如何在ASP.NET中返回XML？

类似的问题

如何在ASP.NET中返回XML

参考

如何从ASP.NET 1.1中的ASPX返回XML

将XML输出写入ASP.NET网页

如何从ASP.NET输出XML？

在ASP.NET中创建ASHX处理程序

我找到了在ASP.NET中将XML返回给客户端的正确方法.我想如果我指出错误的方法,它将使正确的方式更容易理解.

不正确:

Response.Write(doc.ToString());

不正确:

Response.Write(doc.InnerXml);

不正确:

Response.ContentType = "text/xml";
Response.ContentEncoding = System.Text.Encoding.UTF8;
doc.Save(Response.OutputStream);

正确:

Response.ContentType = "text/xml"; //Must be 'text/xml'
Response.ContentEncoding = System.Text.Encoding.UTF8; //We'd like UTF-8
doc.Save(Response.Output); //Save to the text-writer
      //using the encoding of the text-writer
      //(which comes from response.contentEncoding)

使用TextWriter

千万不能使用Response.OutputStream

不要使用Response.Output

两者都是流,但是Output是TextWriter.当XmlDocument将自身保存到TextWriter时,它将使用该TextWriter指定的编码.XmlDocument将自动更改xml声明节点以匹配TextWriter使用的编码.例如,在这种情况下,XML声明节点:

会成为

这是因为TextWriter已设置为UTF-8.(稍等一下).当TextWriter被输入字符数据时,它将使用适合其设置编码的字节序列对其进行编码.

不正确:

doc.Save(Response.OutputStream);

在此示例中,文档被错误地保存到OutputStream,后者不执行编码更改,并且可能与响应的内容编码或XML声明节点的指定编码不匹配.

正确

doc.Save(Response.Output);

XML文档正确保存到TextWriter对象,确保正确处理编码.

设置编码

标头中给客户端的编码:

Response.ContentEncoding = ...

必须匹配XML文档的编码:

必须匹配发送到客户端的字节序列中存在的实际编码.为了使所有这三件事达成一致,设置单行:

Response.ContentEncoding = System.Text.Encoding.UTF8;

在Response对象上设置编码时,它会在TextWriter上设置相同的编码.TextWriter的编码集导致XmlDocument更改xml声明:

文档保存时:

doc.Save(someTextWriter);

保存到响应输出

您不希望将文档保存为二进制流,也不想写入字符串:

不正确:

doc.Save(Response.OutputStream);

这里XML被错误地保存到二进制流中.最终字节编码序列与XML声明或Web服务器响应的内容编码不匹配.

不正确:

Response.Write(doc.ToString());
Response.Write(doc.InnerXml);

这里XML被错误地转换为字符串,该字符串没有编码.XML声明节点未更新以反映响应的编码,并且未正确编码响应以匹配响应的编码.此外,将XML存储在中间字符串中会浪费内存.

您不希望将XML保存到字符串中,或​​者将XML填充到字符串和response.Write字符串中,因为:

- doesn't follow the encoding specified
- doesn't set the XML declaration node to match
- wastes memory

不要使用doc.Save(Response.Output);

千万不能使用doc.Save(Response.OutputStream);

千万不能使用Response.Write(doc.ToString());

千万不能使用"的Response.Write(doc.InnerXml);`

设置内容类型

Response的ContentType必须设置为"text/xml".如果没有,客户端将不知道您正在发送XML.

最终答案

Response.Clear(); //Optional: if we've sent anything before
Response.ContentType = "text/xml"; //Must be 'text/xml'
Response.ContentEncoding = System.Text.Encoding.UTF8; //We'd like UTF-8
doc.Save(Response.Output); //Save to the text-writer
    //using the encoding of the text-writer
    //(which comes from response.contentEncoding)
Response.End(); //Optional: will end processing

Rob Kennedy有一个很好的观点,即我没有包括从头到尾的例子.

GetPatronInformation.ashx:

<%@ WebHandler Language="C#" Class="Handler" %>

using System;
using System.Web;
using System.Xml;
using System.IO;
using System.Data.Common;

//Why a "Handler" and not a full ASP.NET form?
//Because many people online critisized my original solution
//that involved the aspx (and cutting out all the HTML in the front file),
//noting the overhead of a full viewstate build-up/tear-down and processing,
//when it's not a web-form at all. (It's a pure processing.)

public class Handler : IHttpHandler
{
   public void ProcessRequest(HttpContext context)
   {
      //GetXmlToShow will look for parameters from the context
      XmlDocument doc = GetXmlToShow(context);

      //Don't forget to set a valid xml type.
      //If you leave the default "text/html", the browser will refuse to display it correctly
      context.Response.ContentType = "text/xml";

      //We'd like UTF-8.
      context.Response.ContentEncoding = System.Text.Encoding.UTF8;
      //context.Response.ContentEncoding = System.Text.Encoding.UnicodeEncoding; //But no reason you couldn't use UTF-16:
      //context.Response.ContentEncoding = System.Text.Encoding.UTF32; //Or UTF-32
      //context.Response.ContentEncoding = new System.Text.Encoding(500); //Or EBCDIC (500 is the code page for IBM EBCDIC International)
      //context.Response.ContentEncoding = System.Text.Encoding.ASCII; //Or ASCII
      //context.Response.ContentEncoding = new System.Text.Encoding(28591); //Or ISO8859-1
      //context.Response.ContentEncoding = new System.Text.Encoding(1252); //Or Windows-1252 (a version of ISO8859-1, but with 18 useful characters where they were empty spaces)

      //Tell the client don't cache it (it's too volatile)
      //Commenting out NoCache allows the browser to cache the results (so they can view the XML source)
      //But leaves the possiblity that the browser might not request a fresh copy
      //context.Response.Cache.SetCacheability(HttpCacheability.NoCache);

      //And now we tell the browser that it expires immediately, and the cached copy you have should be refreshed
      context.Response.Expires = -1;

      context.Response.Cache.SetAllowResponseInBrowserHistory(true); //"works around an Internet Explorer bug"

      doc.Save(context.Response.Output); //doc saves itself to the textwriter, using the encoding of the text-writer (which comes from response.contentEncoding)

      #region Notes
      /*
       * 1. Use Response.Output, and NOT Response.OutputStream.
       *  Both are streams, but Output is a TextWriter.
       *  When an XmlDocument saves itself to a TextWriter, it will use the encoding
       *  specified by the TextWriter. The XmlDocument will automatically change any
       *  XML declaration node, i.e.:
       *     
       *  to match the encoding used by the Response.Output's encoding setting
       * 2. The Response.Output TextWriter's encoding settings comes from the
       *  Response.ContentEncoding value.
       * 3. Use doc.Save, not Response.Write(doc.ToString()) or Response.Write(doc.InnerXml)
       * 3. You DON'T want to save the XML to a string, or stuff the XML into a string
       *  and response.Write that, because that
       *   - doesn't follow the encoding specified
       *   - wastes memory
       *
       * To sum up: by Saving to a TextWriter: the XML Declaration node, the XML contents,
       * and the HTML Response content-encoding will all match.
       */
      #endregion Notes
   }

   private XmlDocument GetXmlToShow(HttpContext context)
   {
      //Use context.Request to get the account number they want to return
      //GET /GetPatronInformation.ashx?accountNumber=619

      //Or since this is sample code, pull XML out of your rear:
      XmlDocument doc = new XmlDocument();
      doc.LoadXml("Rob Kennedy");

      return doc;
   }

   public bool IsReusable { get { return false; } }
}

理想情况下,您会使用ashx发送XML,尽管我允许ASPX中的代码拦截正常执行.

Response.Clear()

我不使用这个,如果你不确定你已经在响应中丢弃任何东西,那么就去找它并摆脱它.

Response.ContentType = "text/xml"

当然,如果不存在此内容类型,公共客户端将不会将内容接受为XML.

 Response.Charset = "UTF-8";

让响应类处理正确构建内容类型标头.使用UTF-8,除非你有一个非常,非常好的理由不这样做.

Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetAllowResponseInBrowserHistory(true);

如果您不发送缓存标头,某些浏览器(即IE)将缓存响应,后续请求不一定会到达服务器.如果您希望它通过HTTPS工作,您还需要AllowResponseInBrowser(由于IE中的另一个错误).

要发送XmlDocument的内容,只需使用:

dom.Save(Response.OutputStream);

dom.Save(Response.Output);

只要确保编码匹配,(使用UTF-8的另一个好理由).

该XmlDocument对象将自动将其嵌入encoding="..."编码调整为Response(例如UTF-8)

Response.End()

如果你真的需要在ASPX中,但它有点激烈,在ASHX中不要这样做.