1.mybatis传入map参数，map中包含list:
List<FukaModel> fukaModels = price.getSchemaPrice().getFukaList();
Map<String, Object> objectMap = new HashMap<>();
objectMap.put("schemaId", schemaId);
objectMap.put("list", fukaModels);
sqlSession.insert("insertFukaData",objectMap);
<select id="insertFukaData" parameterType="map" >
<foreach collection="list" item="item" index="index" open="" separator=";" close="">
INSERT INTO jj_fokas_deduct (price_schema_id,min_num, max_num, user_grade)
VALUES (#{schemaId},0,#{item.num},#{item.userGrade})
</foreach>
</select>
2.
List<JjActivityRecommendSku> activityRecommendSkuList = new ArrayList<>();
sqlSession.insert("insertActivityRecommendSkuList", activityRecommendSkuList);
<insert id="insertActivityRecommendSkuList" parameterType="ActivityRecommendSku" >
insert into activity_recommend_sku (rec_sku_id, activity_id, sku_id,
sku_sort_order)
values
<foreach collection="list" item="item" index="index" separator=",">
(#{item.recSkuId,jdbcType=INTEGER}, #{item.activityId,jdbcType=INTEGER}, #{item.skuId,jdbcType=VARCHAR},
#{item.skuSortOrder,jdbcType=INTEGER})
</foreach>
</insert>
3.
<update id="unShelveGoodsSku" parameterType="java.util.List">
update goods_sku set status = 5 where status = 4 and sku_id in
<foreach item="item" index="index" collection="list"
open="(" separator="," close=")">
#{item}
</foreach>
</update>
4.
List<String> skuIds = s.selectList(statement,param);
Map<String, Object> map = new HashMap<>();
map.put("storeId",storeId);
map.put("devType",devType);
map.put("list",skuIds);
WHERE SkuId In
<foreach item="sku_id" collection="list" index="index" open="(" separator="," close=")">
#{sku_id}
</foreach>
5.lambda表达式
currencyDataListTemp.stream().collect(Collectors.groupingBy(o-> new CurrencyData(o.getCurrencyDtID(),o.getCurrencyAtID(),o.getCurrencyOriID(),o.getCurrencyName()),Collectors.summingInt(o->o.getReturnAmount()))).forEach((k,v)->{
k.setReturnAmount(v);
currencyDataList.add(k);
});
重写CurrencyData的hash和equals方法：
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
CurrencyData currencyData = (CurrencyData) o;
return Objects.equals(currencyDtID, currencyData.currencyDtID) &&
Objects.equals(currencyAtID, currencyData.currencyAtID) &&
Objects.equals(currencyOriID, currencyData.currencyOriID) &&
Objects.equals(currencyName, currencyData.currencyName) &&
Objects.equals(returnAmount, currencyData.returnAmount);
}
@Override
public int hashCode() {
return Objects.hash(currencyDtID, currencyAtID, currencyOriID,currencyName);
}
6.
public static <T>List<T> checkListRepeat(List<T> list) {
return list.stream()
.collect(Collectors.toMap(k -> k, v -> 1, (a, b) -> a + b))
.entrySet().stream()
.filter(entry -> entry.getValue() > 1)
.map(Map.Entry::getKey)
.collect(Collectors.toList());
}
7.
List<Test> list = new ArrayList<>();
// list.add(new Test("一年级二班", "小明"));
list.add(new Test("一年级二班啊", "小芳"));
list.add(new Test("一年级二班", "小华"));
list.add(new Test("一年级三班啊", "翠花"));
list.add(new Test("一年级三班", "香兰"));
// 集合中对象属性转map
Map<String, String> map = list.stream().collect(Collectors.toMap(Test :: getClassName, Test :: getStudentName));
8.
double sumRate = lotteryProbList.stream().mapToDouble(Double::doubleValue).sum();
9.
Map<String, List<CommodityInfo>> listMap = commodityInfoList.stream().collect(Collectors.groupingBy(model -> model.getCommodityId()));
