如何通过StAX修改巨大的XML文件？ [英] How to modify a huge XML file by StAX?

问题描述

我有一个巨大的XML（~2GB），我需要添加新元素并修改旧元素。例如，我有：

I have a huge XML (~2GB) and I need to add new Elements and modify the old ones. For example, I have:

<books>
    <book>....</book>
    ...
    <book>....</book>
</books>

想得到：

<books>
   <book>
      <index></index>
      ....
   </book>
   ...
   <book>
      <index></index>
      ....
   </book>
</books>

我使用了以下代码：

XMLInputFactory inFactory = XMLInputFactory.newInstance();
XMLEventReader eventReader = inFactory.createXMLEventReader(new FileInputStream(file));
XMLOutputFactory factory = XMLOutputFactory.newInstance();
XMLStreamWriter writer = factory.createXMLStreamWriter(new FileWriter(file, true));
while (eventReader.hasNext()) {
   XMLEvent event = eventReader.nextEvent();
   if (event.getEventType() == XMLEvent.START_ELEMENT) {
      if (event.asStartElement().getName().toString().equalsIgnoreCase("book")) {
          writer.writeStartElement("index");
          writer.writeEndElement();
       }
    }
}
writer.close();

但结果如下：

<books>
   <book>....</book>
   ....
   <book>....</book>
</books><index></index>

任何想法？

推荐答案

试试这个

    XMLInputFactory inFactory = XMLInputFactory.newInstance();
    XMLEventReader eventReader = inFactory.createXMLEventReader(new FileInputStream("1.xml"));
    XMLOutputFactory factory = XMLOutputFactory.newInstance();
    XMLEventWriter writer = factory.createXMLEventWriter(new FileWriter(file));
    XMLEventFactory eventFactory = XMLEventFactory.newInstance();
    while (eventReader.hasNext()) {
        XMLEvent event = eventReader.nextEvent();
        writer.add(event);
        if (event.getEventType() == XMLEvent.START_ELEMENT) {
            if (event.asStartElement().getName().toString().equalsIgnoreCase("book")) {
                writer.add(eventFactory.createStartElement("", null, "index"));
                writer.add(eventFactory.createEndElement("", null, "index"));
            }
        }
    }
    writer.close();

注释

新的FileWriter（文件，真的）附加到文件的末尾，你几乎不需要它

new FileWriter(file, true) is appending to the end of the file, you hardly really need it

equalsIgnoreCase（book）是个坏主意，因为XML区分大小写

equalsIgnoreCase("book") is bad idea because XML is case-sensitive

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