mapper.xml使用循环语句

List<实体类> getList(Map<String,Object> paraMap);

<!--select:对应sql的select语句, id：方法名，parameterType：参数类型,resultMap：返回对象类型(BaseResultMap：标签-->
<!--<resultMap id="BaseResultMap" type="实体类包路径"> 实体类的映射 不改的话一般都是这个名字)-->
<select id="getList" parameterType="java.util.Map" resultMap="BaseResultMap">
  select * from table where 
  <!-- 判断-->
  <if test="a!= null">
      a = #{a,jdbcType=VARCHAR}
  </if>
  <if test="list!= null">
    and id in
    <!-- for循环, item:循环后的值, index:循环下标列式for循环的 i ,collection:参数名-->
    <!-- open="(" close=")" separator="," 就是把循环的值组成 (item1,item2,item3)的格式-->
    <foreach item="item" index="index" collection="list" open="(" close=")" separator=",">
     #{item}
    </foreach>
  </if>
</select>

Map<String,Object> map = new HashMap<String, Object>();
map.put("a","参数");
map.put("list",数组、List都行)
List<实体类> list = mapper.getList(map);

package com.youkeda.comment.dao;
import com.youkeda.comment.dataobject.UserDO;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import java.time.LocalDateTime;
import java.util.List;
@Mapper
public interface UserDAO {
    int batchAdd(@Param("list") List<UserDO> userDOs);
}

<insert id="batchAdd" parameterType="java.util.List" useGeneratedKeys="true" keyProperty="id">
    INSERT INTO user (user_name, pwd, nick_name,avatar,gmt_created,gmt_modified)
    VALUES
    <foreach collection="list" item="it" index="index" separator =",">
        (#{it.userName}, #{it.pwd}, #{it.nickName}, #{it.avatar},now(),now())
    </foreach >
</insert>

package com.youkeda.comment.dao;
import com.youkeda.comment.dataobject.UserDO;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import java.time.LocalDateTime;
import java.util.List;
@Mapper
public interface UserDAO {
    List<UserDO> findByIds(@Param("ids") List<Long> ids);
}

<select id="findByIds" resultMap="userResultMap">
    select * from user
    <where>
        id in
        <foreach item="item" index="index" collection="ids"
                    open="(" separator="," close=")">
            #{item}
        </foreach>
    </where>
</select>

select * from user where id in (?,?,?)