Delphi程序運行於Windows平台，利用Windows平台的API可實現很多功能，今天這個調用Windows API下載文件的例子就是其中之一，調用win的API可簡化我們的Delphi代碼，必竟我們要依靠微軟嘛，所以有興趣的朋友，不妨參考下下面這個Delphi下載文件的代碼：
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unit Unit1;
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interface
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uses
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Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
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Dialogs, WinInet, StdCtrls;
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type
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TForm1 = class(TForm)
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Button1: TButton;
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Memo1: TMemo;
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Button2: TButton;
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procedure Button1Click(Sender: TObject);
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procedure Button2Click(Sender: TObject);
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private
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{ Private declarations }
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public
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{ Public declarations }
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end;
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var
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Form1: TForm1;
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implementation
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{$R *.dfm}
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function DownloadToString(const Url: string): string;
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var
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NetHandle: HINTERNET;
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UrlHandle: HINTERNET;
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Buffer: array[0..1024] of Char;
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BytesRead: dWord;
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begin
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Result := '';
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NetHandle := InternetOpen('Delphi 5.x', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
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if Assigned(NetHandle) then
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begin
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UrlHandle := InternetOpenUrl(NetHandle, PChar(Url), nil, 0, INTERNET_FLAG_RELOAD, 0);
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if Assigned(UrlHandle) then
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{ UrlHandle valid? Proceed with download }
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begin
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FillChar(Buffer, SizeOf(Buffer), 0);
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repeat
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Result := Result + Buffer;
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FillChar(Buffer, SizeOf(Buffer), 0);
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InternetReadFile(UrlHandle, @Buffer, SizeOf(Buffer), BytesRead);
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until BytesRead = 0;
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InternetCloseHandle(UrlHandle);
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end
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else
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{ UrlHandle is not valid. Raise an exception. }
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raise Exception.CreateFmt('Cannot open URL %s', [Url]);
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InternetCloseHandle(NetHandle);
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end
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else
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{ NetHandle is not valid. Raise an exception }
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raise Exception.Create('Unable to initialize Wininet');
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end;
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function DownloadToFile(const Url, LFile: string): Boolean;
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var
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NetHandle: HINTERNET;
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UrlHandle: HINTERNET;
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Buffer: array[0..1024] of Char;
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BytesRead: dWord;
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LFileStream: TFileStream;
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begin
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Result := False;
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NetHandle := InternetOpen('Delphi 5.x', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
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if Assigned(NetHandle) then
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begin
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UrlHandle := InternetOpenUrl(NetHandle, PChar(Url), nil, 0, INTERNET_FLAG_RELOAD, 0);
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if Assigned(UrlHandle) then
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{ UrlHandle valid? Proceed with download }
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begin
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LFileStream := TFileStream.Create(LFile, fmCreate);
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FillChar(Buffer, SizeOf(Buffer), 0);
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repeat
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FillChar(Buffer, SizeOf(Buffer), 0);
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InternetReadFile(UrlHandle, @Buffer, SizeOf(Buffer), BytesRead);
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LFileStream.Write(Buffer, BytesRead);
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until BytesRead = 0;
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LFileStream.Free;
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InternetCloseHandle(UrlHandle);
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end
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else
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{ UrlHandle is not valid. Raise an exception. }
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raise Exception.CreateFmt('Cannot open URL %s', [Url]);
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InternetCloseHandle(NetHandle);
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end
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else
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{ NetHandle is not valid. Raise an exception }
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raise Exception.Create('Unable to initialize Wininet');
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end;
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procedure TForm1.Button1Click(Sender: TObject);
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begin
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Memo1.Lines.Text := DownloadToString('http://down.360safe.com/')
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end;
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procedure TForm1.Button2Click(Sender: TObject);
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begin
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DownloadToFile('http://down.360safe.com/inst.exe', 'mailsextractor.exe');//此地址可改，只是測試用的，改成你的實際地址
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end;
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end.
例子簡單，僅供參考，高手莫笑哦~
