[英]idhttp - get response string while loading page
在页面加载之前,我需要获取接收的字符串(以用于asterix http AMI事件)。 所以我试图访问idHttp的OnWork事件中的接收到的字符串,但出现错误:
var
Form2: TForm2;
s:TStringStream;
procedure TForm2.Button1Click(Sender: TObject);
begin
s:=TStringStream.Create;
idhttp1.Get('http://website.com:8088/asterisk/rawman?action=waitevent&timeout=10',s);
showmessage(s.DataString); //NO ERROR
end;
procedure TForm2.IdHTTP1Work(ASender: TObject; AWorkMode: TWorkMode;
AWorkCount: Int64);
begin
showmessage(s.DataString); //ERROR HERE
end;
更新:我按照Remy Lebeau的建议创建了自定义类(TAMIStringStream),但仍然出现错误。 我做错什么了吗?
unit Unit2;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, IdBaseComponent, IdComponent,
IdTCPConnection, IdTCPClient, IdHTTP, cxGraphics, cxControls, cxLookAndFeels,
cxLookAndFeelPainters, cxContainer, cxEdit, Vcl.StdCtrls, cxTextEdit, cxMemo,
cxCheckBox;
type
TAMIStringStream = class(TStringStream)
FEncoding: TEncoding;
public
ReceivedSTR:string;
function Write(const Buffer; Count: Longint): Longint; override;
end;
TForm2 = class(TForm)
IdHTTP1: TIdHTTP;
Button1: TButton;
cxCheckBox1: TcxCheckBox;
Memo1: TMemo;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form2: TForm2;
s:TAMIStringStream;
implementation
{$R *.dfm}
function TAMIStringStream.Write(const Buffer; Count: Longint): Longint;
var t:string;
begin
Inherited;
t := FEncoding.GetString(Bytes, Position - Count, Count);
form2.memo1.lines.add(t);
ReceivedSTR := ReceivedSTR + t;
end;
procedure TForm2.Button1Click(Sender: TObject);
begin
idhttp1.Get('http://website.com:8088/asterisk/rawman?action=login&username=1cami&secret=111');
s:=TAMIStringStream.Create;
while cxCheckBox1.Checked do begin
idhttp1.Get('http://website.com:8088/asterisk/rawman?action=waitevent&timeout=10',s);
end;
end;
end.
要获得仍由TIdHTTP
下载的服务器的HTTP响应数据,您需要编写自己的TStream
派生的类,该类重写虚拟TStream.Write()
方法,然后可以将该类的实例传递给AResponseContent
TIdHTTP.Get()
AResponseContent
参数。 您的Write()
方法可以在将数据“写入”到流中时对其进行处理(由于它是实时流式传输,因此可以按任意块处理该数据)。
否则,您将必须完全跳过TIdHTTP
并改为使用TIdTCPClient
,手动实现HTTP协议,以便完全控制读写。
“基于HTTP的AMI”协议文档(请参阅此和本 )显示了如何向AMI发送HTTP请求以及如何轮询事件(是的,使用HTTP时必须轮询事件)。 由于轮询直到事件被传递后才返回,因此没有太多理由在运行中读取服务器的响应数据。 TIdHTTP.Get()
将阻塞,直到接收到事件为止,然后您可以根据需要对其进行处理。 因此,如果没有自定义流,您的第一种方法应该会很好:
procedure TForm2.Button1Click(Sender: TObject);
var
s: TStringStream;
begin
idhttp1.Get('http://website.com:8088/asterisk/rawman?action=login&username=1cami&secret=111');
s := TStringStream.Create;
try
while cxCheckBox1.Checked do
begin
IdHttp1.Get('http://website.com:8088/asterisk/rawman?action=waitevent&timeout=10', s);
Memo1.Lines.Add(s.DataString);
s.Clear;
end;
finally
s.Free;
end;
end;
或者:
procedure TForm2.Button1Click(Sender: TObject);
var
s: String;
begin
idhttp1.Get('http://website.com:8088/asterisk/rawman?action=login&username=1cami&secret=111');
while cxCheckBox1.Checked do
begin
s := IdHttp1.Get('http://website.com:8088/asterisk/rawman?action=waitevent&timeout=10');
Memo1.Lines.Add(s);
end;
end;
由于TIdHTTP
的阻塞性质,我建议将轮询移到工作线程中:
procedure TMyThread.Execute;
var
http: TIdHTTP;
s: String;
begin
http := TIdHTTP.Create(nil);
try
http.Get('http://website.com:8088/asterisk/rawman?action=login&username=1cami&secret=111');
while not Terminated do
begin
s := http.Get('http://website.com:8088/asterisk/rawman?action=waitevent&timeout=10');
// do something...
end;
finally
http.Free;
end;
end;
如果HTTP轮询不适合您的需求,则应考虑使用“ AMI over TCP”(请参见this和this ),并为此使用TIdTCPClient
。 您可以使用计时器或线程来检查传入的数据。
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