我使用的时候collection值为mapper的参数名
如：int deleteRoleByUserIds(@Param("userIds") String[] userIds);

<delete id="deleteRoleByUserIds">
    delete from uc_user_role where user_id in 
    <foreach item="item" index="index" collection="userIds" 
           open="(" separator="," close=")">
           #{item}
    </foreach>
</delete>

====================================================
1. 当查询的参数只有一个时

findByIds(List<Long> ids)

1.a 如果参数的类型是List, 则在使用时，collection属性要必须指定为 list

<select id="findByIdsMap" resultMap="BaseResultMap">
         Select
         <include refid="Base_Column_List" />
         from jria where ID in
                  <foreach item="item" index="index" collection="list" 
                         open="(" separator="," close=")">
                        #{item}
                </foreach>
  </select>

findByIds(Long[] ids)

1.b 如果参数的类型是Array,则在使用时，collection属性要必须指定为 array

<select id="findByIdsMap" resultMap="BaseResultMap">
                 select
                 <include refid="Base_Column_List" />
          from jria where ID in
                  <foreach item="item" index="index" collection="array" 
                         open="(" separator="," close=")">
                        #{item}
                </foreach>
  </select>

2. 当查询的参数有多个时,例如 findByIds(String name, Long[] ids)

这种情况需要特别注意，在传参数时，一定要改用Map方式, 这样在collection属性可以指定名称

下面是一个示例

Map<String, Object> params = new HashMap<String, Object>(2);
        params.put("name", name);
         params.put("ids", ids);
        mapper.findByIdsMap(params);
 
 <select id="findByIdsMap" resultMap="BaseResultMap">
                 select
                 <include refid="Base_Column_List" />
          from jria where ID in
                  <foreach item="item" index="index" collection="ids" 
                         open="(" separator="," close=")">
                        #{item}
                </foreach>
   </select>

完整的示例如下:

例如有一个查询功能，Mapper接口文件定义如下方法:

List<Jria> findByIds(Long... ids);

使用 in 查询的sql拼装方法如下:

<select id="findbyIds" resultMap="BaseResultMap">
                 select
                 <include refid="Base_Column_List" />
          from jria where ID in
                  <foreach item="item" index="index" collection="array" 
                         open="(" separator="," close=")">
                        #{item}
                </foreach>
  </select>