com.sun.xml.bind.v2.runtime.unmarshaller

Interface XmlVisitor

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 method. For example, see Base64Data.

Error Handling

The visitor may throw SAXException to abort the unmarshalling process in the middle.
Nested Class Summary
static interfaceXmlVisitor.TextPredictor
Method Summary
voidendDocument()
voidendElement(TagName tagName)
voidendPrefixMapping(String prefix)
Called after XmlVisitor event to notify the end of a binding.
UnmarshallingContextgetContext()
Returns the UnmarshallingContext at the end of the chain.
XmlVisitor.TextPredictorgetPredictor()
Gets the predictor that can be used for the caller to avoid calling text unnecessarily.
voidstartDocument(LocatorEx locator, NamespaceContext nsContext)
Notifies a start of the document.
voidstartElement(TagName tagName)
Notifies a start tag of a new element. namespace URIs and local names must be interned.
voidstartPrefixMapping(String prefix, String nsUri)
Called before XmlVisitor event to notify a new namespace binding.
voidtext(CharSequence pcdata)
Text events.

Method Detail

endDocument

public void endDocument()

endElement

public void endElement(TagName tagName)

endPrefixMapping

public void endPrefixMapping(String prefix)
Called after XmlVisitor event to notify the end of a binding.

getContext

public UnmarshallingContext getContext()
Returns the UnmarshallingContext at the end of the chain.

Returns: always return the same object, so caching the result is recommended.

getPredictor

public XmlVisitor.TextPredictor getPredictor()
Gets the predictor that can be used for the caller to avoid calling text unnecessarily.

startDocument

public void startDocument(LocatorEx locator, NamespaceContext nsContext)
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 XmlVisitor 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.)

startElement

public void startElement(TagName tagName)
Notifies a start tag of a new element. namespace URIs and local names must be interned.

startPrefixMapping

public void startPrefixMapping(String prefix, String nsUri)
Called before XmlVisitor event to notify a new namespace binding.

text

public void text(CharSequence pcdata)
Text events.

The caller should consult 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.