unknown host exception while parsing an xml file

Question

when i am trying to parse an xml, i am getting following exception :-

java.net.UnknownHostException: hibernate.sourceforge.net
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at sun.net.NetworkClient.doConnect(Unknown Source)
    at sun.net.www.http.HttpClient.openServer(Unknown Source)
    at sun.net.www.http.HttpClient.openServer(Unknown Source)
    at sun.net.www.http.HttpClient.<init>(Unknown Source)
    at sun.net.www.http.HttpClient.New(Unknown Source)
    at sun.net.www.http.HttpClient.New(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
    at org.apache.xerces.impl.XMLEntityManager.setupCurrentEntity(Unknown Source)
    at org.apache.xerces.impl.XMLEntityManager.startEntity(Unknown Source)
    at org.apache.xerces.impl.XMLEntityManager.startDTDEntity(Unknown Source)
    at org.apache.xerces.impl.XMLDTDScannerImpl.setInputSource(Unknown Source)
    at org.apache.xerces.impl.XMLDocumentScannerImpl$DTDDispatcher.dispatch(Unknown Source)
    at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
    at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
    at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
    at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
    at org.apache.xerces.parsers.DOMParser.parse(Unknown Source)
    at org.apache.xerces.jaxp.DocumentBuilderImpl.parse(Unknown Source)
    at javax.xml.parsers.DocumentBuilder.parse(Unknown Source)

The code that i am using to parse the xml is below:-

File hbmFile = new File(hbmFileName);
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(hbmFile);

i am trying to parse the xml that has been written for hibernate, actually it is a hibernate mapping file.

The xml that i am trying to parse is below:-

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="org.hibernate.entity.Student" table="table_student">
        <id name="rollNo" column="rool_no" type="int"/>
        <property name="name" column="st_name" type="string"/>
        <set name="marks" table="table_marks">
            <key column="roll_no"/>
            <composite-element class="org.hibernate.entity.StudentMarks">
                <property name="subject" column="st_sub"/>
                <property name="marks" column="st_marks"/>
            </composite-element>
        </set>
    </class>
</hibernate-mapping>

Please help.

Answer 1

The parser is trying to download the DTD from hibernate.sourceforge.net in order to validate the parsed XML.

However, the DNS client on the machine can't resolve that host name for some reason (it resolves fine to 82.98.86.175 on my machine).

To avoid this problem, you have to tell the DocumentBuilderFactory to ignore the DTD:

File hbmFile = new File(hbmFileName);
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

dbf.setValidating(false);
dbf.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);

DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(hbmFile);

See Make DocumentBuilder.parse ignore DTD references.

Answer 2

i used the following code and this is working fine for me..

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();  
dbf.setValidating(false);
DocumentBuilder db = dbf.newDocumentBuilder();
db.setEntityResolver(new EntityResolver() {
  @Override
  public InputSource resolveEntity(String arg0, String arg1)
        throws SAXException, IOException {
    if(arg0.contains("Hibernate")) {
        return new InputSource(new StringReader(""));
    } else {
        // TODO Auto-generated method stub
        return null;
    }
  }
});
Document doc = db.parse(hbmFile);