我需要解析一个xml文件,无论其中的标签是什么,并读取其所有叶子的文本(仅文本元素) . 我正在使用StAX,但似乎没有办法事先知道元素只是文本(因此getElementText会抛出异常,因为不会留下元素) . 所以我决定使用过滤器,仅过滤标签元素,并以这种方式迭代抛出文档:
InputStream in = null;
try {
in = new FileInputStream("file.xml");
DatiEstratti de = DatiEstratti.getInstance();
// Processamento ad eventi
XMLInputFactory factory = (XMLInputFactory) XMLInputFactory.newInstance();
XMLEventReader eventReader = factory.createXMLEventReader(in);
// usa il filtro per filtrare solo i tag element
eventReader = factory.createFilteredReader(eventReader, new ElementOnlyFilter());
while (eventReader.hasNext()) {
XMLEvent event = eventReader.nextEvent();
if (event.getEventType() == XMLStreamConstants.START_ELEMENT) {
StartElement startElement = event.asStartElement();
XMLEvent peekEvent = eventReader.peek();
if(peekEvent.isEndElement()){
// questa è la prima volta che viene fatto un pop
// quindi è una foglia.
// recupera il dato.
String value = eventReader.getElementText();
logger.info("dato : " + value);
}
String nome = startElement.getName().getLocalPart();
String prefix = startElement.getName().getPrefix();
if (prefix != null) {
nome = prefix + ":" + nome;
}
de.push(nome);
logger.info("push : " + de.stampaPercorso());
} else if ((event.getEventType() == XMLStreamConstants.END_ELEMENT)) {
de.pop();
logger.info("pop : " + de.stampaPercorso());
if (0 > de.nLivelliPercorso()) {
break;
}
}
//handle more event types here...
}
...过滤器的位置是:
public class ElementOnlyFilter implements EventFilter, StreamFilter {
/* implementation of EventFilter interface */
@Override
public boolean accept(XMLEvent event) {
return acceptInternal(event.getEventType( ));
}
/* implementation of StreamFilter interface */
@Override
public boolean accept(XMLStreamReader reader) {
return acceptInternal(reader.getEventType( ));
}
/* internal utility method */
private boolean acceptInternal(int eventType) {
return eventType == XMLStreamConstants.START_ELEMENT
|| eventType == XMLStreamConstants.END_ELEMENT;
}
}
问题是,当发现请假时,我得到以下异常:
javax.xml.stream.XMLStreamException: ParseError at [row,col]:[3,42]
Message: parser must be on START_ELEMENT to read next text
at com.sun.xml.internal.stream.XMLEventReaderImpl.getElementText(XMLEventReaderImpl.java:114)
at javax.xml.stream.util.EventReaderDelegate.getElementText(EventReaderDelegate.java:88)
at xmlparser.XmlParser.main(XmlParser.java:63)
我不知道 . 这段代码有问题吗?我认为peek()不会改变读者,所以getElementText()应该由start元素调用 . 还有另一种方法来实现我的目标吗?
1 回答
首先,如果过滤只包含开始和结束元素事件,那么根本不会看到叶子节点中包含的文本 . 我会使用不同的方法,使用未经过滤的流,如下所示:
诀窍是结束元素部分末尾的
content = null
- 如果content
非空,则在进入if(event.isEndElement())
块时,你知道在这个和它对应的开始标记之间没有介入的结束元素事件,即它是一片叶子节点 .