implement HttpServerUtility.HtmlEncode

src/Microsoft.AspNetCore.SystemWebAdapters/HttpServerUtility.cs

@@ -3,7 +3,9 @@
 
 using System.Collections.Specialized;
 using System.ComponentModel;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
+using System.Net;
 using System.Web.Hosting;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.SystemWebAdapters;
@@ -32,6 +34,11 @@ public string MapPath(string? path)
 
     public void ClearError() => _context.AsSystemWeb().ClearError();
 
+    [return: NotNullIfNotNull(nameof(value))]
+    public string? HtmlEncode(string? value) => WebUtility.HtmlEncode(value);
+
+    public void HtmlEncode(string? value, TextWriter output) => WebUtility.HtmlEncode(value, output);
+
     /// <summary>
     /// This method is similar to <see cref="WebEncoders.Base64UrlDecode(string)"/> but handles the trailing character that <see cref="UrlTokenEncode(byte[])"/>
     /// appends to the string.

src/Microsoft.AspNetCore.SystemWebAdapters/HttpServerUtilityBase.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics.CodeAnalysis;
+using System.IO;
 
 namespace System.Web;
 
@@ -10,6 +11,10 @@ public class HttpServerUtilityBase
 {
     public virtual string MachineName => throw new NotImplementedException();
 
+    public virtual string? HtmlEncode(string? value) => throw new NotImplementedException();
+
+    public virtual void HtmlEncode(string? value, TextWriter output) => throw new NotImplementedException();
+
     public virtual string MapPath(string path) => throw new NotImplementedException();
 
     public virtual Exception? GetLastError() => throw new NotImplementedException();

src/Microsoft.AspNetCore.SystemWebAdapters/HttpServerUtilityWrapper.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.IO;
+
 namespace System.Web;
 
 public class HttpServerUtilityWrapper : HttpServerUtilityBase
@@ -20,6 +22,10 @@ public HttpServerUtilityWrapper(HttpServerUtility utility)
 
     public override string MachineName => _utility.MachineName;
 
+    public override string? HtmlEncode(string? value) => _utility.HtmlEncode(value);
+
+    public override void HtmlEncode(string? value, TextWriter output) => _utility.HtmlEncode(value, output);
+
     public override string MapPath(string path) => _utility.MapPath(path);
 
     public override byte[]? UrlTokenDecode(string input) => HttpServerUtility.UrlTokenDecode(input);