将文档获取为null [#document：null]使用DocumentBuilder在Java中解析XML之后

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());

doc:[#document: null]