POCO C++库学习和分析 - 任务

POCOC++库学习和分析--任务任务的定义任务虽然在Poco::Foundation库的目录结构中被单独划出，其实也可以被看成线程的应用，放在线程章节。首先来看一下Poco中对于任务的描述：task主要应用在GUI和Seerver程序中，用于追踪后台线程的进度。应用Poco任务时，需要类Poco::Task和类Poco::TaskManager配合使用。其中类Poco::Task继承自Poco::Runnable，它提供了接口可以便利的报告线程进度。Poco::TaskManager则对Poco::Task进行管理。•为了完成取消和上报线程进度的工作：使用者必须从Poco::Task创建一个子类并重写runTask()函数为了完成进度上报的功能，在子类的runTask()函数中，必须周期的调用setProgress()函数去上报信息为了能够在任务运行时终止任务，必须在子类的runTask()函数中，周期性的调用isCancelled()或者sleep()函数，去检查是否有任务停止请求如果isCancelled()或者sleep()返回真，runTask()返回。•Poco::TaskManager通过使用Poco::NotificationCenter去通知所有需要接受任务消息的对象从上面描述可以看出，Poco中Task的功能就是能够自动汇报线程运行进度。任务用例Task的应用非常简单，下面是其一个使用例子：[cpp]viewplaincopy#include"Poco/Task.h"#include"Poco/TaskManager.h"#include"Poco/TaskNotification.h"#include"Poco/Observer.h"5.usingPoco::Observer;classSampleTask:publicPoco::Task{9.public:6.SampleTask(6.voidrunTask(){for(inti=0;i<100;++i)

{setProgress(float(i)/100);//reportprogressif(sleep(1000))break;}}};classProgressHandlerpublic:voidonProgress(Poco::TaskProgressNotification*pNf){std::cout<<pNf->task()->name()<<"progress:"<<pNf->progress()<<std::endl;pNf->release();}voidonFinished(Poco::TaskFinishedNotification*pNf){std::cout<<pNf->task()->name()<<"finished."<<std::endl;pNf->release();}};intmain(intargc,char**argv){Poco::TaskManagertm;ProgressHandlerpm;tm.addObserver(Observer<ProgressHandler,Poco::TaskProgressNotification>(pm,&ProgressHandler::onProgress));tm.addObserver(Observer<ProgressHandler,Poco::TaskFinishedNotification>(pm,&ProgressHandler::onFinished));tm.start(newSampleTask("Task1"));//tmtakesownershiptm.start(newSampleTask("Task2"));tm.joinAll();return0;}3.Task类图6.57.最后给出Poco中Task的类图。r；m*U|r■“-It| raJo-k+ti!4.liM—訐去:it生霍山■iirEUm■ViiillIniiT肿k>[l 11.r”"柄’I.“Ill时.n|nci中rft-r；m*U|r■“-It| raJo-k+ti!4.liM—訐去:it生霍山■iirEUm■ViiillIniiT肿k>[l 11.r”"柄’I.“Ill时.n|nci中rft-二輛H:vaftttA_h吭咕U±I■tidlflj*c!I-fliphnii*-^■rplcnnuil“"IL'EnirCii-wi■fI3fc'i'•''LllliliJ4-ii-::『4filpriahSH-HMM1:lirvinresH:E血订lLMU-'LllEvC^llEhL'IIIEiLou-F

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