如何将XML（字符串）转换为有效文档？

Question

I have XML as a string and i want to convert it to DOM document in order to parse it using XPath, i use this code to convert one String element to DOM element:

public Element convert(String xml) throws ParserConfigurationException, SAXException, IOException{

        Element sXml =  DocumentBuilderFactory
                .newInstance()
                .newDocumentBuilder()
                .parse(new ByteArrayInputStream(xml.getBytes()))
                .getDocumentElement();


        return  sXml;

    } 

but what if i want to convert a whole XML file?? i tried casting but it didn't work as you can't convert from Element to a Document(Exception thrown):

The Exception :

Exception in thread "main" java.lang.ClassCastException: com.sun.org.apache.xerces.internal.dom.DeferredElementImpl cannot be cast to org.w3c.dom.Document

The Code :

public Document convert(String xml) throws ParserConfigurationException, SAXException, IOException{

        Element sXml =  DocumentBuilderFactory
                .newInstance()
                .newDocumentBuilder()
                .parse(new ByteArrayInputStream(xml.getBytes()))
                .getDocumentElement();


        return (Document) sXml;

    } 

i also tried this but didn't work:

public Document convert(String xml) throws ParserConfigurationException, SAXException, IOException{

        Document sXml =  DocumentBuilderFactory
                .newInstance()
                .newDocumentBuilder()
                .parse(new ByteArrayInputStream(xml.getBytes()));


        return  sXml;

    } 

what can i do to fix this problem? and if there is a way in XPath to parse a String rather than a document it also will be fine.

Answer 1

Maybe by using this

public static Document stringToDocument(final String xmlSource)   
    throws SAXException, ParserConfigurationException, IOException {  
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();  
    DocumentBuilder builder = factory.newDocumentBuilder();  

    return builder.parse(new InputSource(new StringReader(xmlSource)));  
}