我有一个像这样简单的http://issamsoft.com/app2/page1.aspx的Asp .net页面
我想向其中发布一些数据并从响应中提取数据,
通过使用TIdHttp。我试图像这样在Delphi2009中做到这一点:

Procedure TForm1.Button1Click(Sender: TObject);
Const
VIEWSTATE = '/wEPDwUKMjA3NjE4MDczNmRkSxPt/LdmgqMd+hN+hkbiqIZuGUk=';
EVENTVALIDATION = '/wEWAwL40NXEDALs0bLrBgKM54rGBtmtdOYy+U7IFq8B25bYT1d4o1iK';
FORMPARAMS = 'TextBox1=Issam&Button1=Button';
URL = 'http://issamsoft.com/app2/page1.aspx';
var
http: TIdHttp;
lstParams: TStringList;
begin
 http := TIdHTTP.Create(self);
 lstParams := TStringList.Create;
 try
  lstParams.Add('__VIEWSTATE='+VIEWSTATE);
  lstParams.Add('__EVENTVALIDATION='+EVENTVALIDATION);
  lstParams.Add(FORMPARAMS);
  http.Request.ContentType := 'application/x-www-form-urlencoded';
  Memo1.Lines.Text := http.Post(url,lstParams);
 finally
  http.Free;
  lstParams.Free;
 end;

end;

但是TIdhttp始终会给出错误(HTTP/1.1 500 Internal Server Error。)
我在idHttp单元中阅读了一些评论,讨论了HTTP协议(protocol)v 1.1这样的问题:



我的代码有问题吗?还是TidHttp Bug?如果问题出在
TIdHttp,有什么解决方法吗?还是有其他使用Indy组件的解决方案?

除了。我已经使用WebClient在C#中提出了一个解决方案,并且效果很好。
        private void button1_Click(object sender, EventArgs e)
    {
        WebClient myClient = new WebClient();
        string viewstate = HttpUtility.UrlEncodeUnicode(@"/wEPDwUKMjA3NjE4MDczNmRkSxPt/LdmgqMd+hN+hkbiqIZuGUk=");
        string eventvaildation = HttpUtility.UrlEncodeUnicode(@"/wEWAwL40NXEDALs0bLrBgKM54rGBtmtdOYy+U7IFq8B25bYT1d4o1iK");
        string postdata = "__VIEWSTATE=" + viewstate + "&" +
            "__EVENTVALIDATION=" + eventvaildation + "&TextBox1=Issam&Button1=Button";
        myClient.Headers.Add("Content-Type", "application/x-www-form-urlencoded");
        byte[] responce = myClient.UploadData("http://issamsoft.com/app2/page1.aspx", Encoding.ASCII.GetBytes(postdata));
        txtResponse.Text = Encoding.ASCII.GetString(responce);
    }

在哪里可以在Delphi中找到像WebClient这样的(好/可信赖)类?免费首选:)

编辑:
我希望VIEWSTATE,EVENTVALIDATION的机制对您足够清楚,它们是服务器生成的哈希值,并且它们可能会更改(已经更改),我的原始项目中有一段代码只是用于提取当前的VIEWSTATE,EVENTVALIDATION值,但是我省略该部分只是为了使我的示例简单明了,因此,当您尝试上面的代码时,必须从当前页面源中获取VIEWSTATE,EVENTVALIDATION值。

最佳答案

这很可能是由于以下事实造成的:在C#中,您使用&符号()字符来连接VIEWSTATE,EVENTVALIDATION和FORMPARAMS。

但是在Delphi中,您使用了TStringList和Add。
Add不会在与号之间添加(&)(),而是在两个之间添加CR + LF。

因此,您在Delphi中发送的数据与在C#中发送的数据不同。

如果您在Delphi中更改字符串连接逻辑以匹配C#中的逻辑,则无论您在Delphi端使用哪种WebClient,它都应该起作用。

--jeroen

编辑:20090830

此代码有效;使用Fiddler2检查C#和IE7输出,我发现您还需要转义'/'和'='字符。

编辑2:20090831

自昨天以来,网站上的VIEWSTATE和EVENTVALIDATION有所改变(尽管我不确定为什么)。我已经更改了代码,并且在将我的更改发布到此答案时有效。
这是从Internet Explorer 7中发布页面时每个Fiddler捕获的新请求内容:

__VIEWSTATE=%2FwEPDwUKMjA3NjE4MDczNmRk5%2FC2iWwvlAB3L1wYzRpm3KZhRC0%3D&__EVENTVALIDATION=%2FwEWAwLXzuATAuzRsusGAoznisYGSYOqDGy4vMunY6A8xi6ahQEPI5Q%3D&TextBox1=Issam&Button1=Button

这是从Delphi示例发布时的新请求:
__VIEWSTATE=%2FwEPDwUKMjA3NjE4MDczNmRk5%2FC2iWwvlAB3L1wYzRpm3KZhRC0%3D&__EVENTVALIDATION=%2FwEWAwLXzuATAuzRsusGAoznisYGSYOqDGy4vMunY6A8xi6ahQEPI5Q%3D&TextBox1=Issam&Button1=Button

现在,以下示例给出了此结果(请注意结果中的“ Issam ”):
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head><title>

</title></head>
<body>
    <form name="form1" method="post" action="page1.aspx" id="form1">
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUKMjA3NjE4MDczNg9kFgICAw9kFgICBQ8PFgIeBFRleHQFDVdlbGNvbWUgSXNzYW1kZGSCDMOkTMjkZJgqLkhpK99twpD5+A==" />

<input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" value="/wEWAwKr+O/BBQLs0bLrBgKM54rGBlueO5BU/6BAJMZfHNwh5fsQFuAm" />
    <div>

        <input name="TextBox1" type="text" value="Issam" id="TextBox1" />
        <input type="submit" name="Button1" value="Button" id="Button1" />

        <br />

        <span id="Label1">Welcome Issam</span>
        <br />

    </div>
    </form>
</body>
</html>

编辑3:20090831

确实,VIEWSTATE和EVENTVALIDATION再次发生了变化:它们以某种方式不断变化:似乎涉及时间因素。

所以我修改了代码,现在它可以从GET请求中提取VIEWSTATE和EVENTVALIDATION,然后将其放入POST请求中。

此外,似乎也需要转义“+”和“:”。
因此,我深入研究了ASP.NET页面生成逻辑,发现它们使用HttpUtility.UrlEncode进行转义,最终转义 HttpUtility。
因此,我将Reflector反向工程的Delphi代码改编为THttpUtility类。

这是最终的代码:
{$DEFINE FIDDLER}

unit HttpPostExampleFormUnit;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient, IdHTTP;

type
  THttpPostExampleForm = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    procedure Log(const What: string; const Content: string);
    procedure LogClear;
  end;

var
  HttpPostExampleForm: THttpPostExampleForm;

implementation

uses
  HttpUtilityUnit;

{$R *.dfm}

procedure AddFormParameter(const StringStream: TStringStream; const ParameterName: string; const ParameterValue: string);
var
  EncodedParameterValue: string;
begin
  StringStream.WriteString(ParameterName);
  StringStream.WriteString('=');
  EncodedParameterValue := THttpUtility.UrlEncode(ParameterValue);
  StringStream.WriteString(EncodedParameterValue);
end;

procedure AddFormParameterSeparator(const StringStream: TStringStream);
begin
  StringStream.WriteString('&');
end;

function ExtractHiddenParameter(const ParameterName: string; const Request: string): string;
//<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUKMjA3NjE4MDczNg9kFgICAw9kFgICBQ8PFgIeBFRleHQFDVdlbGNvbWUgSXNzYW1kZGSCDMOkTMjkZJgqLkhpK99twpD5+A==" />
const
  PrefixMask = 'input type="hidden" name="%s" id="%s" value="';
  Suffix = '" />';
var
  Prefix: string;
  PrefixLength: Integer;
  PrefixPosition: Integer;
  SuffixPosition: Integer;
begin
  Prefix := Format(PrefixMask, [ParameterName, ParameterName]);
  PrefixPosition := Pos(Prefix, Request);
  if PrefixPosition = 0 then
    Result := ''
  else
  begin
    PrefixLength := Length(Prefix);
    Result := Copy(Request,
      PrefixPosition + PrefixLength,
      1 + Length(Request) - PrefixPosition - PrefixLength);
    SuffixPosition := Pos(Suffix, Result);
    if SuffixPosition = 0 then
      Result := ''
    else
      Delete(Result, SuffixPosition, 1 + Length(Result) - SuffixPosition);
  end;
end;

procedure THttpPostExampleForm.Button1Click(Sender: TObject);
const
  DefaultVIEWSTATE = '/wEPDwUKMjA3NjE4MDczNmRk5%2FC2iWwvlAB3L1wYzRpm3KZhRC0=';
  DefaultEVENTVALIDATION = '/wEWAwLXzuATAuzRsusGAoznisYGSYOqDGy4vMunY6A8xi6ahQEPI5Q=';
  FORMPARAMS = 'TextBox1=Issam&Button1=Button';
  URL = 'http://issamsoft.com/app2/page1.aspx';
  __VIEWSATE = '__VIEWSTATE';
  __EVENTVALIDATION = '__EVENTVALIDATION';
var
  VIEWSTATE: string;
  EVENTVALIDATION: string;
  getHttp: TIdHttp;
  getRequest: string;
  postHttp: TIdHttp;
  ParametersStringStream: TStringStream;
  postRequest: string;
begin
  LogClear();
  getHttp := TIdHTTP.Create(self);
  try
    getRequest := getHttp.Get(URL);
    Log('GET Request', getRequest);
    VIEWSTATE := ExtractHiddenParameter(__VIEWSATE, getRequest);
    EVENTVALIDATION := ExtractHiddenParameter(__EVENTVALIDATION, getRequest);
    Log('Extracted VIEWSTATE', VIEWSTATE);
    Log('Extracted EVENTVALIDATION', EVENTVALIDATION);
  finally
    getHttp.Free();
  end;

  postHttp := TIdHTTP.Create(self);
{$IFDEF FIDDLER}
  postHttp.ProxyParams.ProxyServer := '127.0.0.1';
  postHttp.ProxyParams.ProxyPort := 8888;
{$ENDIF FIDDLER}
  postHttp.HTTPOptions := postHttp.HTTPOptions + [hoKeepOrigProtocol];
  ParametersStringStream := TStringStream.Create('');
  try
    AddFormParameter(ParametersStringStream, __VIEWSATE, VIEWSTATE);
    AddFormParameterSeparator(ParametersStringStream);
    AddFormParameter(ParametersStringStream, __EVENTVALIDATION, EVENTVALIDATION);
    AddFormParameterSeparator(ParametersStringStream);
    ParametersStringStream.WriteString(FORMPARAMS);
    postHttp.Request.ContentType := 'application/x-www-form-urlencoded';
    ParametersStringStream.Seek(0, soFromBeginning);
    Log('POST Parameters', ParametersStringStream.DataString);
    postRequest := postHttp.Post(url, ParametersStringStream);
    Log('POST Request', postRequest);
  finally
    postHttp.Free;
    ParametersStringStream.Free;
  end;
end;

procedure THttpPostExampleForm.Log(const What, Content: string);
begin
  Memo1.Lines.Add(What + '=');
  Memo1.Lines.Add(Content);
end;

procedure THttpPostExampleForm.LogClear;
begin
  Memo1.Lines.Clear;
end;

end.

和THttpUtlity类:
unit HttpUtilityUnit;

interface

type
  THttpUtility = class
  private
    class function IsSafe(const ch: Char): boolean;
  public
    class function UrlEncode(s: string): string;
  end;

implementation

uses
  Classes, SysUtils;

class function THttpUtility.IsSafe(const ch: Char): boolean;
begin
  if ((((ch >= 'a') and (ch <= 'z')) or ((ch >= 'A') and (ch <= 'Z'))) or ((ch >= '0') and (ch <= '9'))) then
    Result := True
  else
    case ch of
      '''',
        '(',
        ')',
        '*',
        '-',
        '.',
        '_',
        '!':
        Result := True;
    else
      Result := False;
    end;
end;

class function THttpUtility.UrlEncode(s: string): string;
var
  ch: Char;
  HexCh: string;
  StringStream: TStringStream;
  Index: Integer;
  Ordinal: Integer;
begin
  StringStream := TStringStream.Create('');
  try
    //Note: this is not yet UTF-16 compatible; check before porting to Delphi 2009
    for Index := 1 to Length(s) do
    begin
      ch := s[Index];
      if IsSafe(ch) then
        StringStream.WriteString(Ch)
      else
      begin
        Ordinal := Ord(Ch);
        HexCh := IntToHex(Ordinal, 2);
        StringStream.WriteString('%'+HexCh);
      end;
    end;

    Result := StringStream.DataString;
  finally
    StringStream.Free;
  end;
end;

end.

这应该可以帮助您。

--jeroen

关于asp.net - 使用Delphi和TIdHttp将数据发布到ASP .NET页面,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/1351181/

10-11 04:48
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