XML(de)序列化无效字符串在c#中不一致？

Question

在C#(.net 4.0和4.5/vs2010和vs12)中,当我使用XMLSerializer序列化包含具有非法字符的字符串的对象时,不会引发错误.但是,当我反序列化该结果时,会抛出"无效字符"错误.

        // add to XML
        Items items = new Items();
        items.Item = "\v hello world"; // contains "illegal" character \v

        // variables
        System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(Items));
        string tmpFile = Path.GetTempFileName();

        // serialize
        using (FileStream tmpFileStream = new FileStream(tmpFile, FileMode.Open, FileAccess.ReadWrite))
        {
            serializer.Serialize(tmpFileStream, items);
        }
        Console.WriteLine("Success! XML serialized in file " + tmpFile);

        // deserialize
        Items result = null;
        using (FileStream plainTextFile = new FileStream(tmpFile, FileMode.Open, FileAccess.Read))
        {
            result = (Items)serializer.Deserialize(plainTextFile); //FAILS here
        }

        Console.WriteLine(result.Item);

"Items"只是由xsd/c Items.xsd自动生成的一个小类.Items.xsd只不过是一个包含一个子元素(Item)的根元素(Items):

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
    <xs:element name="Items">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="Item" type="xs:string" />
            </xs:sequence>
        </xs:complexType>
    </xs:element>
</xs:schema>

反序列化期间抛出的错误是

未处理的异常:System.InvalidOperationException:XML文档中存在错误(3,12).---> System.Xml.XmlException:'♂',十六进制值0x0B,是无效字符.第3行,第12位.

序列化的XML文件包含第3行:

<Item>&#xB; hello world</Item>

我知道\ v - > 是一个非法字符,但为什么XMLSerialize允许它被序列化(没有错误)？我发现它与.NET不一致,它允许我序列化一些没有问题的东西,只是发现我无法反序列化它.

是否有解决方案,以便XMLSerializer在序列化之前自动删除非法字符,还是可以指示反序列化忽略非法字符？

目前我通过将文件内容作为字符串读取来解决它,替换"手动"非法字符然后反序列化它...但我发现这是一个丑陋的黑客/解决方法.

Answer 1

1.

您可以设置XmlWriterSettings的CheckCharacters属性,以避免编写非法字符.(Serialize方法会抛出异常)

using (FileStream tmpFileStream = new FileStream(tmpFile, FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
    var writer = XmlWriter.Create(tmpFileStream, new XmlWriterSettings() { CheckCharacters = true});
    serializer.Serialize(writer, items);
}

2.

您可以创建自己的XmlTextWriter,以在序列化时过滤掉不需要的字符

using (FileStream tmpFileStream = new FileStream(tmpFile, FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
    var writer = new MyXmlWriter(tmpFileStream);
    serializer.Serialize(writer, items);
}

public class MyXmlWriter : XmlTextWriter
{
    public MyXmlWriter(Stream s) : base(s, Encoding.UTF8)
    {
    }

    public override void WriteString(string text)
    {
        string newText = String.Join("", text.Where(c => !char.IsControl(c)));
        base.WriteString(newText);
    }
}

3.

通过创建自己的XmlTextReader,您可以在反序列化时过滤掉不需要的字符

using (FileStream plainTextFile = new FileStream(tmpFile, FileMode.Open, FileAccess.Read))
{
    var reader = new MyXmlReader(plainTextFile);
    result = (SomeObject)serializer.Deserialize(reader); 
}

public class MyXmlReader : XmlTextReader
{
    public MyXmlReader(Stream s) : base(s)
    {
    }

    public override string ReadString()
    {
        string text =  base.ReadString();
        string newText = String.Join("", text.Where(c => !char.IsControl(c)));
        return newText;
    }
}

4.

您可以将XmlReaderSettings's CheckCharacters属性设置为false.反序列化现在可以顺利进行.(你会\v回来的.)

using (FileStream plainTextFile = new FileStream(tmpFile, FileMode.Open, FileAccess.Read))
{
    var reader = XmlReader.Create(plainTextFile, new XmlReaderSettings() { CheckCharacters = false });
    result = (SomeObject)serializer.Deserialize(reader); 
}