为什么我收到此代码的“NotSupportedException”？

Question

我正在尝试使用以下代码从手持设备（Compact Framework）调用 Web API 方法：

// "fullFilePath" is a value such as "\Program Files\Bla\abc.xml"
// "uri" is something like "http://localhost:28642/api/ControllerName/PostArgsAndXMLFile?serialNum=8675309&siteNum=42"
SendXMLFile(fullFilePath, uri, 500);
. . .
public static string SendXMLFile(string xmlFilepath, string uri, int timeout) 
{
    uri = uri.Replace('\\', '/');
    if (!uri.StartsWith("/"))
    {
        uri = "/" + uri;
    }
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

    request.KeepAlive = false;
    request.ProtocolVersion = HttpVersion.Version10;

    request.Method = "POST";

    StringBuilder sb = new StringBuilder();
    using (StreamReader sr = new StreamReader(xmlFilepath))
    {
        String line;
        while ((line = sr.ReadLine()) != null)
        {
            sb.AppendLine(line);
        }
        byte[] postBytes = Encoding.UTF8.GetBytes(sb.ToString());

        if (timeout < 0)
        {
            request.ReadWriteTimeout = timeout;
            request.Timeout = timeout;
        }

        request.ContentLength = postBytes.Length;
        request.KeepAlive = false;

        request.ContentType = "application/x-www-form-urlencoded"; // not "text/xml" correct?

        try
        {
            Stream requestStream = request.GetRequestStream();

            requestStream.Write(postBytes, 0, postBytes.Length);
            requestStream.Close();

            using (var response = (HttpWebResponse)request.GetResponse())
            {
                return response.ToString();
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
            request.Abort();
            return string.Empty;
        }
    }
}

在 SendXMLFile() 中的某处，它因“NotSupportedException”而失败...由于它在手持设备上运行，我无法在其中设置断点它并逐步通过它；我可以在整个 (MessageBox.Show()) 中添加一堆调试语句，但我宁愿不这样做。

服务器代码甚至没有到达我在下面的“XDocument doc =”行中设置的断点：

[Route("api/ControllerName/PostArgsAndXMLFile")]
public void PostArgsAndFile([FromBody] string stringifiedXML, string serialNum, string siteNum)
{
    XDocument doc = XDocument.Parse(stringifiedXML); 

是不是因为某种原因，Compact 框架不能调用（RESTful）Web API 方法？显然，客户端（手持式/紧凑型框架）编译并运行，它只是拒绝真正遵循所有的运行时现实。

我的代码是否需要稍作改动才能适应，还是我需要采取完全不同的策略？

Answer 1

Web API 将无法处理您的正文内容。您将其声明为 application/x-form-urlencoded，但它实际上是 XML 格式的，并且您的方法签名期望它是一个 XMLDataContract 序列化 string。

不要使用参数stringifiedXML，而是只需读取方法中的主体..

[Route("api/ControllerName/PostArgsAndXMLFile")]
public async void PostArgsAndFile(string serialNum, string siteNum)
{
    XDocument doc = XDocument.Parse(await Request.Content.ReadAsStringAsync()); 
}

或者事件更好，直接使用流。

[Route("api/ControllerName/PostArgsAndXMLFile")]
public async void PostArgsAndFile(string serialNum, string siteNum)
{
    XDocument doc = XDocument.Load(await Request.Content.ReadAsStreamAsync()); 
}

这样，您可以将客户端上的 ContentType 按原样放回application/xml。

Answer 2

在服务器端使用 Darrel 的代码（我使用的是第二个，Stream），这适用于客户端：

public static string SendXMLFile(string xmlFilepath, string uri, int timeout)
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

    request.KeepAlive = false;
    request.ProtocolVersion = HttpVersion.Version10;
    request.ContentType = "application/xml";
    request.Method = "POST";

    StringBuilder sb = new StringBuilder();
    using (StreamReader sr = new StreamReader(xmlFilepath))
    {
        String line;
        while ((line = sr.ReadLine()) != null)
        {
            sb.AppendLine(line);
        }
        byte[] postBytes = Encoding.UTF8.GetBytes(sb.ToString());

        if (timeout < 0)
        {
            request.ReadWriteTimeout = timeout;
            request.Timeout = timeout;
        }

        request.ContentLength = postBytes.Length;
        request.KeepAlive = false;

        request.ContentType = "application/x-www-form-urlencoded";

        try
        {
            Stream requestStream = request.GetRequestStream();

            requestStream.Write(postBytes, 0, postBytes.Length);
            requestStream.Close();

            using (var response = (HttpWebResponse)request.GetResponse())
            {
                return response.ToString();
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
            request.Abort();
            return string.Empty;
        }
    }
}

可以这样称呼：

private void buttonNose_Click(object sender, EventArgs e)
{
    String fullFilePath = @"C:\McMurtry\LonesomeDove.XML";
    String uri = @"http://localhost:21608/api/inventory/sendxml/ff/gg/42";
    SendXMLFile(fullFilePath, uri, 500);
}