gusucode.com > 一个视频压缩并通过网络来传送的源代码 > 一个视频压缩并通过网络来传送的源代码/断点续传和多线程VC源码/code/THttpGetThread.cpp
//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include "THttpGetThread.h"
#pragma package(smart_init)
#pragma link "wininet.lib"
//---------------------------------------------------------------------------
int GetFileSize(const AnsiString &FileName)
{
int FileSize=0;
HANDLE hFile=CreateFile(FileName.c_str(),
GENERIC_READ,
FILE_SHARE_READ,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
if(hFile!=INVALID_HANDLE_VALUE)
{
FileSize=GetFileSize(hFile,NULL);
CloseHandle(hFile);
}
return FileSize;
}
//---------------------------------------------------------------------------
__fastcall THttpGetThread::THttpGetThread(TObject *Owner): TThread(true)
{
FreeOnTerminate = True; // 自动删除
FRepeatCount=5;
FIndex=0;
FOwner=Owner;
FFromBreakpoint=false;
FSuccess=false;
FConnected=false;
iFileHandle=-1;
FFileSize=-2;
dwStart=0;
dwTotal=0;
}
//---------------------------------------------------------------------------
void __fastcall THttpGetThread::Execute()
{
for(int i=0;i<FRepeatCount;i++)
{
StartHttpGet();
GetWebFileSize();
SetFilePointer();
DoHttpGet();
EndHttpGet();
if(FSuccess)break;
}
// 调用完成事件
if(FSuccess)DoOnComplete();
else DoOnError();
}
//---------------------------------------------------------------------------
// 从URL中提取主机名称和下载文件路径
void THttpGetThread::ParseURL(void)
{
AnsiString URL=FURL;
int i=URL.Pos("http://");
if(i>0)
{
URL.Delete(1, 7);
}
i=URL.Pos("/");
FHostName = URL.SubString(1, i-1);
FDownPath = URL.SubString(i, URL.Length());
}
//---------------------------------------------------------------------------
// 打开Internet句柄，初使化下载环境
void THttpGetThread::StartHttpGet(void)
{
if(FConnected)return;
ParseURL();
try
{
// 1.建立会话
FhSession = InternetOpen("http-get-demo",
INTERNET_OPEN_TYPE_PRECONFIG,
NULL,NULL,
0); // 同步方式
if( FhSession==NULL)throw(Exception("Error：InterOpen"));
DoOnStatusText("ok：InterOpen");
// 2.建立连接
FhConnect=InternetConnect(FhSession,
FHostName.c_str(),
INTERNET_DEFAULT_HTTP_PORT,
NULL,NULL,
INTERNET_SERVICE_HTTP, 0, 0);
if(FhConnect==NULL)throw(Exception("Error：InternetConnect"));
DoOnStatusText("ok：InternetConnect");
// 3.初使化下载请求
const char *FAcceptTypes = "*/*";
FhRequest = HttpOpenRequest(FhConnect,
"GET",
FDownPath.c_str(),
"HTTP/1.0",
NULL,
&FAcceptTypes,
INTERNET_FLAG_RELOAD,
0);
if( FhRequest==NULL)throw(Exception("Error：HttpOpenRequest"));
DoOnStatusText("ok：HttpOpenRequest");
// 4.发送下载请求
HttpSendRequest(FhRequest, NULL, 0, NULL, 0);
DoOnStatusText("ok：HttpSendRequest");
FConnected=true;
}catch(Exception &exception)
{
EndHttpGet();
DoOnStatusText(exception.Message);
}
}
//---------------------------------------------------------------------------
int __fastcall THttpGetThread::GetWebFileSize(void)
{
if(FFileSize>-2)return FFileSize;
FFileSize=-1;
if(FConnected==false)StartHttpGet();
if(FConnected==false)return FFileSize;
try
{
// 取得文件的大小
DWORD BufLen=HTTPGET_BUFFER_MAX;
DWORD dwIndex=0;
bool RetQueryInfo=HttpQueryInfo(FhRequest,
HTTP_QUERY_CONTENT_LENGTH,
Buffer, &BufLen,
&dwIndex);
if( RetQueryInfo==false) throw(Exception("Error：HttpQueryInfo"));
DoOnStatusText("ok：HttpQueryInfo");
FFileSize=StrToInt(Buffer); // 文件大小
DoOnGetFileSize(FFileSize);
}catch(Exception &exception)
{
DoOnStatusText(exception.Message);
}
return FFileSize;
}
//---------------------------------------------------------------------------
bool __fastcall THttpGetThread::SetFilePointer(void)
{
int Size=GetWebFileSize();
if(Size<0)return false;
if(dwStart==0)return true;
try
{
// 调整文件指针
bool ReadReturn=InternetSetFilePointer(FhRequest,
dwStart,NULL,FILE_BEGIN,0);
if( ReadReturn==false) throw(Exception("Error：InternetSetFilePointer"));
DoOnStatusText("ok：InternetSetFilePointer");
return true;
}catch(Exception &exception)
{
DoOnStatusText(exception.Message);
}
return false;
}
//---------------------------------------------------------------------------
// 打开输出文件，以保存下载的数据
DWORD THttpGetThread::OpenOutFile(void)
{
try
{
// 打开输出文件，准备保存下载的数据
if(FileExists(FOutFileName))
{
if(FFromBreakpoint) // 使用断点续传
{
DWORD dwCount=GetFileSize(FOutFileName);
if(dwCount>0)
{
iFileHandle=FileOpen(FOutFileName,fmOpenWrite);
FileSeek(iFileHandle,0,2); // 移动文件指针到末尾
if(iFileHandle==-1) throw(Exception("Error：FileCreate"));
DoOnStatusText("ok:OpenFile");
return dwCount;
}
}
DeleteFile(FOutFileName);
}
iFileHandle=FileCreate(FOutFileName);
if(iFileHandle==-1) throw(Exception("Error：FileCreate"));
DoOnStatusText("ok:CreateFile");
}catch(Exception &exception)
{
DoOnStatusText(exception.Message);
}
return 0;
}
//---------------------------------------------------------------------------
// 执行下载过程
void THttpGetThread::DoHttpGet(void)
{
if(FConnected==false)return;
DWORD dwCount=OpenOutFile();
if(dwCount>0) // 调整文件指针
{
dwStart = dwStart + dwCount;
if(!SetFilePointer()) // 服务器不支持操作
{
// 清除输出文件
FileSeek(iFileHandle,0,0); // 移动文件指针到头部
}
}
try
{
// 发出下载事件
DoOnStatusText("StartGet：InternetReadFile");
// 读取数据
DWORD dwRequest; // 请求下载的字节数
DWORD dwRead; // 实际读出的字节数
dwRequest=HTTPGET_BUFFER_MAX;
while(true)
{
Application->ProcessMessages();
// 修正需要下载的字节数，使得dwRequest + dwCount<dwTotal
if(dwTotal>0) // dwTotal<=0表示下载到文件结束
{
if(dwRequest+dwCount>dwTotal)
dwRequest=dwTotal-dwCount;
}
bool ReadReturn = InternetReadFile(FhRequest,
(LPVOID)Buffer,
dwRequest,
&dwRead);
if(!ReadReturn)break;
if(dwRead==0)break;
// 保存数据
Buffer[dwRead]='\0';
FileWrite(iFileHandle, Buffer, dwRead);
dwCount = dwCount + dwRead;
// 发出下载进程事件
DoOnProgress(dwCount);
if(dwTotal>0) // Count<=0表示下载到文件结束
{
if(dwCount>=dwTotal)break;
}
}
}catch(Exception &exception)
{
DoOnStatusText(exception.Message);
}
FileClose(iFileHandle);
DoOnStatusText("End：InternetReadFile");
if(dwCount==dwTotal)FSuccess=true;
}
//---------------------------------------------------------------------------
// 关闭Internet句柄
void THttpGetThread::EndHttpGet(void)
{
if(FConnected)
{
DoOnStatusText("Closing:InternetConnect");
try
{
InternetCloseHandle(FhRequest);
InternetCloseHandle(FhConnect);
InternetCloseHandle(FhSession);
}catch(...){}
FhSession=NULL;
FhConnect=NULL;
FhRequest=NULL;
FConnected=false;
DoOnStatusText("Closed:InternetConnect");
}
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
void THttpGetThread::DoOnGetFileSize(int Size)
{
if(FOnGetFileSize)
FOnGetFileSize(FOwner,Size);
}
//---------------------------------------------------------------------------
void THttpGetThread::DoOnProgress(int Position)
{
if(FOnProgress)
FOnProgress(FOwner,Position,dwTotal,FIndex);
}
//---------------------------------------------------------------------------
void THttpGetThread::DoOnStatusText(AnsiString Text)
{
if(FOnStatusText)
FOnStatusText(FOwner,Text,FIndex);
}
//---------------------------------------------------------------------------
void THttpGetThread::DoOnComplete(void)
{
if(FOnComplete)
FOnComplete(FOwner,FIndex);
}
//---------------------------------------------------------------------------
void THttpGetThread::DoOnError(void)
{
if(FOnError)
FOnError(FOwner,FIndex);
}
//---------------------------------------------------------------------------