逃脱在C＃中无效XML字符 [英] Escape invalid XML characters in C#

问题描述

我有一个包含无效XML字符的字符串。我怎样才能逃脱（或删除）无效XML字符之前我解析字符串？

I have a string that contains invalid XML characters. How can I escape (or remove) invalid XML characters before I parse the string?

推荐答案

由于方法来消除，我建议你使用无效XML字符<一href="http://msdn.microsoft.com/en-us/library/system.xml.xmlconvert.isxmlchar%28v=vs.100%29.aspx">XmlConvert.IsXmlChar方法。它，因为.NET Framework 4的加入，是psented在Silverlight太$ P $。这里是小样本：

As the way to remove invalid XML characters I suggest you to use XmlConvert.IsXmlChar method. It was added since .NET Framework 4 and is presented in Silverlight too. Here is the small sample:

void Main() {
    string content = "\v\f\0";
    Console.WriteLine(IsValidXmlString(content)); // False

    content = RemoveInvalidXmlChars(content);
    Console.WriteLine(IsValidXmlString(content)); // True
}

static string RemoveInvalidXmlChars(string text) {
    var validXmlChars = text.Where(ch => XmlConvert.IsXmlChar(ch)).ToArray();
    return new string(validXmlChars);
}

static bool IsValidXmlString(string text) {
    try {
        XmlConvert.VerifyXmlChars(text);
        return true;
    } catch {
        return false;
    }
}

和为逃避我建议你使用<无效XML字符的方式href="http://msdn.microsoft.com/en-us/library/system.xml.xmlconvert.en$c$cname%28v=vs.100%29.aspx">XmlConvert.En$c$cName方法。这里是小样本：

And as the way to escape invalid XML characters I suggest you to use XmlConvert.EncodeName method. Here is the small sample:

void Main() {
    const string content = "\v\f\0";
    Console.WriteLine(IsValidXmlString(content)); // False

    string encoded = XmlConvert.EncodeName(content);
    Console.WriteLine(IsValidXmlString(encoded)); // True

    string decoded = XmlConvert.DecodeName(encoded);
    Console.WriteLine(content == decoded); // True
}

static bool IsValidXmlString(string text) {
    try {
        XmlConvert.VerifyXmlChars(text);
        return true;
    } catch {
        return false;
    }
}

更新： 应该提到的是，编码操作产生的字符串的长度为大于或等于源串的长度。当你存储在数据库中的连接codeD字符串长度的限制字符串列和验证源字符串长度在你的应用程序，以适应数据列限制，它可以是非常重要的。

Update: It should be mentioned that the encoding operation produces a string with a length is greater or equal than a length of a source string. It can be important when you store a encoded string in a database in a string column with length limitation and validate source string length in your app to fit data column limitation.

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