小编这次要给大家分享的是Java8如何进行多个字段分组统计，文章内容丰富，感兴趣的小伙伴可以来了解一下，希望大家阅读完这篇文章之后能够有所收获。
创新互联公司长期为上1000+客户提供的网站建设服务，团队从业经验10年，关注不同地域、不同群体，并针对不同对象提供差异化的产品和服务；打造开放共赢平台，与合作伙伴共同营造健康的互联网生态环境。为剑川企业提供专业的成都网站设计、网站制作，剑川网站改版等技术服务。拥有10多年丰富建站经验和众多成功案例,为您定制开发。
Java8进行多个字段分组统计实现代码如下：
// 分组统计
Map countMap = records.stream().collect(Collectors.groupingBy(o -> o.getProductType() + "_" + o.getCountry(), Collectors.counting()));
List countRecords = countMap.keySet().stream().map(key -> {
String[] temp = key.split("_");
String productType = temp[0];
String country = temp[1];
Record record = new Record();
record.set("device_type", productType);
record.set("location", country;
record.set("count", countMap.get(key).intValue());
return record;
}).collect(Collectors.toList());
实例补充：
1.本实例其实可以用一句简单的sql去实现 由于我们项目数据库中时间存的是13位的时间戳 所以必须得转行成日期格式 才能进行分组 如下：
SELECT
count(1) simpleNumber,
SUM(penalty_amount) AS simplePenaltyAmount,
Handling_department,
create_time,
LEFT(FROM_UNIXTIME(LEFT(create_time,10)),7)
FROM
t_case_simple_case
WHERE
1 = 1
GROUP BY Handling_department,LEFT(FROM_UNIXTIME(LEFT(create_time,10)),7)
以上的就能实现多字段求和统计等功能 但我们老大考虑到查询速度和换库等问题 建议我不要用FROM_UNIXTIME（）函数，所以只能用最笨的方法一步步实现 以下是用Java8方式实现的 代码如下：
@Override
public List queryFirstCase(String startTime,String condition,String caseType) {
List statisticalAnalyses = null;
//简易案件
if (caseType.equals(CaseTypeEnum.SIMPLETYPE.code())) {
statisticalAnalyses = statisticalAnalysisDao.querySimpleData();
}
//一般案件
if (caseType.equals(CaseTypeEnum.NORMALTYPE.code())) {
statisticalAnalyses = statisticalAnalysisDao.queryNormalData();
}
for (StatisticalAnalysis analysis : statisticalAnalyses) {
try {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");
String newCreateTime = sdf.format(new Date(Long.valueOf(analysis.getCreateTime())));
analysis.setCreateTime(newCreateTime);
SysOrg sysOrg = commonSearchDao.findByOrgId(analysis.getHandlingDepartment());
if (sysOrg != null) {
analysis.setHandlingDepartmentName(sysOrg.getOrgName());
}
if(analysis.getSimplePenaltyAmount()==null){
analysis.setSimplePenaltyAmount(0.0);
}
} catch (Exception e) {
e.printStackTrace();
}
}
List caseTotalList = new ArrayList<>();
//根据部门 日期进行分组 统计
Map> caseTotal = statisticalAnalyses.stream().collect(Collectors.groupingBy(StatisticalAnalysis::getCreateTime, Collectors.groupingBy(StatisticalAnalysis::getHandlingDepartmentName, Collectors.counting())));
//根据部门 日期进行分组 求和
Map> sumCase = statisticalAnalyses.stream().collect(Collectors.groupingBy(StatisticalAnalysis::getCreateTime, Collectors.groupingBy(StatisticalAnalysis::getHandlingDepartmentName, Collectors.summingDouble(StatisticalAnalysis::getSimplePenaltyAmount))));
//根据年份进行模糊匹配 取出对应的统计值
for (Map.Entry> entry : caseTotal.entrySet()) {
if (entry.getKey().indexOf(startTime) > -1) {
StatisticalAnalysis statisticalAnalysis = new StatisticalAnalysis();
statisticalAnalysis.setCreateTime(entry.getKey());
//将年份-去掉 组成新的数字 主要作为排序
String key = entry.getKey().replace("-", "");
Integer sortNum = Integer.parseInt(key);
statisticalAnalysis.setSortNum(sortNum);
Map map = entry.getValue();
for (Map.Entry entr : map.entrySet()) {
statisticalAnalysis.setHandlingDepartmentName(entr.getKey());
statisticalAnalysis.setSimpleNumber(entr.getValue());
}
caseTotalList.add(statisticalAnalysis);
}
}
caseTotalList.sort((a, b) -> a.getSortNum() - b.getSortNum());
//根据年份进行模糊匹配 取出对应的求和值
List analyses = new ArrayList<>();
for (Map.Entry> entry : sumCase.entrySet()) {
if (entry.getKey().indexOf(startTime) > -1) {
StatisticalAnalysis statisticalAnalysis = new StatisticalAnalysis();
statisticalAnalysis.setCreateTime(entry.getKey());
//将年份-去掉 组成新的数字 主要作为排序
String key = entry.getKey().replace("-", "");
Integer sortNum = Integer.parseInt(key);
statisticalAnalysis.setSortNum(sortNum);
Map map = entry.getValue();
for (Map.Entry entr : map.entrySet()) {
statisticalAnalysis.setHandlingDepartmentName(entr.getKey());
statisticalAnalysis.setSimplePenaltyAmount(entr.getValue());
}
analyses.add(statisticalAnalysis);
}
}
analyses.sort((a, b) -> a.getSortNum() - b.getSortNum());
//将统计和求和组合成一个新的集合返回前端
List analysisList = new ArrayList<>();
for (StatisticalAnalysis analys : caseTotalList) {
for (StatisticalAnalysis analys2 : analyses) {
StatisticalAnalysis statisticalAnalysis = new StatisticalAnalysis();
if (analys.getSortNum().intValue() == analys2.getSortNum().intValue()) {
statisticalAnalysis.setSimpleNumber(analys.getSimpleNumber());
statisticalAnalysis.setSimplePenaltyAmount(analys2.getSimplePenaltyAmount());
statisticalAnalysis.setCreateTime(analys.getCreateTime());
statisticalAnalysis.setHandlingDepartmentName(analys.getHandlingDepartmentName());
analysisList.add(statisticalAnalysis);
}
}
}
List newAnalysisList = new ArrayList<>();
if (analysisList.size() > 0) {
//查询第一季度
if (condition.equals(YearEnum.FIRST.code())) {
for (StatisticalAnalysis analysis : analysisList) {
StatisticalAnalysis analysis1 = new StatisticalAnalysis();
if (analysis.getCreateTime().indexOf(startTime + "-01") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.FIRST.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.FIRST.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-02") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.FIRST.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.FIRST.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-03") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.FIRST.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.FIRST.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
}
return newAnalysisList;
}
//查询第二季度
if (condition.equals(YearEnum.SECOND.code())) {
for (StatisticalAnalysis analysis : analysisList) {
StatisticalAnalysis analysis1 = new StatisticalAnalysis();
if (analysis.getCreateTime().indexOf(startTime + "-04") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.SECOND.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.SECOND.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-05") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.SECOND.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.SECOND.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-06") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.SECOND.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.SECOND.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
}
return newAnalysisList;
}
//查询第三季度
if (condition.equals(YearEnum.THREE.code())) {
for (StatisticalAnalysis analysis : analysisList) {
StatisticalAnalysis analysis1 = new StatisticalAnalysis();
if (analysis.getCreateTime().indexOf(startTime + "-07") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.THREE.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.THREE.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-08") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.THREE.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.THREE.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-09") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.THREE.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.THREE.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
}
return newAnalysisList;
}
//查询第四季度
if (condition.equals(YearEnum.FOUR.code())) {
for (StatisticalAnalysis analysis : analysisList) {
StatisticalAnalysis analysis1 = new StatisticalAnalysis();
if (analysis.getCreateTime().indexOf(startTime + "-10") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.FOUR.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.FOUR.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-11") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.FOUR.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.FOUR.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-12") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.FOUR.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.FOUR.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
}
return newAnalysisList;
}
//查询上半年 取前六条数据
if (condition.equals(YearEnum.HALF.code())) {
for (StatisticalAnalysis analysis : analysisList) {
StatisticalAnalysis analysis1 = new StatisticalAnalysis();
if (analysis.getCreateTime().indexOf(startTime + "-01") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-02") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-03") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-04") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-05") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-06") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.HALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
}
return newAnalysisList;
}
//查询下半年 后六条数据
if (condition.equals(YearEnum.LASTHALF.code())) {
for (StatisticalAnalysis analysis : analysisList) {
StatisticalAnalysis analysis1 = new StatisticalAnalysis();
if (analysis.getCreateTime().indexOf(startTime + "-07") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-08") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-09") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-10") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-11") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
if (analysis.getCreateTime().indexOf(startTime + "-12") > -1) {
BeanUtils.copyProperties(analysis, analysis1);
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门简易案件");
}else{
analysis1.setTitle(startTime+YearEnum.LASTHALF.desc()+"各部门一般案件");
}
newAnalysisList.add(analysis1);
}
}
return newAnalysisList;
}
if (condition.equals(YearEnum.FULLYEAR.code())) {
for (StatisticalAnalysis analysis : analysisList) {
if(caseType.equals(CaseTypeEnum.SIMPLETYPE.code())){
analysis.setTitle(startTime+YearEnum.FULLYEAR.desc()+"各部门简易案件");
}else{
analysis.setTitle(startTime+YearEnum.FULLYEAR.desc()+"各部门一般案件");
}
}
return analysisList;
}
}
return null;
}
看完这篇关于Java8如何进行多个字段分组统计的文章，如果觉得文章内容写得不错的话，可以把它分享出去给更多人看到。
网站标题：Java8如何进行多个字段分组统计
转载注明：
http://cdweb.net/article/jggijs.html
