="test.ExpDownloadPo">
<id property="id" column="id" />
               //first_download_time这个数据，在赋值到firstDownloadTime时，要转转换，从jdbc的time型，转换成javaType的long型，具体怎么转换，因为前面第一点，定义了<typeHandlers><typeHandler handler="test.TimeTypeHandler" javaType="Long" jdbcType="TIME" /></typeHandlers>，因此会自动使用test.TimeTypeHandler这个转换器

<result property="firstDownloadTime" column="first_download_time" javaType="Long" jdbcType="TIME"/>
<result property="lastDownloadTime" column="last_download_time" javaType="Long" jdbcType="TIME"/>
</resultMap>
……
</mapper >

<mapper namespace="com.blog.test">
……
<resultMap id="testbean"  ></resultMap>
</mapper>

<mapper namespace="B">
<select id="mysql" parameterType="map" resultMap="com.blog.test.testbean">
</mapper>