相对完整的多线程idhttp文件下载代码

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, forms,
Dialogs, ComCtrls, StdCtrls, IdComponent, IdTCPConnection, IdTCPClient,
IdHTTP, IdBaseComponent, IdAntiFreezeBase, IdAntiFreeze,
IdThreadComponent, IdFTP ,IdException;
type
MyException1 = class(exception)//自定义的异常类
end;

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;
Label1: TLabel;
Label2: TLabel;
Button2: TButton;
Button3: TButton;
ListBox1: TListBox;
Edit1: TEdit;
Edit2: TEdit;
Label3: TLabel;
Label4: TLabel;
Label5: TLabel;
SaveDialog1: TSaveDialog;

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;
time1, time2: TDateTime;
MyThread: array[1..10] of TThread;
procedure GetThread();
procedure AddFile();
procedure NewAddFile();
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
//savedialog1.
try
time1 := Now;
tcount := 0;
aURL := Edit1.Text; //下载地址
if aURL = '' then
begin
MessageDlg('请输入下载地址！',mtError,[mbOK],0);
Exit;
end;
aFile := GetURLFileName(Edit1.Text); //得到文件名
savedialog1.FileName :=afile;
if savedialog1.Execute then


if Edit2.Text = '' then
begin
case MessageDlg('请输入线程数，最大支持10个线程，默认为单线程下载！', mtConfirmation, [mbYes, mbNo], 0) of
mrYes: nn:=1; //默认
mrNo: Exit; //重新输入
end;
end
else
nn := StrToInt(Edit2.Text); //线程数
if nn > 10 then
begin
raise MyException1.Create('输入超过线程限制数，请重新输入！');
end;
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;
except
on E:EConvertError do//捕捉内建的Econverterror异常
begin
//ShowMessage('请输入数字');
MessageDlg('请输入数字'+#13,mtError,[mbOK],0);
Exit;
end;
on E:MyException1 do//捕捉自定义的MyException异常
begin
MessageDlg(E.Message,mtError,[mbOK],0);
Edit2.Text:= '';
Exit;
end;
on E:EIdSocketError do//捕捉内建的EIdSocketError异常
begin
MessageDlg('连接不上服务器，或服务起未开启！',mtError,[mbOK],0);
Exit;
end;
on E:EIdConnectException do//捕捉内建的EIdSocketError异常
begin
MessageDlg('连接不上服务器，或服务起未开启！',mtError,[mbOK],0);
Exit;
end;
on E:EIdHTTPProtocolException do//捕捉内建的EIdSocketError异常
begin
MessageDlg('目标文件找不到！',mtError,[mbOK],0);
Exit;
end;
else
raise //reraise其他异常

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 := true;
ProgressBar1.Max := AWorkCountMax;
ProgressBar1.Min := 0;
ProgressBar1.Position := 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.Position := AWorkCount;
//ProgressBar1.Position:=ProgressBar1.Position+AWorkCount; //*******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);
var
i : integer;
begin
try
if AbortTransfer then
begin
i:=1;
while i <= nn do
begin
MyThread[i].Suspend;
i := i + 1;
end;
AbortTransfer := false;
button2.Caption:='开始';
end else
begin
i:=1;
while i <= nn do
begin
MyThread[i].Resume;
i := i + 1;
end;
AbortTransfer := True;
button2.Caption:='暂停';
end;
except
on E:EThread do
begin
end;
else
raise //reraise其他异常
end;
//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;
IdHTTP1.DisconnectSocket;
form1.close;

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
try
i := 1;
mStream1 := TMemoryStream.Create;
mStream2 := TMemoryStream.Create;

mStream1.loadfromfile(afile + '1');
while i < nn do
begin
mStream2.loadfromfile(afile + IntToStr(i + 1));
mStream1.seek(mStream1.size, soFromBeginning);
mStream1.copyfrom(mStream2, mStream2.size);
mStream2.clear;
i := i + 1;
end;
FreeAndNil(mStream2);
mStream1.SaveToFile(afile);
FreeAndNil(mStream1);
//删除临时文件
i:=1;
while i <= nn do
begin
deletefile(afile + IntToStr(i));
i := i + 1;
end;
form1.ListBox1.ItemIndex := form1.ListBox1.Items.Add('下载成功');
except
i:=1;
while i <= nn do
begin
if FileExists(aFile+inttostr(i)) then
deletefile(afile + IntToStr(i));
i := i + 1;
end;
ShowMessage('下载文件出错，临时文件已删除，请重新下载！')
end;

end;

procedure Tform1.NewAddFile(); //合并文件
var
i: Integer;
InStream, OutStream : TFileStream;
SourceFile : String;
begin
try
i := 1;
OutStream:=TFileStream.Create(aFile,fmCreate);
//OutStream:=TFileStream.Create(('D\1\'+aFile),fmCreate); //此句与savedialog冲突，发生异常，使savedialog指定路径无效。
while i <= nn do
begin
SourceFile := afile + IntToStr(i);
InStream:=TFileStream.Create(SourceFile, fmOpenRead);
OutStream.CopyFrom(InStream,0);
FreeAndNil(InStream);
i:= i+1;
end;
FreeAndNil(OutStream);
//删除临时文件
i:=1;
while i <= nn do
begin
deletefile(afile + IntToStr(i));
i := i + 1;
end;

except
i:=1;
while i <= nn do
begin
if FileExists(aFile+inttostr(i)) then
deletefile(afile + IntToStr(i));
i := i + 1;
end;
end;
if FileExists(aFile) then
begin
FreeAndNil(OutStream);
InStream := TFileStream.Create(aFile, fmOpenWrite);
if InStream.Size < aFileSize then
begin
FreeAndNil(InStream);
deletefile(afile);
//ShowMessage('下载文件出错，临时文件已删除，请重新下载！')
form1.ListBox1.ItemIndex := form1.ListBox1.Items.Add('下载文件出错，临时文件已删除，请重新下载！');
end
else
begin
FreeAndNil(InStream);
form1.ListBox1.ItemIndex := form1.ListBox1.Items.Add('下在成功');
end;
end;



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
///try
temhttp.Get(tURL, tStream); //开始下载
except
if FileExists(temFileName) then
begin
freeandnil(tstream);
deletefile(temFileName);//本来想用来删除未下完的文件，可惜不成功，有的线程没有删除，只有部分删除了，
//不过这样导致后面合并文件时出错，同样也可以把临时文件删除。
//ShowMessage('下载文件出错，临时文件已删除，请重新下载！');/
end;
temhttp.Disconnect;
end;

form1.ListBox1.ItemIndex := form1.ListBox1.Items.Add(temFileName +
'download');

//finally
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
form1.ListBox1.ItemIndex := form1.ListBox1.Items.Add('正在合并删除临时文件');
form1.NewAddFile;
form1.time2 := Now;
form1.Label5.Caption := formatDateTime ('n:ss', form1.Time2-form1.Time1) + ' seconds';
end;

end;

end.