CefSharp自定义SchemeHandler

我使用 CefSharp 的 SchemeHandler 来从我的 C# 项目中获取资源，例如.css, .js or .png例如使用自定义 url 的文件custom://cefsharp/assets/css/style.css

我有 2 个自定义类来存档这个。

头等舱，MyCustomSchemeHandlerFactory将是处理自定义方案的方案，它看起来像这样，其中“自定义”将是自定义方案：

internal class MyCustomSchemeHandlerFactory : ISchemeHandlerFactory
{
    public const string SchemeName = "custom";

    public IResourceHandler Create(IBrowser browser, IFrame frame, string schemeName, IRequest request)
    {
        return new MyCustomSchemeHandler();
    }
}

我实施的下一个课程是MyCustomSchemeHandler它将接收调用并输出响应，如下所示：

internal class MyCustomSchemeHandler : IResourceHandler
{

    private static readonly IDictionary<string, string> ResourceDictionary;

    private string mimeType;
    private MemoryStream stream;

    static MyCustomSchemeHandler()
    {
        ResourceDictionary = new Dictionary<string, string>
        {
            { "/home.html", Properties.Resources.index},
            { "/assets/css/style.css", Properties.Resources.style}
        };
    }

    public Stream Stream { get; set; }
    public int StatusCode { get; set; }
    public string StatusText { get; set; }
    public string MimeType { get; set; }
    public NameValueCollection Headers { get; private set; }

    public Stream GetResponse(IResponse response, out long responseLength, out string redirectUrl)
    {
        redirectUrl = null;
        responseLength = -1;

        response.MimeType = MimeType;
        response.StatusCode = StatusCode;
        response.StatusText = StatusText;
        response.ResponseHeaders = Headers;

        var memoryStream = Stream as MemoryStream;
        if (memoryStream != null)
        {
            responseLength = memoryStream.Length;
        }

        return Stream;
    }

    public bool ProcessRequestAsync(IRequest request, ICallback callback)
    {
        // The 'host' portion is entirely ignored by this scheme handler.
        var uri = new Uri(request.Url);
        var fileName = uri.AbsolutePath;
        string resource;

        if (ResourceDictionary.TryGetValue(fileName, out resource) && !string.IsNullOrEmpty(resource))
        {
            var resourceHandler = ResourceHandler.FromString(resource);
            stream = (MemoryStream)resourceHandler.Stream;

            var fileExtension = Path.GetExtension(fileName);
            mimeType = ResourceHandler.GetMimeType(fileExtension);

            callback.Continue();
            return true;
        }
        else
        {
            callback.Dispose();
        }

        return false;
    }

    void GetResponseHeaders(IResponse response, out long responseLength, out string redirectUrl)
    {
        responseLength = stream == null ? 0 : stream.Length;
        redirectUrl = null;

        response.StatusCode = (int)HttpStatusCode.OK;
        response.StatusText = "OK";
        response.MimeType = mimeType;
    }

    bool ReadResponse(Stream dataOut, out int bytesRead, ICallback callback)
    {
        //Dispose the callback as it's an unmanaged resource, we don't need it in this case
        callback.Dispose();

        if (stream == null)
        {
            bytesRead = 0;
            return false;
        }

        //Data out represents an underlying buffer (typically 32kb in size).
        var buffer = new byte[dataOut.Length];
        bytesRead = stream.Read(buffer, 0, buffer.Length);

        dataOut.Write(buffer, 0, buffer.Length);

        return bytesRead > 0;
    }

    bool CanGetCookie(Cookie cookie)
    {
        return true;
    }

    bool CanSetCookie(Cookie cookie)
    {
        return true;
    }

    void Cancel()
    {

    }

}

在此类中，我定义了一个自定义资源字典，它将指示将使用资源中的哪些文件，因此正如我在第一个示例中所述，custom://cefsharp/assets/css/style.css应该加载资源Properties.Resources.style，问题是，一旦我输入特定的网址，就不会加载任何内容，我尝试输出 mimeType 并且它可以工作，但不知何故文件本身无法正确输出。我的实现有问题吗？

另外，我尝试以以下形式输出原始文件：

if (ResourceDictionary.TryGetValue(fileName, out resource) && !string.IsNullOrEmpty(resource))
{
    MessageBox.Show(resource);
}

并且它输出正确的文件，没有任何问题。

要加载自定义方案，我在初始化 CefSharp 之前使用以下代码：

var settings = new CefSettings();
settings.RegisterScheme(new CefCustomScheme
{
    SchemeName = MyCustomSchemeHandlerFactory.SchemeName,
    SchemeHandlerFactory = new MyCustomSchemeHandlerFactory()
});

上述课程基于以下链接： 我的自定义方案处理工厂：FlashResourceHandlerFactory.cs我的自定义方案处理程序：CefSharpSchemeHandler.cs and 资源处理程序.cs

由于 Cefsharp 在过去几个月中发生了一些变化，这里提供了一种处理“文件”协议的更新且更简单的方法。我写博客文章在这个问题上。

您要添加的是您的方案处理程序及其工厂：

using System;
using System.IO;
using CefSharp;

namespace MyProject.CustomProtocol
{
    public class CustomProtocolSchemeHandler : ResourceHandler
    {
        // Specifies where you bundled app resides.
        // Basically path to your index.html
        private string frontendFolderPath;

        public CustomProtocolSchemeHandler()
        {
            frontendFolderPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "./bundle/");
        }

        // Process request and craft response.
        public override bool ProcessRequestAsync(IRequest request, ICallback callback)
        {
            var uri = new Uri(request.Url);
            var fileName = uri.AbsolutePath;

            var requestedFilePath = frontendFolderPath + fileName;

            if (File.Exists(requestedFilePath))
            {
                byte[] bytes = File.ReadAllBytes(requestedFilePath);
                Stream = new MemoryStream(bytes);

                var fileExtension = Path.GetExtension(fileName);
                MimeType = GetMimeType(fileExtension);

                callback.Continue();
                return true;
            }

            callback.Dispose();
            return false;
        }
    }

    public class CustomProtocolSchemeHandlerFactory : ISchemeHandlerFactory
    {
        public const string SchemeName = "customFileProtocol";

        public IResourceHandler Create(IBrowser browser, IFrame frame, string schemeName, IRequest request)
        {
            return new CustomProtocolSchemeHandler();
        }
    }
}

然后注册一下打电话之前Cef.初始化：

var settings = new CefSettings
{
  BrowserSubprocessPath = GetCefExecutablePath()
};

settings.RegisterScheme(new CefCustomScheme
{
  SchemeName = CustomProtocolSchemeHandlerFactory.SchemeName,
  SchemeHandlerFactory = new CustomProtocolSchemeHandlerFactory()
});