asp.net webapi 序列化为xml 时实体属性增加<![CDATA[]]>防止特殊字符

有时webapi在序列化xml时，可能需要给某些带有html或特殊字符（如 < > & /）的字段加上<![CDATA[]]> 已防止影响xml正常数据，如果使用.aspx视图那可直接在前台绑定字段时直接加入<![CDATA[]]>，webapi只有后台代码，那只能在后台做了，如下。

 using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Net;
 using System.Net.Http;
 using System.Net.Http.Formatting;
 using System.Threading.Tasks;
 using System.Web.Http;
 using System.Xml;
 using System.Xml.Serialization;

 namespace MvcApplication1.Controllers
 {
     public class TestController : ApiController
     {
         [HttpGet]
         [HttpPost]
         public HttpResponseMessage HouseTest(string city)
         {
             //手动构造数据，这里应该是调用构造数据。
             var info = new GetHouseCountInfo()
             {
                 CityName = "北京",
                 CountInfo = new List<CountInfo>()
                 {
                     new CountInfo()
                     {
                         Data = "2016-08-30",
                         HouseDetail = "描述信息1111等。。。"
                     },
                     new CountInfo()
                     {
                         Data = "2016-08-30",
                         HouseDetail = "描述信息2222等。。。"
                     },
                     new CountInfo()
                     {
                         Data = "2016-08-30",
                         HouseDetail = "描述信息333等。。。"
                     }
                 }
             };
             //序列化实体与赋值
             var model = new HouseCountRoot {GetHouseInfo = new GetHouseCountInfo()};
             model.GetHouseInfo.CountInfo = info.CountInfo;
             model.Result = "";
             model.Message = "";
             model.GetHouseInfo.CityName = info.CityName;

             return new HttpResponseMessage()
             {
                 Content =
                     new ObjectContent<HouseCountRoot>(model, new CustomNamespaceXmlFormatter() {UseXmlSerializer = true},
                         new System.Net.Http.Headers.MediaTypeHeaderValue("application/xml") {CharSet = "utf-8"}),
                 StatusCode = HttpStatusCode.OK
             };
         }
     }

     [XmlRoot("houses")]
     public class HouseCountRoot
     {
         [XmlElement("result")]
         public string Result { get; set; }

         [XmlElement("message")]
         public string Message { get; set; }

         [XmlElement("housecount")]
         public GetHouseCountInfo GetHouseInfo { get; set; }
     }

     public class GetHouseCountInfo
     {
         /// <summary>
         /// 城市名称
         /// </summary>
         [XmlElement("cityname")]
         public string CityName { get; set; }

         /// <summary>
         /// 房源数信息
         /// </summary>
         [XmlElement("countinfo")]
         public List<CountInfo> CountInfo { get; set; }
     }

     public class CountInfo
     {
         /// <summary>
         /// 日期
         /// </summary>
         [XmlElement("data")]
         public string Data { get; set; }

         /// <summary>
         /// 加<![CDATA[ ]]>数据字段
         /// </summary>
         [XmlIgnore] //方式1，这里属性设置忽略，把CDataContent设置为housedetail
         public string HouseDetail { get; set; }

         [XmlElement("housedetail")]
         public XmlNode[] CDataContent
         {
             get
             {
                 return new XmlNode[]
                 {
                     new XmlDocument().CreateCDataSection(HouseDetail)
                 };
             }
             set
             {
                 HouseDetail =
                     value[].Value;
             }
         }

         //方式二，这里把CDataContent设置为housedetail
         //[XmlElement("housedetail")]
         //public XmlNode CDataContent
         //{
         //    get
         //    {
         //        // 这种方式这里代码比上面的要多运行一定次数。
         //        XmlNode node = new XmlDocument().CreateNode(XmlNodeType.CDATA, "", "");
         //        node.InnerText = HouseDetail;
         //        return node;
         //    }
         //    set
         //    {
         //        HouseDetail
         //            = value.Value;
         //    } //省略则CDataContent不会被序列化
         //}

         //以下属性省略。。。。
     }

     /// <summary>
     /// 去除xml命名空间的 序列化类
     /// </summary>
     public class CustomNamespaceXmlFormatter : XmlMediaTypeFormatter
     {
         public override Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content,
             TransportContext transportContext)
         {
             var xns = new XmlSerializerNamespaces();
             foreach (var attribute in type.GetCustomAttributes(true))
             {
                 var xmlRootAttribute = attribute as XmlRootAttribute;
                 if (xmlRootAttribute != null)
                 {
                     xns.Add(string.Empty, xmlRootAttribute.Namespace);
                 }
             }

             if (xns.Count == )
             {
                 xns.Add(string.Empty, string.Empty);
             }

             var task = Task.Factory.StartNew(() =>
             {
                 var serializer = new XmlSerializer(type);
                 serializer.Serialize(writeStream, value, xns);
             });

             return task;
         }
     }
 }

结果如下。

 <?xml version="1.0"?>
 <houses>
   <result />
   <message />
   <housecount>
     <cityname>北京</cityname>
     <countinfo>
       <data>2016-08-30</data>
       <housedetail><![CDATA[描述信息1111等。。。]]></housedetail>
     </countinfo>
     <countinfo>
       <data>2016-08-30</data>
       <housedetail><![CDATA[描述信息2222等。。。]]></housedetail>
     </countinfo>
     <countinfo>
       <data>2016-08-30</data>
       <housedetail><![CDATA[描述信息333等。。。]]></housedetail>
     </countinfo>
   </housecount>
 </houses>