mybatis用法總結

一.設置的resutType爲Integer/Double類時

此時java接收的對象便可以是單個對象,也能夠是List對象,具體以下:

//dao文件
List<Integer> selectNotTest();
Double selMaxRetracement(@Param(value = "account") Integer account);

//xml文件
<!--查詢非test帳號集合-->
<select id="selectNotTest" resultType="Integer">
    select distinct(account) from mt4list_rel
</select>
<!--查詢帳號得最大回撤值-->
<select id="selMaxRetracement" resultType="Double">
    select MaxRetracement from retracement_index where Account=#{account}
</select>

二.設置的resultType爲hashmap時設置

此時mapper文件中設置的resultType爲hashmap,java中具體接收的是Map,同時返回的數據中,key爲select語句中設置的別名,value爲計算的數值,好比:下面的語句中,map中的一個key-value會是以下:key--allOrderNum,value--count(*)計算出來的數值

//dao文件
Map<String,Object> selectAccountDeatail(@Param(value = "account")String table);

//xml文件
<!--查詢帳戶的總訂單數,總手數,平倉總盈虧,平均手數-->
<select id="selectAccountDeatail" resultType="hashmap">
    select count(*) as allOrderNum,sum(Volume) as allVolumes,sum(profit) as historyProfit,sum(Volume)/count(*) as avgVolume from ${account} where cmd in ('buy','sell')
</select>

三.返回實體類得時候封裝成resultMap

resultType與resultMap只能存在一個,用resultMap將數據庫的字段與實體類進行匹配,而後返回的一個List,同事List中的中的元素爲數據庫表對應的實體類,具體以下:

//dao文件
List<CloseOrder> queryCloseOrderByAccount(@Param(value = "list") String[] list);

//xml文件
<resultMap id="CloseOrderResultMap" type="com.kflh.boxApi.apiNoCheckWestffs.entity.CloseOrder">
    <id column="id" property="id"/>
    <result column="closeorder" property="closeOrder"/>
    <result column="account" property="account"/>
    <result column="symbol" property="symbol"/>
    <result column="cmd" property="cmd"/>
    <result column="Volume" property="volume"/>
    <result column="OpenTime" property="openTime"/>
    <result column="OpenPrice" property="openPrice"/>
    <result column="SL" property="sl"/>
    <result column="TP" property="tp"/>
    <result column="Magic" property="magic"/>
    <result column="Comment" property="comment"/>
    <result column="timestamp" property="timestamp"/>
</resultMap>

<select id="queryCloseOrderByAccount" resultMap="CloseOrderResultMap">
  select * from closeorder where account in
    <foreach item="item" index="index" collection="list"
             open="(" separator="," close=")">
        #{item}
    </foreach>
</select>

四.當須要根據某個字段分組並將分組數據返回的時候

具體用法參照以下連接
https://www.cnblogs.com/eternityz/p/12284808.html

//dao文件
List<CloseOrderList> selectCloseOrderList();

<resultMap id="customResultMap" type="com.kflh.boxApi.chooseSignalSource.entity.CloseOrderList">
    <id property="account" column="account"/>
    <collection property="closeOrderList" ofType="com.kflh.boxApi.chooseSignalSource.entity.CloseOrder">
        <result column="id" jdbcType="INTEGER" property="id"/>
        <result column="closeorder" jdbcType="INTEGER" property="closeOrder"/>
        <result column="account" jdbcType="INTEGER" property="account"/>
        <result column="symbol" jdbcType="VARCHAR" property="symbol"/>
        <result column="cmd" jdbcType="TINYINT" property="cmd"/>
        <result column="Volume" jdbcType="DOUBLE" property="volume"/>
        <result column="OpenTime" jdbcType="INTEGER" property="openTime"/>
        <result column="OpenPrice" jdbcType="DECIMAL" property="openPrice"/>
        <result column="SL" jdbcType="DECIMAL" property="sl"/>
        <result column="TP" jdbcType="DECIMAL" property="tp"/>
        <result column="Magic" jdbcType="INTEGER" property="magic"/>
        <result column="Comment" jdbcType="VARCHAR" property="comment"/>
        <result column="timestamp" jdbcType="INTEGER" property="timestamp"/>
        <result column="Profit" jdbcType="DECIMAL" property="profit"/>
        <result column="ClosePrice" jdbcType="DECIMAL" property="closePrice"/>
        <result column="Digits" jdbcType="TINYINT" property="digits"/>
        <result column="Storage" jdbcType="VARCHAR" property="storage"/>
    </collection>
</resultMap>

<!--按照指定字段分組並將分組得數據進行返回-->
<select id="selectCloseOrderList"  resultMap="customResultMap">
    select
     <include refid="Base_Column_List"/>
     from closeorder where account in(select account from mt4list_rel)
</select>

五.傳參得時候能夠使用map進行傳參

controller

@Autowired
EaQuanXianService eaQuanXianService;

@RequestMapping(value = "insertWestfieldAccountIndex",method = RequestMethod.GET)
@ResponseBody
public JsonResult insertWestfieldAccountIndex(String param) {
    String[] arr = param.split("@");
    //帳號@本地時間@服務器時間@淨值@餘額
    if (arr.length != 12) {
        throw new ServiceException(ResultEnum.LOSTPARAMS);
    }
    //初始淨值
    String equity=eaQuanXianService.selectEquity(Integer.parseInt(arr[0]));
    Double cha=DoubleCalendar.subtract(arr[2],equity);
    Double profitability= DoubleCalendar.divideFloat(cha.toString(),equity);

    Map<String,Object> map=new HashedMap();
    map.put("account",arr[0]);
    map.put("localtime",DateUtil.strToDate(arr[1]));
    map.put("equity",arr[2]);
    map.put("balance",arr[3]);
    map.put("floating",arr[4]);
    map.put("grossProfit",arr[5]);
    map.put("grossLoss",arr[6]);
    map.put("closeVolume",arr[7]);
    map.put("closeOrderNum",arr[8]);
    map.put("tradeVolume",arr[9]);
    map.put("tradeOrderNum",arr[10]);
    map.put("nightInterest",arr[11]);
    map.put("profitability",profitability);
    eaQuanXianService.insertWestfieldAccountIndex(map);
    return new JsonResult();
}

serviceImpl中的方法

@Autowired
EaQuanXianMapper eaQuanXianMapper;

@Override
public int insertWestfieldAccountIndex(Map<String, Object> map) {
    int num = eaQuanXianMapper.insertWestfieldAccountIndex(map);
    if (num <= 0) {
        throw new ServiceException(ResultEnum.INSERTWESTFIELDACCOUNTINDEXFAILED);
    }
    return num;
}

dao文件

int insertWestfieldAccountIndex(Map<String ,Object> map);

xml文件

<insert id="insertWestfieldAccountIndex">
    insert into westfield_account_index values
    (null,#{account},#{localtime},#{equity},#{balance},#{floating},#{grossProfit},
    #{grossLoss},#{closeVolume},#{closeOrderNum},#{tradeVolume},#{tradeOrderNum},
    #{profitability},#{nightInterest})
</insert>

總結:
當從java傳map進入mybatis的時候,mybatis須要將map中的具體值取出來,此時就是把map中的key取出來,放入進去便可.也就是說在將參數放入map時得key與mybatis中的取值名稱一致
map.put("equity",arr[2])-->mybatis取出來得時候#{equity}

六.常規創建實體類,傳實體類或者傳具體參數

常規用法

七.傳的參數時List可是其中包含的時Map得時候

//dao文件
void insertAccountFilterResultBatch(@Param(value = "list") List<Map<String,Object>> list);

//xml文件
<insert id="insertAccountFilterResultBatch" parameterType="java.util.List">
    insert into account_filter_results values
        <foreach collection="list" index="index" item="item" separator=",">
            (null,#{item.account},#{item.equity},#{item.inMoney},#{item.outMoney},#{item.createTime},
            #{item.totalProfit},#{item.profitRate},#{item.allOrderNum},#{item.allVolumes},
            #{item.historyProfit},#{item.avgVolume},#{item.maxRetracement},'1',now())
        </foreach>
</insert>

總結: 在mybatis的xml文件進行取值得時候,使用foreach標籤,籤內元素不要使用open及close屬性,不然會將全部循環的元素包括進open及close中的大標籤中.其中循環體item爲Map對象,此時取出其中具體的值得時候須要使用#{item.account},其中account爲map中的key