如何强制WCF Rest客户端使用Json反序列化器而不考虑内容类型?
我正在通过WCF调用基于REST的Web服务。
服务返回JSON主体,但内容类型为“Application / xml”。 WCF框架现在给我XmlException。
public class MessageFormatter : IClientMessageFormatter
{
private readonly IClientMessageFormatter _formatter;
public MessageFormatter(IClientMessageFormatter formatter)
{
_formatter = formatter;
}
public object DeserializeReply(System.ServiceModel.Channels.Message message, object[] parameters)
{
return _formatter.DeserializeReply(message, parameters);
}
}
_formatter.DeserializeReply抛出XmlException。我无法在任何地方找到任何强制json反序列化的例子。
编辑 - 鼠标悬停时的“消息”对象正在抛出“{...错误读取正文:System.Xml.XmlException:根级别的数据无效。第1行,位置1. ...}”
我的另一个项目中与另一个REST服务(Picasa Web服务)通信的同一个对象有一个看起来像是JSON对象的xml序列化版本?所以这个问题似乎在流程中更进一步。我需要找到这个对象的起源。我将继续使用MessageEncoder类。
编辑 - (添加更多信息)
public class MyBinding : WebHttpBinding
{
public MyBinding(WebHttpSecurityMode mode)
: base(mode)
{
}
public override BindingElementCollection CreateBindingElements()
{
var result = base.CreateBindingElements();
var replacements = result.OfType<MessageEncodingBindingElement>().ToList();
foreach (var messageEncodingBindingElement in replacements)
{
var index = result.IndexOf(messageEncodingBindingElement);
result.Remove(messageEncodingBindingElement);
result.Insert(index, new MyMessageEncodingBindingElement(messageEncodingBindingElement));
}
return result;
}
}
public class MyMessageEncodingBindingElement : MessageEncodingBindingElement
{
private readonly MessageEncodingBindingElement _element;
public MyMessageEncodingBindingElement(MessageEncodingBindingElement element)
{
_element = element;
}
public override BindingElement Clone()
{
var result = _element.Clone();
if (result is MessageEncodingBindingElement)
return new MyMessageEncodingBindingElement(result as MessageEncodingBindingElement);
return result;
}
public override MessageEncoderFactory CreateMessageEncoderFactory()
{
return new MyMessageEncoderFactory(_element.CreateMessageEncoderFactory());
}
}
即使在设置断点时命中构造函数和Clone方法,也永远不会调用CreateMessageEncoderFactory()方法。有帮助吗?我正在尝试设置自定义MessageEncoder和MessageEncoderFactory类来修改Message对象的实例化过程。
答案 0 :(得分:2)
您可以使用WebContentTypeMapper
。这是WebHttpBinding
的属性,您可以自定义编码器从该绑定执行反序列化的方式,包括强制它始终使用JSON反序列化器,而不管传入消息的Content-Type。下面的代码显示了如何做到这一点。
public class StackOverflow_13225272
{
[DataContract]
public class Person
{
[DataMember]
public string Name { get; set; }
[DataMember]
public int Age { get; set; }
public override string ToString()
{
return string.Format("Person[Name={0},Age={1}]", Name, Age);
}
}
[ServiceContract]
public interface ITest
{
[WebGet(ResponseFormat = WebMessageFormat.Json)]
Person GetPerson(string responseContentType);
}
public class Service : ITest
{
public Person GetPerson(string responseContentType)
{
WebOperationContext.Current.OutgoingResponse.ContentType = responseContentType;
return new Person { Name = "John Doe", Age = 29 };
}
}
class AllJsonContentTypeMapper : WebContentTypeMapper
{
public override WebContentFormat GetMessageFormatForContentType(string contentType)
{
return WebContentFormat.Json;
}
}
public static void Test()
{
string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
WebServiceHost host = new WebServiceHost(typeof(Service), new Uri(baseAddress));
host.Open();
Console.WriteLine("Host opened");
#if USE_NETFX4
// This works on .NET 4.0 and beyond
WebHttpBinding binding = new WebHttpBinding();
binding.ContentTypeMapper = new AllJsonContentTypeMapper();
#else
// This works on .NET 3.5
CustomBinding binding = new CustomBinding(new WebHttpBinding());
binding.Elements.Find<WebMessageEncodingBindingElement>().ContentTypeMapper = new AllJsonContentTypeMapper();
ChannelFactory<ITest> factory = new ChannelFactory<ITest>(binding, new EndpointAddress(baseAddress));
#endif
ChannelFactory<ITest> factory = new ChannelFactory<ITest>(binding, new EndpointAddress(baseAddress));
factory.Endpoint.Behaviors.Add(new WebHttpBehavior());
ITest proxy = factory.CreateChannel();
Console.WriteLine("With JSON: {0}", proxy.GetPerson("application/json"));
Console.WriteLine("With XML: {0}", proxy.GetPerson("application/xml"));
Console.Write("Press ENTER to close the host");
Console.ReadLine();
host.Close();
}
}
答案 1 :(得分:1)
这可能有用。
public class ForceJsonClientMessageFormatter : IClientMessageFormatter
{
private readonly DataContractJsonSerializer _jsonSerializer;
public ForceJsonClientMessageFormatter(Type responseType)
{
_jsonSerializer = new DataContractJsonSerializer(responseType);
}
public Message SerializeRequest(MessageVersion messageVersion, object[] parameters)
{
throw new NotImplementedException("This client message formatter is for replies only!");
}
public object DeserializeReply(Message message, object[] parameters)
{
string messageBody = message.GetBody<string>();
using (MemoryStream messageStream = new MemoryStream(Encoding.UTF8.GetBytes(messageBody)))
{
messageStream.Seek(0, SeekOrigin.Begin);
object deserializedObject = _jsonSerializer.ReadObject(messageStream);
return deserializedObject;
}
}
}
public class ForceJsonWebHttpBehavior : WebHttpBehavior
{
protected override IClientMessageFormatter GetReplyClientFormatter(OperationDescription operationDescription, ServiceEndpoint endpoint)
{
return new ForceJsonClientMessageFormatter(operationDescription.Messages[1].Body.ReturnValue.Type);
}
}
答案 2 :(得分:0)
我没试过,但我认为这会奏效。您可以创建一个自定义IClientMessageFormatter,将消息格式覆盖为Json,将其包装在行为中,然后将该行为应用于客户端端点配置。
public class ForceJsonClientMessageFormatterDecorator : IClientMessageFormatter
{
private readonly IClientMessageFormatter _decoratedFormatter;
public ForceJsonClientMessageFormatterDecorator(IClientMessageFormatter decoratedFormatter)
{
_decoratedFormatter = decoratedFormatter;
}
public object DeserializeReply(Message message, object[] parameters)
{
message.Properties[WebBodyFormatMessageProperty.Name] = new WebBodyFormatMessageProperty(WebContentFormat.Json);
return _decoratedFormatter.DeserializeReply(message, parameters);
}
public Message SerializeRequest(MessageVersion messageVersion, object[] parameters)
{
return _decoratedFormatter.SerializeRequest(messageVersion, parameters);
}
}
public class ForceJsonWebHttpBehavior : WebHttpBehavior
{
protected override IClientMessageFormatter GetReplyClientFormatter(OperationDescription operationDescription, ServiceEndpoint endpoint)
{
IClientMessageFormatter decoratedFormatter = base.GetReplyClientFormatter(operationDescription, endpoint);
return new ForceJsonClientMessageFormatterDecorator(decoratedFormatter);
}
}