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：
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List<String> selectAllAirportCode(Boolean mapping);
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（2）这时在对应的xxxMapper.xml文件中可以使用“_parameter”来接收这个参数：
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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
>
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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：
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List<Airline> findAll(Map<String, Object> parms);
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（2）在用到上面定义的具体实现类中给Map传参：
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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);
}
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（3）此时对应的xxxMapper.xml文件使用“java.util.Map”来接收这个Map集合：
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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
>
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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：
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Airline selectEffectiveAirline(
@Param
(
"departureAirport"
) String departureAirport,
@Param
(
"arrivalAirport"
) String arrivalAirport,
@Param
(
"status"
) BigDecimal status);
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（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：
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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
>
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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
本文转自 pangfc 51CTO博客，原文链接：http://blog.51cto.com/983836259/1772616，如需转载请自行联系原作者
