如何在web api中使用c＃处理xml有效负载中的特殊字符

Question

我正在使用以下代码块来读取XML数据

 public async Task<IHttpActionResult> PostPurchaseOrder(HttpRequestMessage request)
    {          
        XmlDocument document = new XmlDocument();          
        document.Load(request.Content.ReadAsStreamAsync().Result);          
    }

但在XML数据中使用＆amp;，$，＃等特殊字符时面临问题

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE cXML SYSTEM "xml.cxml.org/schemas/cXML/1.2.008/cXML.dtd">; 
<cXML timestamp="2017-04-06T05:44:31-04:00" version="1.2.0025"
       payloadID="ddae78e3-20b0-4f9d-91b8-7ca854f27568" xml:lang="en-US"> 
 <Header> <From> <Credential domain="NetworkId"> 
  <Identity>FakeIdentity & &</Identity> 
  </Credential> </From> 
 </cXML>