Java 8 - 使用 Stax 拆分巨大的 XML 文件会产生意想不到的结果

Question

当拆分一个巨大的 XML 文件时，我看到了一个使用 Stax 和 Transformer.transform() 的非常好的解决方案。很好，但是我 看到一些标签丢失了。 为什么会这样？

名称为...的XML 文件给出以下结果。在 EVENT 场合元素标签被省略。

Element: <?xml version="1.0" encoding="UTF-8"?><car><name>car1</name></car>
Element: <?xml version="1.0" encoding="UTF-8"?><name>car2</name>
Element: <?xml version="1.0" encoding="UTF-8"?><car><name>car3</name></car>
Element: <?xml version="1.0" encoding="UTF-8"?><name>car4</name>

如何获得正确的元素？这与 transform(s, r) 干扰输入流读取有关吗？

这是我的代码（我在 this one 等很多地方看到过）。使用 StringReader 或 FileReader 时没有变化。

我预料到这个：循环{前进到开始标签；访问该元素} 我看到的是：第一个：元素+第二个：元素的一部分+重复。

String testCars = "<root><car><name>car1</name></car><car><name>car2</name></car><car><name>car3</name></car><car><name>car4</name></car></root>";
String element = "car";
try {
    XMLInputFactory factory = XMLInputFactory.newInstance();
    XMLStreamReader streamReader = factory.createXMLStreamReader(new StringReader(testCars));
    streamReader.nextTag();
    TransformerFactory tf = TransformerFactory.newInstance();
    Transformer t = tf.newTransformer();
    while(streamReader.nextTag() == XMLStreamConstants.START_ELEMENT) {
            StringWriter writer = new StringWriter();
            StreamResult result = new StreamResult(writer);
            t.transform(new StAXSource(streamReader), result);
            System.out.println("Element: " + writer.toString());
    }
} catch (Exception e) { ... }

Answer 1

感谢 Andreas，这是解决方案：

String testCars = "<root><car><name>car1</name></car><other><something>Unknown</something></other><car><name>car2</name></car></root>";
XMLInputFactory factory = XMLInputFactory.newInstance();
try {
    XMLStreamReader streamReader = factory.createXMLStreamReader(new StringReader(testCars));
    streamReader.nextTag();
    TransformerFactory tf = TransformerFactory.newInstance();
    Transformer t = tf.newTransformer();
    streamReader.nextTag();
    while ( streamReader.isStartElement() ||
          ( ! streamReader.hasNext() && streamReader.nextTag() == XMLStreamConstants.START_ELEMENT)) {
        StringWriter writer = new StringWriter();
        StreamResult result = new StreamResult(writer);
        t.transform(new StAXSource(streamReader), result);
        System.out.println( "XmlElement: " + writer.toString());
    }
} catch (Exception e) { ... }

输入是：

<root>
  <car>
    <name>car1</name>
  </car>
  <other>
    <something>Unknown</something>
  </other>
  <car>
    <name>car2</name>
  </car>
</root>

输出为：

XmlElement: <?xml version="1.0" encoding="UTF-8"?><car><name>car1</name></car>
XmlElement: <?xml version="1.0" encoding="UTF-8"?><other><something>Unknown</something></other>
XmlElement: <?xml version="1.0" encoding="UTF-8"?><car><name>car2</name></car>

Java 8 - 使用 Stax 拆分巨大的 XML 文件会产生意想不到的结果

Java 8 - Split huge XML file using Stax gives unexpected results

java

stax