这两种方法在 Windows Phone 上的实现确实不同。
WebUtility.HtmlDecode:
public static void HtmlDecode(string value, TextWriter output)
{
if (value != null)
{
if (output == null)
{
throw new ArgumentNullException("output");
}
if (!StringRequiresHtmlDecoding(value))
{
output.Write(value);
}
else
{
int length = value.Length;
for (int i = 0; i < length; i++)
{
bool flag;
uint num4;
char ch = value[i];
if (ch != '&')
{
goto Label_01B6;
}
int num3 = value.IndexOfAny(_htmlEntityEndingChars, i + 1);
if ((num3 <= 0) || (value[num3] != ';'))
{
goto Label_01B6;
}
string entity = value.Substring(i + 1, (num3 - i) - 1);
if ((entity.Length <= 1) || (entity[0] != '#'))
{
goto Label_0188;
}
if ((entity[1] == 'x') || (entity[1] == 'X'))
{
flag = uint.TryParse(entity.Substring(2), NumberStyles.AllowHexSpecifier, NumberFormatInfo.InvariantInfo, out num4);
}
else
{
flag = uint.TryParse(entity.Substring(1), NumberStyles.Integer, NumberFormatInfo.InvariantInfo, out num4);
}
if (flag)
{
switch (_htmlDecodeConformance)
{
case UnicodeDecodingConformance.Strict:
flag = (num4 < 0xd800) || ((0xdfff < num4) && (num4 <= 0x10ffff));
goto Label_0151;
case UnicodeDecodingConformance.Compat:
flag = (0 < num4) && (num4 <= 0xffff);
goto Label_0151;
case UnicodeDecodingConformance.Loose:
flag = num4 <= 0x10ffff;
goto Label_0151;
}
flag = false;
}
Label_0151:
if (!flag)
{
goto Label_01B6;
}
if (num4 <= 0xffff)
{
output.Write((char) num4);
}
else
{
char ch2;
char ch3;
ConvertSmpToUtf16(num4, out ch2, out ch3);
output.Write(ch2);
output.Write(ch3);
}
i = num3;
goto Label_01BD;
Label_0188:
i = num3;
char ch4 = HtmlEntities.Lookup(entity);
if (ch4 != '\0')
{
ch = ch4;
}
else
{
output.Write('&');
output.Write(entity);
output.Write(';');
goto Label_01BD;
}
Label_01B6:
output.Write(ch);
Label_01BD:;
}
}
}
}
HttpUtility.HtmlDecode:
public static string HtmlDecode(string html)
{
if (html == null)
{
return null;
}
if (html.IndexOf('&') < 0)
{
return html;
}
StringBuilder sb = new StringBuilder();
StringWriter writer = new StringWriter(sb, CultureInfo.InvariantCulture);
int length = html.Length;
for (int i = 0; i < length; i++)
{
char ch = html[i];
if (ch == '&')
{
int num3 = html.IndexOfAny(s_entityEndingChars, i + 1);
if ((num3 > 0) && (html[num3] == ';'))
{
string entity = html.Substring(i + 1, (num3 - i) - 1);
if ((entity.Length > 1) && (entity[0] == '#'))
{
try
{
if ((entity[1] == 'x') || (entity[1] == 'X'))
{
ch = (char) int.Parse(entity.Substring(2), NumberStyles.AllowHexSpecifier, CultureInfo.InvariantCulture);
}
else
{
ch = (char) int.Parse(entity.Substring(1), CultureInfo.InvariantCulture);
}
i = num3;
}
catch (FormatException)
{
i++;
}
catch (ArgumentException)
{
i++;
}
}
else
{
i = num3;
char ch2 = HtmlEntities.Lookup(entity);
if (ch2 != '\0')
{
ch = ch2;
}
else
{
writer.Write('&');
writer.Write(entity);
writer.Write(';');
continue;
}
}
}
}
writer.Write(ch);
}
return sb.ToString();
}
有趣的是,WP7 上不存在 WebUtility。此外,WebUtility 的 WP8 实现与桌面实现相同。的桌面实现HttpUtility.HtmlDecode
只是WebUtility.HtmlDecode
. 最后但同样重要的是,Silverlight 5 具有与HttpUtility.HtmlDecode
Windows Phone 相同的实现,但没有实现 WebUtility。
从那里,我可以大胆猜测:由于 Windows Phone 7 运行时基于 Silverlight,WP7 继承了 Silverlight 版本HttpUtility.HtmlDecode
,并且 WebUtility 不存在。然后是 WP8,它的运行时基于 WinRT。WinRT 带来了 WebUtility,并HttpUtility.HtmlDecode
保留了旧版本以确保与旧版 WP7 应用程序的兼容性。
至于知道你应该使用哪一个......如果你想针对 WP7,那么你别无选择,只能使用HttpUtility.HtmlDecode
. 如果您的目标是 WP8,那么只需选择其行为最适合您需求的方法。WebUtility 可能是面向未来的选择,以防万一微软决定在即将推出的 Windows Phone 版本中放弃 Silverlight 运行时。但我只是选择 HttpUtility 的实际选择,而不必担心手动支持您在问题中提出的示例。