javascript 从 RESTful WCF 服务返回图像
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Returning an image from a RESTful WCF service
提问by Amy
I have this very simple DTO:
我有这个非常简单的 DTO：
[DataContract]
public class DTO
{
[DataMember]
public byte[] Image {get; set; }
}
And this very simple service:
这个非常简单的服务：
[ServiceContract]
public interface IFooService
{
[WebGet(
UriTemplate = "",
RequestFormat = WebMessageFormat.Json,
ResponseFormat = WebMessageFormat.Json)]
List<DTO> GetDTOs();
}
In my global.asax, I have:
在我的 global.asax 中，我有：
RouteTable.Routes.Add(new ServiceRoute("foo",
new WebServiceHostFactory(), typeof(FooService)));
Now, when I call this from my browser, I am getting an array of bytes in JSON format. Good so far. Now, how do I turn that array of bytes into an image?
现在，当我从浏览器调用它时，我得到了一个 JSON 格式的字节数组。目前很好。现在，如何将该字节数组转换为图像？
Or, is there a better way of going about this? I tried changing byte[]to Stream, but then when I call the service from Firefox, the response is empty despite an HTTP status code of 200. I am using Firebug and Fiddler.
或者，有没有更好的方法来解决这个问题？我尝试更改byte[]为Stream，但是当我从 Firefox 调用该服务时，尽管 HTTP 状态代码为 200，但响应为空。我正在使用 Firebug 和 Fiddler。
I don't think it's relevant, but since too much information never hurt anybody who wasn't a robot, here's the web.config:
我认为这无关紧要，但由于过多的信息永远不会伤害非机器人的任何人，这里是 web.config：
<?xml version="1.0"?>
<configuration>
<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior>
<serviceMetadata httpGetEnabled="true"/>
<serviceDebug includeExceptionDetailInFaults="false"/>
</behavior>
</serviceBehaviors>
</behaviors>
<serviceHostingEnvironment multipleSiteBindingsEnabled="true" aspNetCompatibilityEnabled="true" />
</system.serviceModel>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true">
<add name="UrlRoutingModule" type="System.Web.Routing.UrlRoutingModule, System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
</modules>
</system.webServer>
<system.web>
<compilation debug="true" targetFramework="4.0" />
</system.web>
</configuration>
Ultimately, I guess the question is: how do you return a bitmap from a WCF RESTful service so JavaScript running in the browser can throw it up on the screen?
最后，我想问题是：如何从 WCF RESTful 服务返回位图，以便在浏览器中运行的 JavaScript 可以将其显示在屏幕上？
回答by Darin Dimitrov
Good so far. Now, how do I turn that array of bytes into an image?
目前很好。现在，如何将该字节数组转换为图像？
Since you have tagged your question with javascript I assume that this is what you use to consume the service and you want to display the image in the browser. If this is the case you may take a look at the Data URI schemewhich would allow you to show the image given the bytes you get from the service.
由于您已使用 javascript 标记了您的问题，因此我假设这是您用来使用服务的内容，并且您希望在浏览器中显示图像。如果是这种情况，您可以查看数据 URI 方案，它允许您根据从服务获得的字节显示图像。
Here's an example how you could consume such service using jQuery and show the image:
以下是如何使用 jQuery 使用此类服务并显示图像的示例：
$(function () {
$.getJSON('/foo/', function (dtos) {
$.each(dtos, function (index, dto) {
var str = String.fromCharCode.apply(String, dto.Image);
$('<img/>', {
alt: '',
src: 'data:image/png;base64,' + $.base64.encode(str)
}).appendTo('body');
});
});
});
The $.base64.encodefunction comes from this plugin.
该$.base64.encode功能来自这个插件。
回答by Slavo
The problem with using WCF to do this is that web service frameworks (and WCF in particular), make a lot of assumptions on the resulting response. When you request an image from a server, the HTTP response content type is usually different than that of an API request.
使用 WCF 执行此操作的问题在于 Web 服务框架（尤其是 WCF）对结果响应做出了很多假设。当您从服务器请求图像时，HTTP 响应内容类型通常与 API 请求不同。
This is why I don't think such a job should be implemented using WCF. I just answered a similar question asking the same, but with WebAPI rather than WCF:
这就是为什么我认为不应该使用 WCF 来实现这样的工作。我刚刚回答了一个类似的问题，但使用 WebAPI 而不是 WCF：
ASP .Net Web API downloading images as binary
You'd be much happier if you just implement a custom HTTP handler. APIs are for structured data, and images are not structured data - they are binary. They have their own place in HTTP and I think decoupling them from the API is a good idea.
如果您只是实现自定义HTTP 处理程序，您会更高兴。API 用于结构化数据，图像不是结构化数据——它们是二进制的。它们在 HTTP 中有自己的位置，我认为将它们与 API 分离是个好主意。
