.NET5使用WCF调用SOAP服务如何仅修改响应支持的Content-Type

针对你遇到的WCF客户端请求/响应要求不同Content-Type的问题，最优方案是实现仅修改响应Content-Type识别逻辑的自定义消息编码器，完全不需要改动请求发送逻辑，也不用更换框架重写代码。

实现步骤 #

1. 自定义消息编码器 #

该编码器会在写入请求时保留默认的text/xml类型，仅在读取响应时兼容application/xml类型：

// 自定义消息编码器
public class CustomTextMessageEncoder : MessageEncoder
{
    private readonly MessageEncoder _defaultEncoder;

    public CustomTextMessageEncoder(MessageEncoder defaultEncoder)
    {
        _defaultEncoder = defaultEncoder;
    }

    // 请求发出时固定用text/xml，符合服务端要求
    public override string ContentType => "text/xml";
    public override string MediaType => "text/xml";
    public override MessageVersion MessageVersion => _defaultEncoder.MessageVersion;

    // 处理响应时自动兼容application/xml
    public override Message ReadMessage(ArraySegment<byte> buffer, BufferManager bufferManager, string contentType)
    {
        if (contentType.Equals("application/xml", StringComparison.OrdinalIgnoreCase))
            contentType = "text/xml";
        return _defaultEncoder.ReadMessage(buffer, bufferManager, contentType);
    }

    public override Message ReadMessage(Stream stream, int maxSizeOfHeaders, string contentType)
    {
        if (contentType.Equals("application/xml", StringComparison.OrdinalIgnoreCase))
            contentType = "text/xml";
        return _defaultEncoder.ReadMessage(stream, maxSizeOfHeaders, contentType);
    }

    // 写入请求完全复用默认逻辑，保证Content-Type符合要求
    public override ArraySegment<byte> WriteMessage(Message message, int maxMessageSize, BufferManager bufferManager, int messageOffset)
    {
        return _defaultEncoder.WriteMessage(message, maxMessageSize, bufferManager, messageOffset);
    }

    public override void WriteMessage(Message message, Stream stream)
    {
        _defaultEncoder.WriteMessage(message, stream);
    }
}

// 编码器工厂
public class CustomTextMessageEncoderFactory : MessageEncoderFactory
{
    private readonly CustomTextMessageEncoder _encoder;
    public CustomTextMessageEncoderFactory(MessageEncoderFactory defaultFactory)
    {
        _encoder = new CustomTextMessageEncoder(defaultFactory.Encoder);
    }
    public override MessageEncoder Encoder => _encoder;
    public override MessageVersion MessageVersion => _encoder.MessageVersion;
}

// 自定义绑定元素，用于替换默认编码逻辑
public class CustomTextMessageBindingElement : MessageEncodingBindingElement
{
    private readonly TextMessageEncodingBindingElement _defaultEncodingElement;
    public CustomTextMessageBindingElement(TextMessageEncodingBindingElement defaultElement)
    {
        _defaultEncodingElement = defaultElement;
    }
    public override MessageEncoderFactory CreateMessageEncoderFactory()
    {
        return new CustomTextMessageEncoderFactory(_defaultEncodingElement.CreateMessageEncoderFactory());
    }
    public override MessageVersion MessageVersion
    {
        get => _defaultEncodingElement.MessageVersion;
        set => _defaultEncodingElement.MessageVersion = value;
    }
    public override BindingElement Clone()
    {
        return new CustomTextMessageBindingElement((TextMessageEncodingBindingElement)_defaultEncodingElement.Clone());
    }
}

2. 替换原有绑定配置 #

不需要修改你原有业务调用逻辑，仅需要把默认的BasicHttpBinding替换为添加了自定义编码元素的自定义绑定即可：

// 复用原有BasicHttpBinding的所有配置，仅替换编码逻辑
var defaultBinding = new BasicHttpBinding();
var customBinding = new CustomBinding(defaultBinding);

// 替换默认的文本编码元素
var defaultEncodingElement = customBinding.Elements.Find<TextMessageEncodingBindingElement>();
customBinding.Elements.Remove(defaultEncodingElement);
customBinding.Elements.Insert(0, new CustomTextMessageBindingElement(defaultEncodingElement));

// 后续调用逻辑和你原来的代码完全一致
var endpoint = new EndpointAddress("http://[...]/inquiry");
var channelFactory = new ChannelFactory<InquiryServiceSoapPort>(customBinding, endpoint);
var serviceClient = channelFactory.CreateChannel();
var inquiry = new Inquiry();
var result = serviceClient.createInquiry(inquiry);

方案说明 #

• 完全是客户端侧修改，不需要服务端做任何调整
• 请求发出的Content-Type仍然是服务端要求的text/xml，不会被服务端拒绝
• 仅在响应处理阶段将application/xml转换为WCF默认支持的text/xml，不影响任何业务逻辑解析
• 不需要重写整个调用逻辑，仅需要调整绑定配置即可

内容的提问来源于stack exchange，提问作者thorstenmz