使用 XmlWriter 迭代构建 XML 文件

发布于 2024-10-09 17:30:41 字数 609 浏览 1 评论 0原文

我希望能够使用 XmlWriter（C#、.NET）创建 XML 文档，其中多次调用生成 XML 的方法，然后调用一次最终方法来关闭所有内容。当我尝试多次调用此方法时：

private void SiblingGenerator(List<XmlNode> XMLList, XmlWriter textWriter,
    string newPath, FileInfo fi)
{
    if (fi.Length == 0)
    {
        MessageBox.Show("file doesn't exist");

        textWriter.WriteStartDocument();
        textWriter.WriteStartElement("batch");
        //...
    }

    // ...
}

...它返回一个错误，指出 WriteStartDocument 需要是第一次调用。

似乎对 textWriter 的调用实际上并未被写入，因为在每次后续调用中，文档都会重新开始。

谁能告诉我为什么会发生这种情况？

原文

I want to be able to use XmlWriter (C#, .NET) to create an XML document with multiple calls to a method that generates XML and then a single call to a final method that closes everything off. When I try to call this method multiple times:

private void SiblingGenerator(List<XmlNode> XMLList, XmlWriter textWriter,
    string newPath, FileInfo fi)
{
    if (fi.Length == 0)
    {
        MessageBox.Show("file doesn't exist");

        textWriter.WriteStartDocument();
        textWriter.WriteStartElement("batch");
        //...
    }

    // ...
}

...it returns an error saying that WriteStartDocument needs to be the first call.

It seems like the calls to the textWriter aren't actually being written because on each subsequent call the document starts over again.

Can anyone tell me why this is happening?

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逆光下的微笑 2024-10-16 17:30:41

XmlWriter 只能转发，不能重复使用。您不应在此类的同一实例上多次调用 WriteStartDocument。因为它是方法的参数，所以调用者必须负责处理编写器的生命周期。

using (var writer = XmlWriter.Create("foo.xml"))
{
    SiblingGenerator(XMLList, writer, newPath, fi);
}

如果您需要多次重用 SiblingGenerator 函数，那么您可能需要外部化 WriteStartDocument 方法的调用：

using (var writer = XmlWriter.Create("foo.xml"))
{
    writer.WriteStartDocument();
    SiblingGenerator(XMLList, writer, newPath, fi);
    SiblingGenerator(XMLList, writer, newPath, fi);
    ...
    writer.WriteEndDocument();
}

A XmlWriter is forward only and cannot be reused. You shouldn't call WriteStartDocument multiple times on the same instance of this class. Because it is an argument of your method it is the caller that must take care of handling the life-cycle of the writer.

using (var writer = XmlWriter.Create("foo.xml"))
{
    SiblingGenerator(XMLList, writer, newPath, fi);
}

If you need to reuse the SiblingGenerator function multiple times then you might want to externalize the call of the WriteStartDocument method:

using (var writer = XmlWriter.Create("foo.xml"))
{
    writer.WriteStartDocument();
    SiblingGenerator(XMLList, writer, newPath, fi);
    SiblingGenerator(XMLList, writer, newPath, fi);
    ...
    writer.WriteEndDocument();
}

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