当只向xxxMapper.xml文件中传递一个参数时,可以简单的用“_parameter”来接收xxxMapper.java传递进来的参数,并代入查询,比如说这样:


(1)xxxMapper.java文件中这样定义:



List<String> selectAllAirportCode(Boolean mapping);

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List<String> selectAllAirportCode(Boolean mapping);

(2)这时在对应的xxxMapper.xml文件中可以使用“_parameter”来接收这个参数:



<select id="selectAllAirportCode" resultType="java.lang.String"

parameterType="java.lang.Boolean">

select DEPARTURE_AIRPORT from USR_AIR_LINE union select

ARRIVAL_AIRPORT from USR_AIR_LINE

<if test="_parameter == true">

union select REL_DEPARTURE_AIRPORT from USR_AIR_LINE union

select

REL_ARRIVAL_AIRPORT from USR_AIR_LINE

</if>

</select>

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<select id="selectAllAirportCode" resultType="java.lang.String"

    parameterType="java.lang.Boolean">

    select DEPARTURE_AIRPORT from USR_AIR_LINE union select

    ARRIVAL_AIRPORT from USR_AIR_LINE

    <if test="_parameter == true">

        union select REL_DEPARTURE_AIRPORT from USR_AIR_LINE union

        select

        REL_ARRIVAL_AIRPORT from USR_AIR_LINE

    </if>

</select>

但是,如果在xxxMapper.java文件中传递进来多个参数,就不能使用上面这种形式来接收参数,这时可以有两种方案来解决这个问题:


一 向xml文件中传递进去一个Map<String, Object>集合,然后xml文件中就可以正常使用Map集合中的各个参数了。具体实例如下:


(1)xxxMapper.java文件中这样定义:




List<Airline> findAll(Map<String, Object> parms);

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List<Airline> findAll(Map<String, Object> parms);

(2)在用到上面定义的具体实现类中给Map传参:




public List<Airline> findAll(PageInfo page,Airline airline) {

HashMap<String,Object> params = new HashMap<String,Object>();

params.put("page", page);

params.put("airline", airline);

return airlineMapper.findAll(params);

}

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public List<Airline> findAll(PageInfo page,Airline airline) {

        HashMap<String,Object> params = new HashMap<String,Object>();

        params.put("page", page);

        params.put("airline", airline);

        

        return airlineMapper.findAll(params);

    }

(3)此时对应的xxxMapper.xml文件使用“java.util.Map”来接收这个Map集合:




<sql id="sqlfileders">

<bind name="fileders"

value="#{'id':'ID','departureAirport':'DEPARTURE_AIRPORT','relDepartureAirport':'REL_DEPARTURE_AIRPORT','arrivalAirport':'ARRIVAL_AIRPORT','relArrivalAirport':'REL_ARRIVAL_AIRPORT','popStatus':'POP_STATUS','status':'STATUS','creator':'CREATOR','createTime':'CREATE_TIME'}" />

<bind name="javapropertys"

value="#{'ID':'id','DEPARTURE_AIRPORT':'departureAirport','REL_DEPARTURE_AIRPORT':'relDepartureAirport','ARRIVAL_AIRPORT':'arrivalAirport','REL_ARRIVAL_AIRPORT':'relArrivalAirport','POP_STATUS':'popStatus','STATUS':'status','CREATOR':'creator','CREATE_TIME':'createTime'}" />

</sql>

<select id="findAll" resultMap="BaseResultMap" parameterType="java.util.Map">

    <![CDATA[

      select x.* from (

      select z.*, rownum numbers from (

    ]]>

select

<include refid="Base_Column_List" />

from

USR_AIR_LINE

<where>

<if test="airline.departureAirport != null">

DEPARTURE_AIRPORT = #{airline.departureAirport}

</if>

<if test="airline.arrivalAirport != null">

and ARRIVAL_AIRPORT=#{airline.arrivalAirport}

</if>

<if test="airline.relDepartureAirport != null">

and REL_DEPARTURE_AIRPORT =

#{airline.relDepartureAirport}

</if>

<if test="airline.relArrivalAirport != null">

and REL_ARRIVAL_AIRPORT = #{airline.relArrivalAirport}

</if>

<if test="airline.popStatus != null">

and POP_STATUS = #{airline.popStatus}

</if>

<if test="airline.status != null">

and STATUS = #{airline.status}

</if>

</where>

<if test="page.sortName != null">

<include refid="sqlfileders" />

<bind name="orderfield" value="#this.fileders[page.sortName]" />

order by ${orderfield} ${page.sortOrder}

</if>

    <![CDATA[ ) z where rownum < ]]>

#{page.to}

    <![CDATA[ ) x where x.numbers >= ]]>

#{page.from}

</select>

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<sql id="sqlfileders">

        <bind name="fileders"

            value="#{'id':'ID','departureAirport':'DEPARTURE_AIRPORT','relDepartureAirport':'REL_DEPARTURE_AIRPORT','arrivalAirport':'ARRIVAL_AIRPORT','relArrivalAirport':'REL_ARRIVAL_AIRPORT','popStatus':'POP_STATUS','status':'STATUS','creator':'CREATOR','createTime':'CREATE_TIME'}" />

        <bind name="javapropertys"

            value="#{'ID':'id','DEPARTURE_AIRPORT':'departureAirport','REL_DEPARTURE_AIRPORT':'relDepartureAirport','ARRIVAL_AIRPORT':'arrivalAirport','REL_ARRIVAL_AIRPORT':'relArrivalAirport','POP_STATUS':'popStatus','STATUS':'status','CREATOR':'creator','CREATE_TIME':'createTime'}" />

    </sql>

    <select id="findAll" resultMap="BaseResultMap" parameterType="java.util.Map">

    <![CDATA[

         select x.* from (

             select z.*, rownum numbers from (

    ]]>

        select

        <include refid="Base_Column_List" />

        from

        USR_AIR_LINE

        <where>

            <if test="airline.departureAirport != null">

                DEPARTURE_AIRPORT = #{airline.departureAirport}

            </if>

            <if test="airline.arrivalAirport != null">

                and ARRIVAL_AIRPORT=#{airline.arrivalAirport}

            </if>

            <if test="airline.relDepartureAirport != null">

                and REL_DEPARTURE_AIRPORT =

                #{airline.relDepartureAirport}

            </if>

            <if test="airline.relArrivalAirport != null">

                and REL_ARRIVAL_AIRPORT = #{airline.relArrivalAirport}

            </if>

            <if test="airline.popStatus != null">

                and POP_STATUS = #{airline.popStatus}

            </if>

            <if test="airline.status != null">

                and STATUS = #{airline.status}

            </if>

        </where>

        <if test="page.sortName != null">

            <include refid="sqlfileders" />

            <bind name="orderfield" value="#this.fileders[page.sortName]" />

            order by ${orderfield} ${page.sortOrder}

        </if>

    <![CDATA[ ) z where rownum < ]]>

        #{page.to}

    <![CDATA[ ) x where x.numbers >= ]]>

        #{page.from}

    </select>

注:上面的实例实现的是分页查询数据。我们可以发现使用Map来传递参数这种形式并不好,因为这样使得在接口中只有一个Map参数,其他人进行维护的时候并不清楚到底需要向这个Map里面传递什么参数进去




二 通过给参数添加@Param注解来解决问题:


(1)给xxxMapper.java文件的方法中的参数添加@Param注解,这个注解中的值对应xml文件中使用到的参数名称:




Airline selectEffectiveAirline(

@Param("departureAirport") String departureAirport,

@Param("arrivalAirport") String arrivalAirport,

@Param("status") BigDecimal status);

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Airline selectEffectiveAirline(

            @Param("departureAirport") String departureAirport,

            @Param("arrivalAirport") String arrivalAirport,

            @Param("status") BigDecimal status);

(2)此时xxxMapper.xml文件中对应的地方就可以正常使用在@Param注解中对应的值了:




<select id="selectEffectiveAirline" resultMap="BaseResultMap">

select

<include refid="Base_Column_List" />

from

USR_AIR_LINE

<where>

<if test="departureAirport != null">

DEPARTURE_AIRPORT = #{departureAirport}

</if>

<if test="arrivalAirport != null">

and ARRIVAL_AIRPORT=#{arrivalAirport}

</if>

<if test="status != null">

and STATUS = #{status}

</if>

</where>

</select>

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<select id="selectEffectiveAirline" resultMap="BaseResultMap">

        select

        <include refid="Base_Column_List" />

        from

        USR_AIR_LINE

        <where>

            <if test="departureAirport != null">

                DEPARTURE_AIRPORT = #{departureAirport}

            </if>

            <if test="arrivalAirport != null">

                and ARRIVAL_AIRPORT=#{arrivalAirport}

            </if>

            <if test="status != null">

                and STATUS = #{status}

            </if>

        </where>

    </select>

注:需要注意的是if条件判断中的参数和在SQL语句中写法是不一样的,if判断中的变量是没有添加#{ }的






Mybatis

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