1 unit Unit3;
2
3 interface
4
5 uses
6 Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
7 Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, System.Net.HttpClient,
8 Vcl.ComCtrls;
9
10 type
11 TForm3 = class(TForm)
12 btnStart: TButton;
13 ProgressBar1: TProgressBar;
14 edt1: TEdit;
15 procedure btnStartClick(Sender: TObject);
16 procedure FormCloseQuery(Sender: TObject; var CanClose: Boolean);
17 procedure FormShow(Sender: TObject);
18 procedure FormCreate(Sender: TObject);
19 private
20 { Private declarations }
21
22 /// <summary>
23 /// 下载的时候不允许关闭窗体
24 /// </summary>
25 FAllowFormClose: Boolean;
26
27 /// <summary>
28 /// 接收数据事件
29 /// </summary>
30 procedure ReceiveDataEvent(const Sender: TObject; AContentLength: Int64; AReadCount: Int64; var Abort: Boolean);
31 public
32 { Public declarations }
33 end;
34
35 var
36 Form3: TForm3;
37
38 implementation
39
40 {$R *.dfm}
41
42 procedure TForm3.ReceiveDataEvent(const Sender: TObject; AContentLength: Int64; AReadCount: Int64; var Abort: Boolean);
43 begin
44 //Queue运行在主线程中,且是异步的。
45 TThread.Queue(nil,
46 procedure
47 begin
48 ProgressBar1.Position := AReadCount;
49 end);
50 end;
51
52 procedure TForm3.btnStartClick(Sender: TObject);
53 begin
54 //创建一个普通线程,防止界面假死.
55 TThread.CreateAnonymousThread(
56 procedure
57 var
58 MyHTTPClient: THTTPClient;
59 MyHTTPResponse: IHTTPResponse;
60 MyMemoryStream: TMemoryStream;
61 downloadUrl: string;
62 begin
63 MyHTTPClient := THTTPClient.Create;
64 MyMemoryStream := TMemoryStream.Create;
65 try
66 btnStart.Enabled := False;
67 FAllowFormClose := False;
68 downloadUrl := Trim(edt1.Text);
69
70 //获取文件的大小
71 MyHTTPResponse := MyHTTPClient.Head(downloadUrl);
72 ProgressBar1.Position := 0;
73 ProgressBar1.Max := MyHTTPResponse.ContentLength;
74
75 //开始下载,保存到本地
76 MyHTTPClient.OnReceiveData := ReceiveDataEvent;
77 MyHTTPResponse := MyHTTPClient.Get(downloadUrl, MyMemoryStream);
78 if MyHTTPResponse.StatusCode = 200 then
79 begin
80 MyMemoryStream.SaveToFile('c:\aa.exe');
81 ShowMessage('下载完成');
82 end;
83 finally
84 MyHTTPClient.Free;
85 MyMemoryStream.Free;
86 //最终都允许关闭窗体
87 btnStart.Enabled := True;
88 FAllowFormClose := True;
89 end;
90 end).Start;
91 end;
92
93 procedure TForm3.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
94 begin
95 CanClose := FAllowFormClose;
96 end;
97
98 procedure TForm3.FormCreate(Sender: TObject);
99 begin
100 ReportMemoryLeaksOnShutdown := True;
101 end;
102
103 procedure TForm3.FormShow(Sender: TObject);
104 begin
105 btnStart.Enabled := True;
106 FAllowFormClose := True;
107 ProgressBar1.Position := 0;
108 end;
109
110 end.
111
11
