http://www.bankofcanada.ca/stats/assets/rates_RSS/noon/en_all.xml

我正在使用以下相当简单的代码：

var
   szUrl: string;
   http: IXMLHTTPRequest;
begin
   szUrl := 'http://www.bankofcanada.ca/stats/assets/rates_RSS/noon/en_all.xml';

   http := CoXMLHTTP60.Create;
   http.open('GET',szUrl,False,'','');
   http.send(EmptyParam);

   Assert(http.Status = 200);

   Memo1.Lines.Add('HTTP/1.1 '+IntToStr(http.status)+' '+http.statusText);
   Memo1.Lines.Add(http.getAllResponseHeaders);
   Memo1.Lines.Add(http.responseText);

我不会显示返回的所有正文,但它会在responseText中返回有效的xml：

HTTP/1.1 200 OK
Cache-Control: max-age=5
Connection: keep-alive
Connection: Transfer-Encoding
Date: Fri,30 Mar 2012 14:50:50 GMT
Transfer-Encoding: chunked
Content-Type: text/html; charset=UTF-8
Expires: Fri,30 Mar 2012 14:50:55 GMT
Server: Apache/2.2.16 (Unix) PHP/5.3.3 mod_ssl/2.2.16 OpenSSL/1.0.0d mod_perl/2.0.4 Perl/v5.12.0
X-Powered-By: PHP/5.3.3


<?xml version="1.0" encoding="ISO-8859-1"?>
<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-Syntax-ns#"
    xmlns="http://purl.org/RSS/1.0/"
    xmlns:cb="http://www.cbwiki.net/wiki/index.PHP/Specification_1.1"
    xmlns:dc="http://purl.org/dc/elements/1.1/"
    xmlns:dcterms="http://purl.org/dc/terms/"
    xmlns:xsi="http://www.w3c.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.w3c.org/1999/02/22-rdf-Syntax-ns#rdf.xsd">
    <channel rdf:about="http://www.bankofcanada.ca/stats/assets/rates_RSS/noon/en_ALL.xml">
        <title xml:lang="en">Bank of Canada: Noon Foreign Exchange Rates</title>
        <link>http://www.bankofcanada.ca/rates/exchange/noon-rates-5-day/</link>

好的,很好,那里有有效的xml.我知道这是有效的,因为……好好看看它.但我也知道通过解析它是有效的：

var
   ...
   szXml: WideString;
   doc: DOMDocument60;
begin
   ...
   szXml := http.responseText;

   doc.loadXML(szXml);
   Assert(doc.parseError.errorCode = 0);

   Memo1.Lines.Add('============parsed xml');
   Memo1.Lines.Add(doc.xml);

原始IXmlHttpRequest包含responseXml财产.来自MSDN：

Represents the parsed response entity body.

If the response entity body is not valid XML,this property returns DOMDocument that was parsed so that you can access the error. This property does not return IXMLDOMParseError itself,but it is accessible from DOMDocument.

在我的情况下,responseXml属性存在,因为它应该：

Assert(http.responseXml <> nil);

并且没有responseText的解析错误：

doc := http.responseXml as DOMDocument60;
Assert(doc.parseError.errorCode = 0);

应该有,因为xml是有效的.

除了当我查看http.responseXml文档对象时,它是空的：

Memo1.Lines.Add('============responseXml');
   Memo1.Lines.Add(doc.xml);

是时IXMLHttpRequest(和IXMLServerHttpRequest)返回一个空的XML文档,时间为：

>有xml
> xml有效
>没有解析错误

长形式：

uses
    msxml2_tlb;

procedure TForm1.Button1Click(Sender: TObject);
var
    szUrl: string;
    http: IXMLHTTPRequest;
    doc: DOMDocument60;
begin
    szUrl := 'http://www.bankofcanada.ca/stats/assets/rates_RSS/noon/en_all.xml';

    http := CoXMLHTTP60.Create; //or CoServerXmlHttpRequest.Create
    http.open('GET','');
    http.send(EmptyParam);

    Assert(http.Status = 200);

    doc := http.responseXml as DOMDocument60;
    Assert(doc.parseError.errorCode = 0);

    ShowMessage('"'+doc.xml+'"');
end;

我如何使XmlHttpRequest(更重要的是ServerXMLHTTP60)表现得像记录的那样？