去重优先选择group by
也可以用distinct
尽量不要用row_number() 函数（会影响工作效率）
三者区别
www.cnblogs.com/171207xiaoh…
Java代码质量优化提升篇
请看修改前的代码
是不是好长
但不太复杂
@PostMapping("/list")
@ApiOperation(value = "竞对分析列表显示")
public BaseResponse<ReportCompeteListResp> list(@RequestBody ReportCompeteListReq listReq) {
List<CompeteProductResp> competeProductRespList = new ArrayList<CompeteProductResp>();
List<CompeteProductNoDupResp> competeProductRespNoDupList = new ArrayList<CompeteProductNoDupResp>();
JiHaiBrandReq jiHaiBrandReq = new JiHaiBrandReq();
jiHaiBrandReq.setRegionCode(listReq.getRegionCode());
jiHaiBrandReq.setBrandCodeList(listReq.getBrandCodeList());
List<JiHaiBrandResp> jiHaiPoiRespList = dataService.listJiHaiBrandDataByBrandCode(jiHaiBrandReq).getData();
if (CollectionUtil.isNotEmpty(jiHaiPoiRespList)) {
for (JiHaiBrandResp jiHaiBrandResp : jiHaiPoiRespList) {
CompeteProductResp competeProductResp = new CompeteProductResp();
String brandName = jiHaiBrandResp.getBrandName();
if (null != brandName) {
competeProductResp.setBrandName(brandName);
int count = getCount(jiHaiPoiRespList, brandName);
competeProductResp.setCount(Long.valueOf(count));
boolean res = competeProductRespList.contains(competeProductResp);
if (!res) {
competeProductRespList.add(competeProductResp);
}
}
CompeteProductNoDupResp competeProductNoDupResp = new CompeteProductNoDupResp();
competeProductNoDupResp.setBrandName(jiHaiBrandResp.getBrandName());
competeProductNoDupResp.setLatitude(jiHaiBrandResp.getLatitude());
competeProductNoDupResp.setLongitude(jiHaiBrandResp.getLongitude());
if (null != competeProductNoDupResp) {
competeProductRespNoDupList.add(competeProductNoDupResp);
}
}
}
ReportCompeteListResp reportCompeteListResp = new ReportCompeteListResp();
reportCompeteListResp.setCompeteProductRespList(competeProductRespList);
reportCompeteListResp.setCompeteProductNoDupRespList(competeProductRespNoDupList);
try {
List<CompeteMarketResp> competeMarketRespList =
dataService.getByRegionId(Integer.valueOf(listReq.getRegionCode())).getData();
reportCompeteListResp.setCompeteMarketRespList(competeMarketRespList);
} catch (Exception e) {
e.printStackTrace();
}
return BaseResponse.ok(reportCompeteListResp);
}
private int getCount(List<JiHaiBrandResp> jiHaiPoiRespList, String brandName) {
int count = 0;
if (null != brandName) {
for (JiHaiBrandResp haiBrandResp : jiHaiPoiRespList) {
if (brandName.equals(haiBrandResp.getBrandName())) {
count++;
}
}
}
return count;
}
问题：
命名不规范
如CompeteProductNoDupResp 太长了
当数据量过多的时候，List执行效率不高
优化
Map登场
在以远程调用接口listJiHaiBrandDataByBrandCode得到这么一个list
List jiHaiPoiRespList
我们得到的数据就是brandName为key
brandName有统计的，和地图所有详细要展示的longitude、latitude经纬度
解决第一个汇总的，第一种方法是把所有的得到的值都遍历了一遍，很明显数据量大的时候有许多重复的，如1 1 1 2 1 2 3 3 3 3 3 3 3 1 1 1 1 1 数据量多将使得程序非常的慢，浪费时间
根据brandName先分类，在遍历才是王道
把1 1 1 2 1 2 3 3 3 3 3 3 3 1 1 1 1 1
得到key，map在这个时候体现了去重的本质
key只能是唯一的
把list给到value
Map<String, List> jiHaiBrandMap = jiHaiPoiRespList.stream().collect(Collectors.groupingby(JiHaiBrandResp::getBrandName))
Collectors.groupingBy根据一个或多个属性对集合中的项目进行分组
上述代码是根据BrandName来分组的
实现了上述的思路
得到
1 ---------- 原来那个集合by 1
2 ----------- 原来那个集合by 2
3 ------------- 原来那个集合by 3
。。。。。。
而不是把集合所有的东西都拿出来编辑
在外面对key 1 2 3。。。。进行遍历
拿到key
拿到value
遍历
jiHaiBrandMap.forEach((key, value) ->
compterProductResp.setCount((CollectionUtil.isEmpty(value) ? 0 : value.size()));
。。。。。。
)
到这里第一大部统计的完成了
第二三大部还是按以前的来 哈哈哈哈哈 因为第二大部本来就是查详细的避免不了一个个查出的
其实可以优化，但这里作为一个例子不在继续了。
改造后的代码明显质量提高了些
@PostMapping("/data")
@ApiOperation(value = "竞对分析列表显示")
public BaseResponse<ReportCompeteListResp> competeReportData(@RequestBody ReportCompeteListReq listReq) {
ReportCompeteListResp reportCompeteListResp = new ReportCompeteListResp();
List<JiHaiBrandResp> jiHaiPoiRespList = getJiHaiBrandResps(listReq);
if (CollectionUtil.isNotEmpty(jiHaiPoiRespList)) {
reportCompeteListResp.setCompeteProductList(getCompeteProductRespList(jiHaiPoiRespList));
reportCompeteListResp.setCompeteProductDetailList(getCompeteProductDetailResps(jiHaiPoiRespList));
}
try {
List<CompeteMarketResp> competeMarketRespList =
dataService.getByRegionId(Integer.valueOf(listReq.getRegionCode())).getData();
reportCompeteListResp.setCompeteMarketRespList(competeMarketRespList);
} catch (Exception e) {
log.error("获取商场数据发生异常 e:{}", e);
}
return BaseResponse.ok(reportCompeteListResp);
}
private List<CompeteProductNoDupResp> getCompeteProductDetailResps(List<JiHaiBrandResp> jiHaiPoiRespList) {
List<CompeteProductNoDupResp> competeProductRespNoDupList = new ArrayList<CompeteProductNoDupResp>();
for (JiHaiBrandResp jiHaiBrandResp : jiHaiPoiRespList) {
CompeteProductNoDupResp competeProductNoDupResp = new CompeteProductNoDupResp();
competeProductNoDupResp.setBrandName(jiHaiBrandResp.getBrandName());
competeProductNoDupResp.setLatitude(jiHaiBrandResp.getLatitude());
competeProductNoDupResp.setLongitude(jiHaiBrandResp.getLongitude());
competeProductRespNoDupList.add(competeProductNoDupResp);
}
return competeProductRespNoDupList;
}
private List<CompeteProductResp> getCompeteProductRespList(List<JiHaiBrandResp> jiHaiPoiRespList) {
Map<String, List<JiHaiBrandResp>> jiHaiBrandMap = jiHaiPoiRespList.stream()
.collect(Collectors.groupingBy(JiHaiBrandResp::getBrandName));
List<CompeteProductResp> competeProductRespList = new ArrayList<CompeteProductResp>();
jiHaiBrandMap.forEach((key, value) -> {
CompeteProductResp competeProductResp = new CompeteProductResp();
competeProductResp.setBrandName(key);
competeProductResp.setCount((CollectionUtil.isEmpty(value) ? 0 : value.size()));
competeProductRespList.add(competeProductResp);
});
return competeProductRespList;
}
private List<JiHaiBrandResp> getJiHaiBrandResps(ReportCompeteListReq listReq) {
JiHaiBrandReq jiHaiBrandReq = new JiHaiBrandReq();
jiHaiBrandReq.setRegionCode(listReq.getRegionCode());
jiHaiBrandReq.setBrandCodeList(listReq.getBrandCodeList());
List<JiHaiBrandResp> jiHaiPoiRespList = dataService.listJiHaiBrandDataByBrandCode(jiHaiBrandReq).getData();
return jiHaiPoiRespList;
}
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