Java Reference
In-Depth Information
return new InputSource("recipeml.dtd") else return null;
statementwouldsuffice),I'vechosentouseamapincaseIwanttoexpandthenumber
of mappings in the future. In another scenario, you would probably find a map to be
very convenient. For example, it's easier to use a map than to use a series of if state-
mentsinacustomentityresolverthatmapsXHTML'sstrict,transitional,andframeset
formal public identifiers, andalso maps its various entity sets tolocal copies ofthese
document files.
Theoverriding
resolveEntity()
methoduses
publicId
'sargumenttolocate
thecorrespondingsystemidentifierinthemap—the
systemId
parametervalueisig-
noredbecauseitneverreferstothelocalcopyof
recipeml.dtd
.Whenthemapping
isfound,an
InputSource
objectiscreatedandreturned.Ifthemappingcouldnotbe
found, the null reference would be returned.
To install this custom entity resolver in
SAXDemo
, specify
xm-
lr.setEntityResolver(new LocalRecipeML());
prior to the
parse()
methodcall.Afterrecompilingthesourcecode,execute
java SAXDemo gcs.xml
,
the message “
obtaining
recipeml.dtd
” prior to the call to
cached
startEntity()
.
Tip
TheSAXAPIincludesan
org.xml.sax.ext.EntityResolver2
inter-
face that provides improved supportforresolving entities. Ifyouprefer toimplement
EntityResolver2
instead of
EntityResolver
, you must replace the
setEntityResolver()
calltoinstalltheentityresolverwitha
setFeature()
tp://xml.org/sax/features/
prefix).
Parsing and Creating XML Documents with DOM
Document Object Model (DOM)
is an API for parsing an XML document into an in-
memorytreeofnodes,andforcreatinganXMLdocumentfromatreeofnodes.Aftera
DOMparserhascreatedadocumenttree,anapplicationusestheDOMAPItonavigate
over and extract infoset items from the tree's nodes.
Note
DOM originated as an object model for the Netscape Navigator 3 and Mi-
crosoft Internet Explorer 3 web browsers. Collectively, these implementations are
known as DOM Level 0. Because each vendor's DOM implementation was only
