这篇文章主要介绍了CefSharp过滤图片RequestHandler问题，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教

C# CefSharp 过滤 RequestHandler 图片

1、方式一

ChromiumWebBrowser 实现 IRequestHandler

具体内同参照 附录；将 OnBeforeResourceLoad方法替换成2中的内容，很简单；

2、方式二

继承集成默认的抽象类 DefaultRequestHandler

 internal class RequestHandler : DefaultRequestHandler 
    {

        public  override CefReturnValue  OnBeforeResourceLoad(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IRequestCallback callback)
        {

            if (request.ResourceType == ResourceType.Image)
                return CefReturnValue.Cancel;

            return CefReturnValue.Continue;
        }
}

对比实现接口方式和继承集成默认的抽象类，发现抽象类可以只实现相关的处理方法更加灵活。而若采用IRequestHandler需要实现RequestHandler接口中的所有方法，否则抛出未实现异常；

和其他网上从Response环节过滤资源图片的方法不同，这里谈到的方法在请求图片资源之前，可以节省流量，加快页面访问速度等。

附录：

using System;
using CefSharp.Example.Filters;
using System.Security.Cryptography.X509Certificates;
using System.Collections.Generic;
using System.Text;
using CefSharp.Handler;

namespace CefSharp.Example.Handlers
{
    /// <summary>
    /// DefaultRequestHandler provides a base class for you to inherit from 
    /// you only need to implement the methods that are relevant to you. 
    /// If you implement the IRequestHandler interface you will need to
    /// implement every method
    /// </summary>
    public class RequestHandler : IRequsetHandler
    {
        public static readonly string VersionNumberString = String.Format("Chromium: {0}, CEF: {1}, CefSharp: {2}",
            Cef.ChromiumVersion, Cef.CefVersion, Cef.CefSharpVersion);

        private Dictionary<UInt64, MemoryStreamResponseFilter> responseDictionary = new Dictionary<UInt64, MemoryStreamResponseFilter>();

        public override bool OnBeforeBrowse(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, bool userGesture, bool isRedirect)
        {
            return false;
        }

        public override bool OnOpenUrlFromTab(IWebBrowser browserControl, IBrowser browser, IFrame frame, string targetUrl, WindowOpenDisposition targetDisposition, bool userGesture)
        {
            return false;
        }

        public override bool OnCertificateError(IWebBrowser browserControl, IBrowser browser, CefErrorCode errorCode, string requestUrl, ISslInfo sslInfo, IRequestCallback callback)
        {
            //NOTE: If you do not wish to implement this method returning false is the default behaviour
            // We also suggest you explicitly Dispose of the callback as it wraps an unmanaged resource.
            //callback.Dispose();
            //return false;

            //NOTE: When executing the callback in an async fashion need to check to see if it's disposed
            if (!callback.IsDisposed)
            {
                using (callback)
                {
                    //To allow certificate
                    //callback.Continue(true);
                    //return true;
                }
            }

            return false;
        }

        public override void OnPluginCrashed(IWebBrowser browserControl, IBrowser browser, string pluginPath)
        {
            // TODO: Add your own code here for handling scenarios where a plugin crashed, for one reason or another.
        }

        public override CefReturnValue OnBeforeResourceLoad(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IRequestCallback callback)
        {
            Uri url;
            if (Uri.TryCreate(request.Url, UriKind.Absolute, out url) == false)
            {
                //If we're unable to parse the Uri then cancel the request
                // avoid throwing any exceptions here as we're being called by unmanaged code
                return CefReturnValue.Cancel;
            }

            //Example of how to set Referer
            // Same should work when setting any header

            // For this example only set Referer when using our custom scheme
            if (url.Scheme == CefSharpSchemeHandlerFactory.SchemeName)
            {
                //Referrer is now set using it's own method (was previously set in headers before)
                request.SetReferrer("http://google.com", ReferrerPolicy.Default);
            }

            //Example of setting User-Agent in every request.
            //var headers = request.Headers;

            //var userAgent = headers["User-Agent"];
            //headers["User-Agent"] = userAgent + " CefSharp";

            //request.Headers = headers;

            //NOTE: If you do not wish to implement this method returning false is the default behaviour
            // We also suggest you explicitly Dispose of the callback as it wraps an unmanaged resource.
            //callback.Dispose();
            //return false;

            //NOTE: When executing the callback in an async fashion need to check to see if it's disposed
            if (!callback.IsDisposed)
            {
                using (callback)
                {
                    if (request.Method == "POST")
                    {
                        using (var postData = request.PostData)
                        {
                            if(postData != null)
                            { 
                                var elements = postData.Elements;

                                var charSet = request.GetCharSet();

                                foreach (var element in elements)
                                {
                                    if (element.Type == PostDataElementType.Bytes)
                                    {
                                        var body = element.GetBody(charSet);
                                    }
                                }
                            }
                        }
                    }

                    //Note to Redirect simply set the request Url
                    //if (request.Url.StartsWith("https://www.google.com", StringComparison.OrdinalIgnoreCase))
                    //{
                    //    request.Url = "https://github.com/";
                    /