用BCB的INDY组件中的IDHTTP 下载文件并显示出进度条

这篇博客介绍了如何利用BCB中的INDY组件IDHTTP进行文件下载，并在下载过程中实时显示进度条。通过示例代码展示了在按钮点击事件中触发下载，同时在工作开始、进行和结束时更新进度条状态。

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//--------------------------------------------------------------------------- #include <vcl.h> #pragma hdrstop #include "Main.h" //--------------------------------------------------------------------------- #pragma package(smart_init) #pragma link "IdMultipartFormData" #pragma link "IdAntiFreeze" #pragma link "IdAntiFreezeBase" #pragma link "IdBaseComponent" #pragma link "IdComponent" #pragma link "IdHTTP" #pragma link "IdTCPClient" #pragma link "IdTCPConnection" #pragma resource "*.dfm" TForm1 *Form1; //--------------------------------------------------------------------------- __fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) { } //--------------------------------------------------------------------------- void __fastcall TForm1::Button2Click(TObject *Sender) { TMemoryStream *myStream = new TMemoryStream(); try { IdHTTP1->Get("http://mirror4.netgamecar.com/ngc/soft/NetGameCar.exe",myStream); } catch(...) { ShowMessage("网络故障"); myStream->Free(); } myStream->SaveToFile("C://NetGameCar.exe"); myStream->Free(); } //--------------------------------------------------------------------------- void __fastcall TForm1::IdHTTP1WorkBegin(TObject *ASender, TWorkMode AWorkMode, __int64 AWorkCountMax) { Memo_Update->Lines->Add("Begin"); ProgressBar1->Max=AWorkCountMax; ProgressBar1->Min=0; ProgressBar1->Position=0; } //--------------------------------------------------------------------------- void __fastcall TForm1::IdHTTP1Work(TObject *ASender, TWorkMode AWorkMode, __int64 AWorkCount) { ProgressBar1->Position = AWorkCount; } //--------------------------------------------------------------------------- void __fastcall TForm1::IdHTTP1WorkEnd(TObject *ASender, TWorkMode AWorkMode) { Memo_Update->Lines->Add("End"); } //---------------------------------------------------------------------------