C# 使用override void WriteEndElement（）时如何使用XmlWriterSettings（）？

我使用的是一个遗留应用程序，它不导入缩写的空xml元素。例如：

坏空：

<foo />

和客户端代码：

                    var x_settings = new XmlWriterSettings();
                    x_settings.NewLineChars = Environment.NewLine;
                    x_settings.NewLineOnAttributes = true;
                    x_settings.NewLineHandling = NewLineHandling.Replace;
                    x_settings.CloseOutput = true;
                    x_settings.Indent = true;
                    x_settings.NewLineOnAttributes = true;

                    //var memOut = new MemoryStream();
                    var writer = new XmlTextWriterFull(outputFilename, Encoding.UTF8); //Or the encoding of your choice
                    var x_serial = new XmlSerializer(typeof(YOUR_OBJECT_TYPE));
                    x_serial.Serialize(writer, YOUR_OBJECT_INSTANCE);

                    writer.Close();

但是，如果仔细观察，客户机代码中永远不会使用

XmlWriterSettings

。因此，xml输出的格式非常糟糕。我的问题是：如何调整上述代码以接受

XmlWriterSettings

工厂创建方法和密封/内部/抽象类的使用使得实现重写变得困难

我将接受另一种解决方案，我不同意我的上述解决方案

• 解决方案

步骤1：在解决方案中创建以下类：

public class XmlTextWriterFull : XmlTextWriter
{
    public XmlTextWriterFull(TextWriter sink) : base(sink)
    {
        Formatting = Formatting.Indented;
    }

    public override void WriteEndElement()
    {
        base.WriteFullEndElement();
    }
}

步骤2：添加以下客户端代码。确保使用您正在使用的类和实例替换您的\u对象\u类型和\u对象\u实例：

TextWriter streamWriter = new StreamWriter(outputFilename);
var writer = new XmlTextWriterFull(streamWriter);

var x_serial = new XmlSerializer(typeof (YOUR_OBJECT_TYPE));
x_serial.Serialize(writer, YOUR_OBJECT_INSTANCE);

writer.Close();

上述解决方法将生成以下空xml元素格式：

<foo>
</foo>

此解决方案的问题在于它添加了换行符（请注意，元素位于单独的行上）。这对您来说可能是可以接受的，但会导致我的旧版应用程序出现问题。

如何

从中获取可怕的

XmlWrappingWriter

类（为了简洁起见，我省略了代码）

这样，我们可以创建一个子类，如下所示（非常类似于您原来的子类）：

然后可以这样调用它（同样非常类似）：

在我的例子中，一个以前被渲染为

<Foo>
</Foo>

可用于将

XmlWriter设置应用于
XmlWriter
。我无法让它像我所希望的那样工作（例如，缩进从未工作过），并且在反编译代码时，似乎并不是所有的设置都与这个特定的方法一起使用，因此我的调用代码只是在
输出文件中传递（某种类型的流也可以工作）。
另一个选项

public class XmlCustomTextWriter : XmlTextWriter
{
    private TextWriter _tw = null;

    public XmlCustomTextWriter(TextWriter sink)
        : base(sink)
    {
        _tw = sink;
        Formatting = Formatting.Indented;
        Indentation = 0;
    }

    public void OutputElement(string name, string value)
    {
        WriteStartElement(name);
        string nl = _tw.NewLine;
        _tw.NewLine = "";
        WriteString(value);
        WriteFullEndElement();
        _tw.NewLine = nl;
    }
}

您在问题中给出的变通解决方案添加了额外的换行符（启用缩进时），因为我们告诉编写者将此元素视为具有子元素

下面是我如何修改您的解决方法来动态操作缩进，以避免那些额外的换行

public class XmlTextWriterFull : XmlTextWriter
{
    public XmlTextWriterFull(TextWriter sink)
        : base(sink)
    {
        Formatting = Formatting.Indented;
    }

    private bool inElement = false;

    public override void WriteStartElement(string prefix, string localName, string ns)
    {
        base.WriteStartElement(prefix, localName, ns);

        // Remember that we're in the process of defining an element.
        // As soon as a child element is closed, this flag won't be true anymore and we'll know to avoid messing with the indenting.
        this.inElement = true;
    }

    public override void WriteEndElement()
    {
        if (!this.inElement)
        {
            // The element being closed has child elements, so we should just let the writer use it's default behavior.
            base.WriteEndElement();
        }
        else
        {
            // It looks like the element doesn't have children, and we want to avoid emitting a self-closing tag.
            // First, let's temporarily disable any indenting, then force the full closing element tag.
            var prevFormat = this.Formatting;
            this.Formatting = Formatting.None;
            base.WriteFullEndElement();
            this.Formatting = prevFormat;
            this.inElement = false;
        }
    }
}

把这个留在这里，以防有人需要它；因为上面的答案没有一个能帮我解决这个问题，或者看起来有点过分了

    FileStream fs = new FileStream("file.xml", FileMode.Create);
    XmlWriterSettings settings = new XmlWriterSettings();
    settings.Indent = true;
    XmlWriter w = XmlWriter.Create(fs, settings);
    w.WriteStartDocument();
    w.WriteStartElement("tag1");

        w.WriteStartElement("tag2");
        w.WriteAttributeString("attr1", "val1");
        w.WriteAttributeString("attr2", "val2");
        w.WriteFullEndElement();

    w.WriteEndElement();
    w.WriteEndDocument();
    w.Flush();
    fs.Close();

诀窍是设置XmlWriterSettings.Indent=true并将其添加到XmlWriter中

编辑：
或者，您也可以使用

w.Formatting = Formatting.Indented;

不要添加XmlWriterSettings。
下面的代码片段强制在同一行上打印结束标记（很抱歉，对于vb版本，使用C#重写相同的标记应该很容易）：

不知道它是否解决了这个特殊情况，但您可以使用XmlWriter.Create重载，该重载接受现有的writer和设置。您可以将自己的writer实现传递给该方法。据我所知，它允许您“向底层XmlWriter对象添加其他功能”，但我不知道这是否包括格式设置。我无法回答自己的问题。但我确实找到了一个可以接受的解决办法。我会把它贴在这里，希望能帮助别人；然而，我仍然希望我的问题得到解决。我的变通方法不使用我想要的XmlWriterSettings。更新：我的旧版应用程序不接受上述变通方法，因为完整标记插入了换行元素；因此，标记显示在单独的行上。我发布了一个悬赏，想看看我是否能吸引更多的注意力。这有点蹩脚，但你可以输出后处理你的输出，并用代码替换
\s+你有机会看看我的答案吗？我很有信心它会解决你的问题。
<Foo></Foo>

XmlWriter.Create(XmlWriter, XmlWriterSettings)

public class XmlCustomTextWriter : XmlTextWriter
{
    private TextWriter _tw = null;

    public XmlCustomTextWriter(TextWriter sink)
        : base(sink)
    {
        _tw = sink;
        Formatting = Formatting.Indented;
        Indentation = 0;
    }

    public void OutputElement(string name, string value)
    {
        WriteStartElement(name);
        string nl = _tw.NewLine;
        _tw.NewLine = "";
        WriteString(value);
        WriteFullEndElement();
        _tw.NewLine = nl;
    }
}

public class XmlTextWriterFull : XmlTextWriter
{
    public XmlTextWriterFull(TextWriter sink)
        : base(sink)
    {
        Formatting = Formatting.Indented;
    }

    private bool inElement = false;

    public override void WriteStartElement(string prefix, string localName, string ns)
    {
        base.WriteStartElement(prefix, localName, ns);

        // Remember that we're in the process of defining an element.
        // As soon as a child element is closed, this flag won't be true anymore and we'll know to avoid messing with the indenting.
        this.inElement = true;
    }

    public override void WriteEndElement()
    {
        if (!this.inElement)
        {
            // The element being closed has child elements, so we should just let the writer use it's default behavior.
            base.WriteEndElement();
        }
        else
        {
            // It looks like the element doesn't have children, and we want to avoid emitting a self-closing tag.
            // First, let's temporarily disable any indenting, then force the full closing element tag.
            var prevFormat = this.Formatting;
            this.Formatting = Formatting.None;
            base.WriteFullEndElement();
            this.Formatting = prevFormat;
            this.inElement = false;
        }
    }
}

    FileStream fs = new FileStream("file.xml", FileMode.Create);
    XmlWriterSettings settings = new XmlWriterSettings();
    settings.Indent = true;
    XmlWriter w = XmlWriter.Create(fs, settings);
    w.WriteStartDocument();
    w.WriteStartElement("tag1");

        w.WriteStartElement("tag2");
        w.WriteAttributeString("attr1", "val1");
        w.WriteAttributeString("attr2", "val2");
        w.WriteFullEndElement();

    w.WriteEndElement();
    w.WriteEndDocument();
    w.Flush();
    fs.Close();

w.Formatting = Formatting.Indented;

Imports System.Xml
Imports System.IO
Public Class CustomXmlTextWriter
    Inherits XmlTextWriter

    Public Sub New(ByRef baseWriter As TextWriter)
        MyBase.New(baseWriter)
        Formatting = Xml.Formatting.Indented
    End Sub

    Public Overrides Sub WriteEndElement()
        If Not (Me.WriteState = Xml.WriteState.Element) Then
            MyBase.WriteEndElement()
        Else
            Formatting = Xml.Formatting.None
            MyBase.WriteFullEndElement()
            Formatting = Xml.Formatting.Indented
        End If
    End Sub

End Class