Interface XmlVisitor

  • All Known Implementing Classes:
    InterningXmlVisitor, UnmarshallingContext

    public interface XmlVisitor
    Walks the XML document structure. Implemented by the unmarshaller and called by the API-specific connectors.

    Event Call Sequence

    The XmlVisitor expects the event callbacks in the following order:
     CALL SEQUENCE := startDocument ELEMENT endDocument
     ELEMENT       := startPrefixMapping ELEMENT endPrefixMapping
                   |  startElement BODY endElement
     BODY          := text? (ELEMENT text?)*
     
    Note in particular that text events may not be called in a row; consecutive characters (even those separated by PIs and comments) must be reported as one event, unlike SAX.

    All namespace URIs, local names, and prefixes of element and attribute names must be interned. qnames need not be interned.

    Typed PCDATA

    For efficiency, JAXB RI defines a few CharSequence implementations that can be used as a parameter to the text(CharSequence) method. For example, see Base64Data.

    Error Handling

    The visitor may throw SAXException to abort the unmarshalling process in the middle.
    Author:
    Kohsuke Kawaguchi
    • Method Detail

      • startDocument

        void startDocument​(LocatorEx locator,
                           javax.xml.namespace.NamespaceContext nsContext)
                    throws org.xml.sax.SAXException
        Notifies a start of the document.
        Parameters:
        locator - This live object returns the location information as the parsing progresses. must not be null.
        nsContext - Some broken XML APIs can't iterate all the in-scope namespace bindings, which makes it impossible to emulate startPrefixMapping(String, String) correctly when unmarshalling a subtree. Connectors that use such an API can pass in additional NamespaceContext object that knows about the in-scope namespace bindings. Otherwise (and normally) it is null.

        Ideally this object should be immutable and only represent the namespace URI bindings in the context (those done above the element that JAXB started unmarshalling), but it can also work even if it changes as the parsing progress (to include namespaces declared on the current element being parsed.)

        Throws:
        org.xml.sax.SAXException
      • endDocument

        void endDocument()
                  throws org.xml.sax.SAXException
        Throws:
        org.xml.sax.SAXException
      • startElement

        void startElement​(TagName tagName)
                   throws org.xml.sax.SAXException
        Notifies a start tag of a new element. namespace URIs and local names must be interned.
        Throws:
        org.xml.sax.SAXException
      • endElement

        void endElement​(TagName tagName)
                 throws org.xml.sax.SAXException
        Throws:
        org.xml.sax.SAXException
      • text

        void text​(java.lang.CharSequence pcdata)
           throws org.xml.sax.SAXException
        Text events.

        The caller should consult XmlVisitor.TextPredictor to see if the unmarshaller is expecting any PCDATA. If the above is returning false, the caller is OK to skip any text in XML. The net effect is that we can ignore whitespaces quickly.

        Parameters:
        pcdata - represents character data. This object can be mutable (such as StringBuilder); it only needs to be fixed while this method is executing.
        Throws:
        org.xml.sax.SAXException