在使用XDocument.Load()加载文件之前,如何测试文件以查看它是否是有效的XML文件？

using System.Xml;

public static bool IsValidXml(string xml)
{
    XmlReaderSettings settings = new XmlReaderSettings();
    settings.ValidationType = ValidationType.Schema;
    settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessInlineSchema;
    settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessSchemaLocation;
    settings.ValidationFlags |= XmlSchemaValidationFlags.ReportValidationWarnings;
    settings.ValidationEventHandler += new ValidationEventHandler(ValidationEventHandler);

    XmlReader reader = XmlReader.Create(new StringReader(xml), settings);

    try
    {
        while (reader.Read()) { }
        return true;
    }
    catch (XmlException)
    {
        return false;
    }
}

private static void ValidationEventHandler(object sender, ValidationEventArgs e)
{
    throw new ApplicationException("Invalid XML: " + e.Message);
}

using System.Xml;
using System.Xml.Schema;

public static bool IsValidXml(string xml)
{
    XmlReaderSettings settings = new XmlReaderSettings();
    settings.ValidationType = ValidationType.Schema;
    settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessInlineSchema;
    settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessSchemaLocation;
    settings.ValidationFlags |= XmlSchemaValidationFlags.ReportValidationWarnings;
    settings.ValidationEventHandler += new ValidationEventHandler(ValidationEventHandler);

    XmlSchemaSet schemaSet = new XmlSchemaSet();
    schemaSet.Add("http://www.w3.org/2001/XMLSchema", "http://www.w3.org/2001/XMLSchema.xsd");

    settings.Schemas = schemaSet;

    XmlReader reader = XmlReader.Create(new StringReader(xml), settings);

    try
    {
        while (reader.Read()) { }
        return true;
    }
    catch (XmlException)
    {
        return false;
    }
}

private static void ValidationEventHandler(object sender, ValidationEventArgs e)
{
    throw new ApplicationException("Invalid XML: " + e.Message);
}