如何使用HTTP写一个下载文件的函数（Indy、NM或直接写都可）(100分)

本人正急于写一个使用HTTP实现下载文件的函数（Indy、NM或直接写都可），请大家帮助

给你一段代码好了。[]

{*************************************************************}
{ HTTPGet component for Delphi 32 }
{ Version: 1.94 }
{ E-Mail: info@utilmind.com }
{ WWW: http://www.utilmind.com }
{ Created: October 19, 1999 }
{ Modified: June 6, 2000 }
{ Legal: Copyright (c) 1999-2000, UtilMind Solutions }
{*************************************************************}
{ PROPERTIES: }
{ Agent: String - User Agent }
{ }
{* BinaryData: Boolean - This setting specifies which type }
{* of data will taken from the web. }
{* If you set this property TRUE then }
{* component will determinee the size }
{* of files *before* getting them from }
{* the web. }
{* If this property is FALSE then as we}
{* do not knows the file size the }
{* OnProgress event will doesn't work. }
{* Also please remember that is you set}
{* this property as TRUE you will not }
{* capable to get from the web ASCII }
{* data and ofter got OnError event. }
{ }
{ FileName: String - Path to local file to store the data }
{ taken from the web }
{ Password, UserName - set this properties if you trying to }
{ get data from password protected }
{ directories. }
{ Referer: String - Additional data about referer document }
{ URL: String - The url to file or document }
{ UseCache: Boolean - Get file from the Internet Explorer's }
{ cache if requested file is cached. }
{*************************************************************}
{ METHODS: }
{ GetFile - Get the file from the web specified in the URL }
{ property and store it to the file specified in }
{ the FileName property }
{ GetString - Get the data from web and return it as usual }
{ String. You can receive this string hooking }
{ the OnDoneString event. }
{ Abort - Stop the current session }
{*************************************************************}
{ EVENTS: }
{ OnDoneFile - Occurs when the file is downloaded }
{ OnDoneString - Occurs when the string is received }
{ OnError - Occurs when error happend }
{ OnProgress - Occurs at the receiving of the BINARY DATA }
{*************************************************************}
{ Please see demo program for more information. }
{*************************************************************}
{ IMPORTANT NOTE: }
{ This software is provided 'as-is', without any express or }
{ implied warranty. In no event will the author be held }
{ liable for any damages arising from the use of this }
{ software. }
{ Permission is granted to anyone to use this software for }
{ any purpose, including commercial applications, and to }
{ alter it and redistribute it freely, subject to the }
{ following restrictions: }
{ 1. The origin of this software must not be misrepresented, }
{ you must not claim that you wrote the original software. }
{ If you use this software in a product, an acknowledgment }
{ in the product documentation would be appreciated but is }
{ not required. }
{ 2. Altered source versions must be plainly marked as such, }
{ and must not be misrepresented as being the original }
{ software. }
{ 3. This notice may not be removed or altered from any }
{ source distribution. }
{*************************************************************}

unit HTTPGet;

interface

uses
Windows, Messages, SysUtils, Classes, WinInet;

type
TOnProgressEvent = procedure(Sender: TObject; TotalSize, Readed: Integer) of object;
TOnDoneFileEvent = procedure(Sender: TObject; FileName: String; FileSize: Integer) of object;
TOnDoneStringEvent = procedure(Sender: TObject; Result: String) of object;

THTTPGetThread = class(TThread)
private
FTAcceptTypes,
FTAgent,
FTURL,
FTFileName,
FTStringResult,
FTUserName,
FTPassword,
FTPostQuery,
FTReferer: String;
FTBinaryData,
FTUseCache: Boolean;

FTResult: Boolean;
FTFileSize: Integer;
FTToFile: Boolean;

BytesToRead, BytesReaded: DWord;

FTProgress: TOnProgressEvent;

procedure UpdateProgress;
protected
procedure Execute; override;
public
constructor Create(aAcceptTypes, aAgent, aURL, aFileName, aUserName, aPassword, aPostQuery, aReferer: String;
aBinaryData, aUseCache: Boolean; aProgress: TOnProgressEvent; aToFile: Boolean);
end;

THTTPGet = class(TComponent)
private
FAcceptTypes: String;
FAgent: String;
FBinaryData: Boolean;
FURL: String;
FUseCache: Boolean;
FFileName: String;
FUserName: String;
FPassword: String;
FPostQuery: String;
FReferer: String;
FWaitThread: Boolean;

FThread: THTTPGetThread;
FError: TNotifyEvent;
FResult: Boolean;

FProgress: TOnProgressEvent;
FDoneFile: TOnDoneFileEvent;
FDoneString: TOnDoneStringEvent;

procedure ThreadDone(Sender: TObject);
public
constructor Create(aOwner: TComponent); override;
destructor Destroy; override;

procedure GetFile;
procedure GetString;
procedure Abort;
published
property AcceptTypes: String read FAcceptTypes write FAcceptTypes;
property Agent: String read FAgent write FAgent;
property BinaryData: Boolean read FBinaryData write FBinaryData;
property URL: String read FURL write FURL;
property UseCache: Boolean read FUseCache write FUseCache;
property FileName: String read FFileName write FFileName;
property UserName: String read FUserName write FUserName;
property Password: String read FPassword write FPassword;
property PostQuery: String read FPostQuery write FPostQuery;
property Referer: String read FReferer write FReferer;
property WaitThread: Boolean read FWaitThread write FWaitThread;

property OnProgress: TOnProgressEvent read FProgress write FProgress;
property OnDoneFile: TOnDoneFileEvent read FDoneFile write FDoneFile;
property OnDoneString: TOnDoneStringEvent read FDoneString write FDoneString;
property OnError: TNotifyEvent read FError write FError;
end;

procedure Register;

implementation

// THTTPGetThread

constructor THTTPGetThread.Create(aAcceptTypes, aAgent, aURL, aFileName, aUserName, aPassword, aPostQuery, aReferer: String;
aBinaryData, aUseCache: Boolean; aProgress: TOnProgressEvent; aToFile: Boolean);
begin
FreeOnTerminate := True;
inherited Create(True);

FTAcceptTypes := aAcceptTypes;
FTAgent := aAgent;
FTURL := aURL;
FTFileName := aFileName;
FTUserName := aUserName;
FTPassword := aPassword;
FTPostQuery := aPostQuery;
FTReferer := aReferer;
FTProgress := aProgress;
FTBinaryData := aBinaryData;
FTUseCache := aUseCache;

FTToFile := aToFile;
Resume;
end;

procedure THTTPGetThread.UpdateProgress;
begin
FTProgress(Self, FTFileSize, BytesReaded);
end;

procedure THTTPGetThread.Execute;
var
hSession, hConnect, hRequest: hInternet;
HostName, FileName: String;
f: File;
Buf: Pointer;
dwBufLen, dwIndex: DWord;
Data: Array[0..$400] of Char;
TempStr: String;
RequestMethod: PChar;
InternetFlag: DWord;
AcceptType: LPStr;

procedure ParseURL(URL: String; var HostName, FileName: String);

procedure ReplaceChar(c1, c2: Char; var St: String);
var
p: Integer;
begin
while True do
begin
p := Pos(c1, St);
if p = 0 then Break
else St[p] := c2;
end;
end;

var
i: Integer;
begin
if Pos('http://', LowerCase(URL)) <> 0 then
System.Delete(URL, 1, 7);

i := Pos('/', URL);
HostName := Copy(URL, 1, i);
FileName := Copy(URL, i, Length(URL) - i + 1);

if (Length(HostName) > 0) and (HostName[Length(HostName)] = '/') then
SetLength(HostName, Length(HostName) - 1);
end;

procedure CloseHandles;
begin
InternetCloseHandle(hRequest);
InternetCloseHandle(hConnect);
InternetCloseHandle(hSession);
end;

begin
try
ParseURL(FTURL, HostName, FileName);

if Terminated then
begin
FTResult := False;
Exit;
end;

if FTAgent <> '' then
hSession := InternetOpen(PChar(FTAgent),
INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0)
else
hSession := InternetOpen(nil,
INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);

hConnect := InternetConnect(hSession, PChar(HostName),
INTERNET_DEFAULT_HTTP_PORT, PChar(FTUserName), PChar(FTPassword), INTERNET_SERVICE_HTTP, 0, 0);

if FTPostQuery = '' then RequestMethod := 'GET'
else RequestMethod := 'POST';

if FTUseCache then InternetFlag := 0
else InternetFlag := INTERNET_FLAG_RELOAD;

AcceptType := PChar('Accept: ' + FTAcceptTypes);
hRequest := HttpOpenRequest(hConnect, RequestMethod, PChar(FileName), 'HTTP/1.0',
PChar(FTReferer), @AcceptType, InternetFlag, 0);

if FTPostQuery = '' then
HttpSendRequest(hRequest, nil, 0, nil, 0)
else
HttpSendRequest(hRequest, 'Content-Type: application/x-www-form-urlencoded', 47,
PChar(FTPostQuery), Length(FTPostQuery));

if Terminated then
begin
CloseHandles;
FTResult := False;
Exit;
end;

dwIndex := 0;
dwBufLen := 1024;
GetMem(Buf, dwBufLen);

FTResult := HttpQueryInfo(hRequest, HTTP_QUERY_CONTENT_LENGTH,
Buf, dwBufLen, dwIndex);

if Terminated then
begin
FreeMem(Buf);
CloseHandles;
FTResult := False;
Exit;
end;

if FTResult or not FTBinaryData then
begin
if FTResult then
FTFileSize := StrToInt(StrPas(Buf));

BytesReaded := 0;

if FTToFile then
begin
AssignFile(f, FTFileName);
Rewrite(f, 1);
end
else FTStringResult := '';

while True do
begin
if Terminated then
begin
if FTToFile then CloseFile(f);
FreeMem(Buf);
CloseHandles;

FTResult := False;
Exit;
end;

if not InternetReadFile(hRequest, @Data, SizeOf(Data), BytesToRead) then Break
else
if BytesToRead = 0 then Break
else
begin
if FTToFile then
BlockWrite(f, Data, BytesToRead)
else
begin
TempStr := Data;
SetLength(TempStr, BytesToRead);
FTStringResult := FTStringResult + TempStr;
end;

inc(BytesReaded, BytesToRead);
if Assigned(FTProgress) then
Synchronize(UpdateProgress);
end;
end;

if FTToFile then
FTResult := FTFileSize = Integer(BytesReaded)
else
begin
SetLength(FTStringResult, BytesReaded);
FTResult := BytesReaded <> 0;
end;

if FTToFile then CloseFile(f);
end;

FreeMem(Buf);

CloseHandles;
except
end;
end;

// HTTPGet

constructor THTTPGet.Create(aOwner: TComponent);
begin
inherited Create(aOwner);
FAcceptTypes := '*/*';
FAgent := 'UtilMind HTTPGet';
end;

destructor THTTPGet.Destroy;
begin
Abort;
inherited Destroy;
end;

procedure THTTPGet.GetFile;
var
Msg: TMsg;
begin
if not Assigned(FThread) then
begin
FThread := THTTPGetThread.Create(FAcceptTypes, FAgent, FURL, FFileName, FUserName, FPassword, FPostQuery, FReferer,
FBinaryData, FUseCache, FProgress, True);
FThread.OnTerminate := ThreadDone;
if FWaitThread then
while Assigned(FThread) do
while PeekMessage(Msg, 0, 0, 0, PM_REMOVE) do
begin
TranslateMessage(Msg);
DispatchMessage(Msg);
end;
end
end;

procedure THTTPGet.GetString;
var
Msg: TMsg;
begin
if not Assigned(FThread) then
begin
FThread := THTTPGetThread.Create(FAcceptTypes, FAgent, FURL, FFileName, FUserName, FPassword, FPostQuery, FReferer,
FBinaryData, FUseCache, FProgress, False);
FThread.OnTerminate := ThreadDone;
if FWaitThread then
while PeekMessage(Msg, 0, 0, 0, PM_REMOVE) do
begin
TranslateMessage(Msg);
DispatchMessage(Msg);
end;
end
end;

procedure THTTPGet.Abort;
begin
if Assigned(FThread) then
begin
FThread.Terminate;
FThread.FTResult := False;
end;
end;

procedure THTTPGet.ThreadDone(Sender: TObject);
begin
FResult := FThread.FTResult;
if FResult then
if FThread.FTToFile then
if Assigned(FDoneFile) then FDoneFile(Self, FThread.FTFileName, FThread.FTFileSize) else
else
if Assigned(FDoneString) then FDoneString(Self, FThread.FTStringResult) else
else
if Assigned(FError) then FError(Self);
FThread := nil;
end;

procedure Register;
begin
RegisterComponents('Internet', [THTTPGet]);
end;

end.

请问使用方法
举个例子，谢谢

Sorry, 要下班了。
看看前面的介绍，应当容易试出来的。

谢谢！