虽然Gravatar服务的API(实际上，它实际上只是一个URL)非常简单，但是否有一个简单的帮助程序方法可以很好地反射(reflect)Gravatar的所有可用选项呢？
理想情况下，这将是
HtmlHelper扩展方法。我的目标是.NET4上的MVC2，但我想其他人也会对早期版本的选项感兴趣。
编辑实现也应允许为生成的HTML元素提供其他属性。
最佳答案
感谢您的回答。最后，我编写了自己的解决方案，因此我会将其发布在这里，以供其他可能认为有用的人使用。
如问题所示，它可以满足Gravatar目前支持的所有功能。
像这样使用它:
<%= Html.Gravatar(Model.User.EmailAddress) %>
我为任何选项提供了可选参数。这些可以组合。
// Use a specific image size (the default is 80px)
Html.Gravatar(Model.User.EmailAddress, size:64)
// Specify what image should appear if the email address is not
// associated with a Gravatar account
Html.Gravatar(Model.User.EmailAddress,
defaultImage:GravatarDefaultImage.Identicon)
// Specify the maximum rating allowed for images
Html.Gravatar(Model.User.EmailAddress, rating:GravatarRating.Pg)
// Add any additional HTML attributes for the <img /> tag
Html.Gravatar(Model.User.EmailAddress,
htmlAttributes:new { @class = "gravatar" })
这是代码:
using System;
using System.Diagnostics;
using System.Security.Cryptography;
using System.Text;
using System.Web.Mvc;
using System.Web.Routing;
namespace SampleNamespace
{
public static class HtmlHelperGravatar
{
/// <summary>
/// Creates HTML for an <c>img</c> element that presents a Gravatar icon.
/// </summary>
/// <param name="html">The <see cref="HtmlHelper"/> upon which this extension method is provided.</param>
/// <param name="email">The email address used to identify the icon.</param>
/// <param name="size">An optional parameter that specifies the size of the square image in pixels.</param>
/// <param name="rating">An optional parameter that specifies the safety level of allowed images.</param>
/// <param name="defaultImage">An optional parameter that controls what image is displayed for email addresses that don't have associated Gravatar icons.</param>
/// <param name="htmlAttributes">An optional parameter holding additional attributes to be included on the <c>img</c> element.</param>
/// <returns>An HTML string of the <c>img</c> element that presents a Gravatar icon.</returns>
public static string Gravatar(this HtmlHelper html,
string email,
int? size = null,
GravatarRating rating = GravatarRating.Default,
GravatarDefaultImage defaultImage = GravatarDefaultImage.MysteryMan,
object htmlAttributes = null)
{
var url = new StringBuilder("//www.gravatar.com/avatar/", 90);
url.Append(GetEmailHash(email));
var isFirst = true;
Action<string,string> addParam = (p,v) =>
{
url.Append(isFirst ? '?' : '&');
isFirst = false;
url.Append(p);
url.Append('=');
url.Append(v);
};
if (size != null)
{
if (size < 1 || size > 512)
throw new ArgumentOutOfRangeException("size", size, "Must be null or between 1 and 512, inclusive.");
addParam("s", size.Value.ToString());
}
if (rating != GravatarRating.Default)
addParam("r", rating.ToString().ToLower());
if (defaultImage != GravatarDefaultImage.Default)
{
if (defaultImage==GravatarDefaultImage.Http404)
addParam("d", "404");
else if (defaultImage==GravatarDefaultImage.Identicon)
addParam("d", "identicon");
if (defaultImage==GravatarDefaultImage.MonsterId)
addParam("d", "monsterid");
if (defaultImage==GravatarDefaultImage.MysteryMan)
addParam("d", "mm");
if (defaultImage==GravatarDefaultImage.Wavatar)
addParam("d", "wavatar");
}
var tag = new TagBuilder("img");
tag.MergeAttributes(new RouteValueDictionary(htmlAttributes));
tag.Attributes.Add("src", url.ToString());
if (size!=null)
{
tag.Attributes.Add("width", size.ToString());
tag.Attributes.Add("height", size.ToString());
}
return tag.ToString();
}
private static string GetEmailHash(string email)
{
if (email == null)
return new string('0', 32);
email = email.Trim().ToLower();
var emailBytes = Encoding.ASCII.GetBytes(email);
var hashBytes = new MD5CryptoServiceProvider().ComputeHash(emailBytes);
Debug.Assert(hashBytes.Length == 16);
var hash = new StringBuilder();
foreach (var b in hashBytes)
hash.Append(b.ToString("x2"));
return hash.ToString();
}
}
public enum GravatarRating
{
/// <summary>
/// The default value as specified by the Gravatar service. That is, no rating value is specified
/// with the request. At the time of authoring, the default level was <see cref="G"/>.
/// </summary>
Default,
/// <summary>
/// Suitable for display on all websites with any audience type. This is the default.
/// </summary>
G,
/// <summary>
/// May contain rude gestures, provocatively dressed individuals, the lesser swear words, or mild violence.
/// </summary>
Pg,
/// <summary>
/// May contain such things as harsh profanity, intense violence, nudity, or hard drug use.
/// </summary>
R,
/// <summary>
/// May contain hardcore sexual imagery or extremely disturbing violence.
/// </summary>
X
}
public enum GravatarDefaultImage
{
/// <summary>
/// The default value image. That is, the image returned when no specific default value is included
/// with the request. At the time of authoring, this image is the Gravatar icon.
/// </summary>
Default,
/// <summary>
/// Do not load any image if none is associated with the email hash, instead return an HTTP 404 (File Not Found) response.
/// </summary>
Http404,
/// <summary>
/// A simple, cartoon-style silhouetted outline of a person (does not vary by email hash).
/// </summary>
MysteryMan,
/// <summary>
/// A geometric pattern based on an email hash.
/// </summary>
Identicon,
/// <summary>
/// A generated 'monster' with different colors, faces, etc.
/// </summary>
MonsterId,
/// <summary>
/// Generated faces with differing features and backgrounds.
/// </summary>
Wavatar
}
}