IdHTTP多线程下载
unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, ComCtrls, StdCtrls, IdComponent, IdTCPConnection, IdTCPClient,
IdHTTP, IdBaseComponent, IdAntiFreezeBase, IdAntiFreeze,
IdThreadComponent, IdFTP;

type
TThread1 = class(TThread)

private
fCount, tstart, tlast: integer;
tURL, tFile, temFileName: string;
tResume: Boolean;
tStream: TFileStream;
protected
procedure Execute; override;
public
constructor create1(aURL, aFile, fileName: string; bResume: Boolean; Count,
start, last: integer);
procedure DownLodeFile(); //下载文件
end;

type
TForm1 = class(TForm)
IdAntiFreeze1: TIdAntiFreeze;
IdHTTP1: TIdHTTP;
Button1: TButton;
ProgressBar1: TProgressBar;
IdThreadComponent1: TIdThreadComponent;
Label1: TLabel;
Label2: TLabel;
Button2: TButton;
Button3: TButton;
ListBox1: TListBox;
Edit1: TEdit;
Edit2: TEdit;
Label3: TLabel;
Label4: TLabel;

procedure Button1Click(Sender: TObject);
procedure IdHTTP1WorkBegin(Sender: TObject; AWorkMode: TWorkMode;
const AWorkCountMax: Integer);
procedure IdHTTP1Work(Sender: TObject; AWorkMode: TWorkMode;
const AWorkCount: Integer);
procedure Button2Click(Sender: TObject);
procedure IdHTTP1Status(ASender: TObject; const AStatus: TIdStatus;
const AStatusText: string);
procedure Button3Click(Sender: TObject);
private
public
nn, aFileSize, avg: integer;
MyThread: array[1..10] of TThread;
procedure GetThread();
procedure AddFile();
function GetURLFileName(aURL: string): string;
function GetFileSize(aURL: string): integer;
end;

var
Form1: TForm1;

implementation
var
AbortTransfer: Boolean;
aURL, aFile: string;

tcount: integer; //检查文件是否全部下载完毕
{$R *.dfm}

//get FileName

function TForm1.GetURLFileName(aURL: string): string;
var
i: integer;
s: string;
begin //返回下载地址的文件名

s := aURL;
i := Pos('/', s);
while i <> 0 do //去掉"/"前面的内容剩下的就是文件名了
begin
Delete(s, 1, i);
i := Pos('/', s);
end;
Result := s;
end;

//get FileSize

function TForm1.GetFileSize(aURL: string): integer;
var
FileSize: integer;
begin
IdHTTP1.Head(aURL);
FileSize := IdHTTP1.Response.ContentLength;
IdHTTP1.Disconnect;
Result := FileSize;
end;

//执行下载

procedure TForm1.Button1Click(Sender: TObject);
var
j: integer;
begin
tcount := 0;
Showmessage('OK!主线程在执行，获得文件名并显示在Edit2中');
aURL := Edit1.Text; //下载地址
aFile := GetURLFileName(Edit1.Text); //得到文件名
nn := StrToInt(Edit2.Text); //线程数
j := 1;
aFileSize := GetFileSize(aURL);
avg := trunc(aFileSize / nn);
begin
try
GetThread();
while j <= nn do
begin
MyThread[j].Resume; //唤醒线程
j := j + 1;
end;
except
Showmessage('创建线程失败!');
Exit;
end;
end;
end;

//开始下载前,将ProgressBar1的最大值设置为需要接收的数据大小.

procedure TForm1.IdHTTP1WorkBegin(Sender: TObject; AWorkMode: TWorkMode;
const AWorkCountMax: Integer);
begin
AbortTransfer := False;
ProgressBar1.Max := AWorkCountMax;
ProgressBar1.Min := 0;
ProgressBar1. 0;
end;

//接收数据的时候,进度将在ProgressBar1显示出来.

procedure TForm1.IdHTTP1Work(Sender: TObject; AWorkMode: TWorkMode;
const AWorkCount: Integer);
begin
if AbortTransfer then
begin
IdHTTP1.Disconnect; //中断下载
end;
ProgressBar1. AWorkCount;
//ProgressBar1.; //*******显示速度极快
Application.ProcessMessages;
//***********************************这样使用不知道对不对

end;

//中断下载

procedure TForm1.Button2Click(Sender: TObject);
begin
AbortTransfer := True;
IdHTTP1.Disconnect;
end;

//状态显示

procedure TForm1.IdHTTP1Status(ASender: TObject; const AStatus: TIdStatus;
const AStatusText: string);
begin
ListBox1.ItemIndex := ListBox1.Items.Add(AStatusText);
end;

//退出程序

procedure TForm1.Button3Click(Sender: TObject);
begin
application.Terminate;

end;

//循环产生线程

procedure TForm1.GetThread();
var
i: integer;
start: array[1..100] of integer;
last: array[1..100] of integer; //改用了数组，也可不用
fileName: string;
begin
i := 1;
while i <= nn do
begin
start[i] := avg * (i - 1);
last[i] := avg * i -1; //这里原先是last:=avg*i;
if i = nn then
begin
last[i] := avg*i + aFileSize-avg*nn; //这里原先是aFileSize
end;
fileName := aFile + IntToStr(i);
MyThread[i] := TThread1.create1(aURL, aFile, fileName, false, i, start[i],
last[i]);
i := i + 1;
end;
end;

procedure TForm1.AddFile(); //合并文件
var
mStream1, mStream2: TMemoryStream;
i: integer;
begin
i := 1;
mStream1 := TMemoryStream.Create;
mStream2 := TMemoryStream.Create;

mStream1.loadfromfile('设备工程进度管理前期规划.doc' + '1');
while i < nn do
begin
mStream2.loadfromfile('设备工程进度管理前期规划.doc' + IntToStr(i + 1));
mStream1.seek(mStream1.size, soFromBeginning);
mStream1.copyfrom(mStream2, mStream2.size);
mStream2.clear;
i := i + 1;
end;
mStream2.free;
mStream1.SaveToFile('设备工程进度管理前期规划.doc');
mStream1.free;
//删除临时文件
i:=1;
while i <= nn do
begin
deletefile('设备工程进度管理前期规划.doc' + IntToStr(i));
i := i + 1;
end;
Form1.ListBox1.ItemIndex := Form1.ListBox1.Items.Add('下在成功');

end;

//构造函数

constructor TThread1.create1(aURL, aFile, fileName: string; bResume: Boolean;
Count, start, last: integer);
begin
inherited create(true);
FreeOnTerminate := true;
tURL := aURL;
tFile := aFile;
fCount := Count;
tResume := bResume;
tstart := start;
tlast := last;
temFileName := fileName;
end;
//下载文件函数

procedure TThread1.DownLodeFile();
var
temhttp: TIdHTTP;
begin

temhttp := TIdHTTP.Create(nil);
temhttp.onWorkBegin := Form1.IdHTTP1WorkBegin;
temhttp.onwork := Form1.IdHTTP1work;
temhttp.onStatus := Form1.IdHTTP1Status;
Form1.IdAntiFreeze1.OnlyWhenIdle := False; //设置使程序有反应.
if FileExists(temFileName) then //如果文件已经存在
tStream := TFileStream.Create(temFileName, fmOpenWrite)
else
tStream := TFileStream.Create(temFileName, fmCreate);

if tResume then //续传方式
begin
exit;
end
else //覆盖或新建方式
begin
temhttp.Request.ContentRangeStart := tstart;
temhttp.Request.ContentRangeEnd := tlast;
end;

try
temhttp.Get(tURL, tStream); //开始下载
Form1.ListBox1.ItemIndex := Form1.ListBox1.Items.Add(temFileName +
'download');

finally
//tStream.Free;
freeandnil(tstream);
temhttp.Disconnect;
end;

end;

procedure TThread1.Execute;
begin
if Form1.Edit1.Text <> '' then
//synchronize(DownLodeFile)
DownLodeFile
else
exit;
inc(tcount);
if tcount = Form1.nn then //当tcount=nn时代表全部下载成功
begin
//Showmessage('全部下载成功!');
Form1.ListBox1.ItemIndex := Form1.ListBox1.Items.Add('正在合并删除临时文件');
Form1.AddFile;
end;
end;

end.