UriHelper.cs 中的实现源码：

// <summary>
/// Returns the combined components of the request URL in a fully un-escaped form (except for the QueryString)
/// suitable only for display. This format should not be used in HTTP headers or other HTTP operations.
/// </summary>
/// <param name="request">The request to assemble the uri pieces from.</param>
/// <returns>The combined components of the request URL in a fully un-escaped form (except for the QueryString)
/// suitable only for display.</returns>
public static string GetDisplayUrl(this HttpRequest request)
{
    var scheme = request.Scheme ?? string.Empty;
    var host = request.Host.Value ?? string.Empty;
    var pathBase = request.PathBase.Value ?? string.Empty;
    var path = request.Path.Value ?? string.Empty;
    var queryString = request.QueryString.Value ?? string.Empty;

    // PERF: Calculate string length to allocate correct buffer size for StringBuilder.
    var length = scheme.Length + SchemeDelimiter.Length + host.Length
        + pathBase.Length + path.Length + queryString.Length;

    return new StringBuilder(length)
        .Append(scheme)
        .Append(SchemeDelimiter)
        .Append(host)
        .Append(pathBase)
        .Append(path)
        .Append(queryString)
        .ToString();
}