修改后无法写回XML

Question

I am reading a XML and changing some attributes. Then I am writing it back to file as XML and it returns me a blank file. If I don't modify the node it works fine. What I am doing wrong, please advice.

DocumentBuilderFactory dbFactory = DocumentBuilderFactory
                        .newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(origDrXML);
doc.getDocumentElement().normalize();
NodeList nodes = doc.getElementsByTagName("log");
for (int i = 0; i < nodes.getLength(); i++) {
    NodeList children = nodes.item(i).getChildNodes();
int len = children.getLength();
for (int j = 0; j <= children.getLength(); j++) {
    if (children.item(j).getNodeName().equalsIgnoreCase("directory"))
        children.item(j).setTextContent("D:\\Logs");
    }
 } // End of Childrens of <log>
} // End of <log> Tag */
Transformer transformer = TransformerFactory.newInstance().newTransformer();
StreamResult result = new StreamResult(new StringWriter());
DOMSource source = new DOMSource(doc);
transformer.transform(source, result);
String xmlString = result.getWriter().toString();
System.out.println(xmlString);

Answer 1

Can you try with a null check?

for (int j = 0; j <= children.getLength(); j++) {
    if(children.item(j) != null ) {
            if (children.item(j).getNodeName().equalsIgnoreCase("directory"))
                    children.item(j).setTextContent("D:\\Logs");
    }
}

This works for me!

Answer 2

您是否曾在调用writer.flush()之前尝试调用writer.toString() ？

Answer 3

You could try using the DOM LSSerializer mechanism instead of a Transformer . Replace all this:

Transformer transformer = TransformerFactory.newInstance().newTransformer();
StreamResult result = new StreamResult(new StringWriter());
DOMSource source = new DOMSource(doc);
transformer.transform(source, result);
String xmlString = result.getWriter().toString();

with this

LSSerializer ser =
    ((DOMImplementationLS)doc.getImplementation()).createLSSerializer();
String xmlString = ser.writeToString(doc);