我们在执行java多线程并发程序时有时候会碰到执行特别慢的场景，小伙伴们知道是什么原因导致的吗?它要怎么解决呢?下面小编就为你讲讲。
前提：在某地需要开发一个应用系统，此系统主要功能是能够让一些中小型企业填写企业资质信息，然后通过给定的公式，统计这一系列的信息，再以得分的形式展示给上头。当前总共有着1300家企业填报。因为得分是需要实时显示的，因此统计功能会慢到一定程度。
具体代码流程：
a.首先查出1300企业信息
b.循环遍历1300家企业的所有信息，并计算每家企业的具体得分。每家预计时间为0.3秒。合计390秒。所以页面请求超时
c.导出(jxl或jar)
给出解决方案：
因为是处理业务的，所以我们需要能有返回值的线程。因此会使用：Callable
实现
1、调用线程代码
List < Map < String, Object >> list = (List < Map < String, Object >> ) map.get("rows");
int taskSize = 20;
// 创建一个线程池
ExecutorService pool = Executors.newFixedThreadPool(taskSize);
// 创建多个有返回值的任务
List < Future > listFuture = new ArrayList < Future > ();
for (int i = 0; i < taskSize; i++)
{
System.out.println("我启用多线程啦啦啦");
int evgCount = list.size() / taskSize;
Callable c = new MyCallable(list.subList(evgCount * i, evgCount * (i + 1)), session, staticFlag
, declareService, declareMasterService, enterpriseQueryService);
// 执行任务并获取Future对象
Future f = pool.submit(c);
listFuture.add(f);
}
pool.shutdown();
// 获取所有并发任务的运行结果
List < Map < String, Object >> listResult = new ArrayList < Map < String, Object >> ();
for (Future f: listFuture)
{
List < Map < String, Object >> listModel = new ArrayList < Map < String, Object >> ();
try
{
listModel = (List < Map < String, Object >> ) f.get();
}
catch (InterruptedException e)
{
e.printStackTrace();
}
catch (ExecutionException e)
{
e.printStackTrace();
}
listResult.addAll(listModel);
}
map.put("rows", listResult);2、线程代码
package usi.jszx.controller;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Callable;
import javax.servlet.http.HttpSession;
import org.apache.commons.lang3.StringUtils;
import usi.jszx.entity.ScoreMain;
import usi.jszx.service.DeclareMasterService;
import usi.jszx.service.DeclareService;
import usi.jszx.service.EnterpriseQueryService;
import usi.sys.dto.AuthInfo;
import usi.sys.util.ConstantUtil;
class MyCallable implements Callable < Object >
{
//-----------------以下为线程调用的方法----------------
private List < Map < String
, Object >> list;
private HttpSession session;
private String staticFlag;
private DeclareService declareService;
private DeclareMasterService declareMasterService;
private EnterpriseQueryService enterpriseQueryService;
public MyCallable(List < Map < String, Object >> list, HttpSession session, String staticFlag
, DeclareService declareService, DeclareMasterService declareMasterService, EnterpriseQueryService enterpriseQueryService)
{
this.list = list;
this.session = session;
this.staticFlag = staticFlag;
this.declareService = declareService;
this.declareMasterService = declareMasterService;
this.enterpriseQueryService = enterpriseQueryService;
}
@Override
public Object call() throws Exception
{
AuthInfo info = (AuthInfo) session.getAttribute(ConstantUtil.AUTH_INFO);
for (int i = 0; i < list.size(); i++)
{
Map < String, Object > maplist = list.get(i);
String mainId = maplist.get("ID") + "";
this.gradeMaster(session, mainId, maplist.get("orgId") + "", declareMasterService, enterpriseQueryService);
List < Map < String, Object >> listscore = declareMasterService.queryScoreMain(maplist.get("ID") + "", info.getRightType(), "report");
// declareMasterService.queryScoreMain(mainId,info.getRightType(),isreport);
int isdouble = 1;
if (listscore.size() > 30)
{
maplist.put("SOCRETOTAL", listscore.get(46)
.get("SCORE"));
isdouble = 2;
}
else if (listscore.size() > 22)
{
maplist.put("SOCRETOTAL", listscore.get(23)
.get("SCORE"));
}
if ("3".equals(staticFlag))
{
for (int j = 0; j < 23; j++)
{
if (j < 9)
{
maplist.put("VALUE0" + (j + 1), listscore.get(j * isdouble)
.get("SHOW_VALUE"));
}
else
{
maplist.put("VALUE" + (j + 1), listscore.get(j * isdouble)
.get("SHOW_VALUE"));
}
}
}
//地市展示
String COUNTYID = maplist.get("COUNTYID") + "";
if ("340826".equals(COUNTYID) || "341822".equals(COUNTYID))
{
maplist.put("CITYNAME", maplist.get("COUNTYNAME") + "");
}
//企业类型
String DECLARE_EVALUATE = maplist.get("DECLARE_EVALUATE") + "";
if ("1".equals(DECLARE_EVALUATE))
{
maplist.put("DECLARE_EVALUATE_NAME", "申报");
}
else
{
maplist.put("DECLARE_EVALUATE_NAME", "评价");
}
//审核状态
String SHSTATUS = maplist.get("SHSTATUS") + "";
if ("9".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "草稿");
}
else if ("0".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "企业提交");
}
else if ("1".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "市审核通过");
}
else if ("2".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "市审核不通过");
}
else if ("3".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "省审核通过");
}
else if ("4".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "省审核不通过");
}
else if ("5".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "省级审核中");
}
else if ("6".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "退回企业修改");
}
else if ("7".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "市级审核中");
}
else if ("11".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "修改为申报");
}
else if ("12".equals(SHSTATUS))
{
maplist.put("STRSHSTATUS", "修改为评价");
}
if ("1".equals(staticFlag))
{
//添加修改意见
List < Map < String, Object >> listDetail = declareService.queryAuditLog(mainId);
if (listDetail.size() > 0)
{
String AUDIT_OPINION = listDetail.get(0)
.get("AUDIT_OPINION") + "";
if (!StringUtils.isEmpty(AUDIT_OPINION) && !"null".equals(AUDIT_OPINION))
{
maplist.put("AUDIT_OPINION", AUDIT_OPINION);
}
else
{
maplist.put("AUDIT_OPINION", "");
}
}
//是否更名 曾用名
String ORGNAME = maplist.get("ORGNAME") + "";
String PJNAME = maplist.get("PJNAME") + "";
if (StringUtils.isEmpty(PJNAME) || "null".equals(PJNAME) ||
PJNAME.equals(ORGNAME))
{
maplist.put("ISGENGMING", "否");
maplist.put("PJNAME_E", "");
}
else
{
maplist.put("ISGENGMING", "是");
maplist.put("PJNAME_E", PJNAME);
}
}
else if ("2".equals(staticFlag))
{}
}
return list;
}
public float gradeMaster(HttpSession session, String mainId, String orgId
, DeclareMasterService declareMasterService, EnterpriseQueryService enterpriseQueryService)
{
AuthInfo info = (AuthInfo) session.getAttribute(ConstantUtil.AUTH_INFO);
String rightType = info.getRightType();
declareMasterService.deleteScoreMain(mainId);
float[] resultFirst = new float[100];
/*
* 先查询所有 附表列表
* 查看得分的地方，是直接查找主表数据的
*
* 既然审核了，主表数据肯定存起来了
* */
List < Map < String, Object >> listDetail = declareMasterService.queryTaskDetail(mainId);
if ("2".equals(rightType) || "3".equals(rightType))
{
//将String 转为 float
for (int i = 0; i < listDetail.size(); i++)
{
Map < String, Object > map = listDetail.get(i);
if (StringUtils.isEmpty(map.get("DECLARE_CITY_VALUE") + "") ||
"null".equals(map.get("DECLARE_CITY_VALUE") + ""))
{
resultFirst[i] = 0 f;
}
else
{
resultFirst[i] = float.parsefloat(map.get("DECLARE_CITY_VALUE") + "");
}
}
}
else
{
//将String 转为 float
for (int i = 0; i < listDetail.size(); i++)
{
Map < String, Object > map = listDetail.get(i);
if (StringUtils.isEmpty(map.get("DECLARE_PROVINCE_VALUE") + "") ||
"null".equals(map.get("DECLARE_PROVINCE_VALUE") + ""))
{
resultFirst[i] = 0 f;
}
else
{
resultFirst[i] = float.parsefloat(map.get("DECLARE_PROVINCE_VALUE") + "");
}
}
}
Map < String, Object > enterprise = enterpriseQueryService.getInfoByOrgId(orgId)
.get(0);
//根据 湖南省企业技术中心评价指标计算公式 进行算值 下一步算分
float ratio1 = 0 f;
float ratio2 = 0 f;
float ratio3 = 0 f;
try
{
ratio1 = float.parsefloat(enterprise.get("RATIO1") + "");
ratio2 = float.parsefloat(enterprise.get("RATIO2") + "");
ratio3 = float.parsefloat(enterprise.get("RATIO3") + "");
}
catch (Exception e)
{}
Map < String, Object > map = DeclareController.getValue(resultFirst, ratio1, ratio2, ratio3);
float[] resultValue = (float[]) map.get("resultValue");
float[] resultScoreValue = (float[]) map.get("resultScoreValue");
float[] resultScore = DeclareController.getScore(resultScoreValue);
float scoreTotal = 0 f;
List < Map < String, Object >> listScore = declareMasterService.queryScoreDic();
for (int i = 0; i < listScore.size(); i++)
{
ScoreMain scoreMain = new ScoreMain();
scoreMain.setMainId(mainId);
scoreMain.setScoreName(listScore.get(i)
.get("SCORE_NAME") + "");
scoreMain.setScoreUnit(listScore.get(i)
.get("SCORE_UNIT") + "");
scoreMain.setScoreWeight(listScore.get(i)
.get("SCORE_WEIGHT") + "");
scoreMain.setDisOrder(listScore.get(i)
.get("DIS_ORDER") + "");
scoreMain.setShowValue(resultValue[i] + "");
scoreMain.setScoreValue(resultScoreValue[i] + "");
scoreMain.setScore(resultScore[i] + "");
declareMasterService.inserScoreMain(scoreMain);
scoreTotal += resultScore[i];
}
return scoreTotal;
}
}PS：可以看到最后从390秒提速致40秒，提升巨大
以上就是整篇文章的所有内容，相信对多线程大家都已经非常了解了吧，还想了解更多相关java常见问题及解决方法的话就快关注我们网站吧。
推荐阅读：