身體參數'寬度'。 GET操作不能有正文？

Question

我試着從一個WCF休息服務中獲得的圖像，像這樣：

[ServiceContract] 
public interface IReceiveData 
{ 
    [OperationContract] 
    [WebInvoke(Method = "GET", BodyStyle = WebMessageBodyStyle.Bare, ResponseFormat = WebMessageFormat.Xml, UriTemplate = "picture/")] 
    //this line is wrong though 
    Stream GetImage(int width, int height); 
} 
public class RawDataService : IReceiveData 
{ 
    public Stream GetImage(int width, int height) 
    { 
     // Although this method returns a jpeg, it can be 
     // modified to return any data you want within the stream 
     Bitmap bitmap = new Bitmap(width, height); 
     for (int i = 0; i < bitmap.Width; i++) 
     { 
      for (int j = 0; j < bitmap.Height; j++) 
      { 
       bitmap.SetPixel(i, j, (Math.Abs(i - j) < 2) ? Color.Blue : Color.Yellow); 
      } 
     } 
     MemoryStream ms = new MemoryStream(); 
     bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); 
     ms.Position = 0; 
     WebOperationContext.Current.OutgoingResponse.ContentType = "image/jpeg"; 
     return ms; 
    } 
} 

在我的主機應用程序：

class Program 
    { 
     static void Main(string[] args) 
     { 
      string baseAddress = "http://" + Environment.MachineName + ":8000/Service"; 
      ServiceHost host = new ServiceHost(typeof(RawDataService), new Uri(baseAddress)); 
      host.AddServiceEndpoint(typeof(IReceiveData), new WebHttpBinding(), "").Behaviors.Add(new WebHttpBehavior()); 
      host.Open(); // this line 
      Console.WriteLine("Host opened"); 
      Console.ReadLine(); 

我得到這個錯誤：

Operation 'GetImage' in contract 'IReceiveData' uses GET, but also has body parameter 'width'. GET operations cannot have a body. Either make the parameter 'width' a UriTemplate parameter, or switch from WebGetAttribute to WebInvokeAttribute.

林不知道如何爲圖像設置webinvoke/UriTemplate方法，或者如何獲取圖像並將其返回。在這個例子中，有人可以發佈正確的方式來顯示圖像。

編輯

如果我嘗試下面的答案，並用UriTemplate = "picture?w={width}&h={height}"作爲我UriTemplate導航到http://www.localhost.com:8000/Service/picture?width=50&height=40當我收到一個錯誤在我的代碼：

public Stream GetImage(int width, int height) 
     { 
      Bitmap bitmap = new Bitmap(width, height); // this line 
      for (int i = 0; i < bitmap.Width; i++) 
      { 
       for (int j = 0; j < bitmap.Height; j++) 
       { 
        bitmap.SetPixel(i, j, (Math.Abs(i - j) < 2) ? Color.Blue : Color.Yellow); 
       } 
      } 
      MemoryStream ms = new MemoryStream(); 
      bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); 
      ms.Position = 0; 
      WebOperationContext.Current.OutgoingResponse.ContentType = "image/jpeg"; 
      return ms; 
     } 

其中規定ArguementException was unhandled by user code:參數無效。

Answer 1

在這些屬性中，您需要告訴運行時您將期待寬度和高度作爲URL參數。

目前，運行時假定您調用URL時沒有參數，但被調用的方法需要參數，所以運行時真的不知道如何找到要傳遞給您的方法的值width和height。

這可以像

[WebInvoke(Method = "GET", BodyStyle = WebMessageBodyStyle.Bare, ResponseFormat = WebMessageFormat.Xml, UriTemplate = "picture/{width}/{height}")] 
Stream GetImage(string width, string height) 
{ 
    int w, h; 
    if (!Int32.TryParse(width, out w)) 
    { 
     // Handle error: use default values 
     w = 640; 
    } 
    if (!Int32.TryParse(height, out h)) 
    { 
     // Handle error use default values 
     h = 480; 
    } 

    .... 
} 

，你將需要調用URL像http://test.tld/picture/320/200。

Answer 2

UriTemplate = "picture/" 

應該像

UriTemplate = "picture?w={width}&h={height}" 

這告訴WCF如何從URL中的寬度和高度參數。