Getting document as null [#document: null] After parsing XML in java using DocumentBuilder

问题

After parsing the documengt I am getting null, even though the document contains data. Here is my code, I have set all validations to false.

DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();

    domFactory.setNamespaceAware(false); // never forget this!
    domFactory.setCoalescing(false);
    domFactory.setValidating(false);
    domFactory.setFeature("http://xml.org/sax/features/namespaces", false);
    domFactory.setFeature("http://xml.org/sax/features/validation", false);
    domFactory.setFeature("http://apache.org/xml/features/nonvalidating/load-dtd-grammar", false);
    domFactory.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
    domFactory.setFeature("http://apache.org/xml/features/allow-java-encodings",
                       true);



    DocumentBuilder builder = domFactory.newDocumentBuilder();

    builder.setEntityResolver(new EntityResolver() {
        public InputSource resolveEntity(java.lang.String publicId, java.lang.String systemId)
                throws SAXException, java.io.IOException {
            if (publicId.equals("--myDTDpublicID--"))
                // this deactivates the open office DTD
                return new InputSource(new ByteArrayInputStream("<?xml version='1.0' encoding='UTF-8'?>".getBytes()));
            else return null;
        }
    });


    Document doc = null;
    URL url = new URL(urlStr);
    URLConnection urlc = url.openConnection();



    doc = builder.parse(urlc.getInputStream());
    System.out.println("doc:" + doc.toString());

The response comes as :

doc:[#document: null]

Why? Am I missing some validation?

回答1:

[#document: null] is just the toString of your doc instance, it doesn't output your whole XML document.

The instance itself is not null, you can probably continue your processing without a problem.

回答2:

you should add the static modifier to your Document object, I had the same problem and after the parsing action all non-static objects were simply referring to null. Making it static somehow forces java to keep the reference to the created object during the parse action in your variable.

来源：https://stackoverflow.com/questions/5694600/getting-document-as-null-document-null-after-parsing-xml-in-java-using-docum

标签

xml

null

document