org.apache.commons.jocl
public class JOCLContentHandler extends DefaultHandler
JOCL provides an XML syntax for constructing arbitrary Java
java.lang.Object instances. It does not define a full
XML document type (there's no root element), but rather an
XML fragment describing the java.lang.Object Objects
to be
constructed.
In a JOCL fragment, one may define a series of objects using the object element. A trivial example is:
<object class="java.util.Date"/>which constructs an instance of java.util.Date using the no-argument constructor.
After a "root-level" <object> element has been processed (that is, once JOCLContentHandler has been invoked by the XMLReader), it will be appended to a list of Objects maintained by the JOCLContentHandler.
(See JOCLContentHandler, JOCLContentHandler, JOCLContentHandler, JOCLContentHandler, JOCLContentHandler, JOCLContentHandler, and JOCLContentHandler.)
You can list multiple object elements in a fragment. For example, after processing the JOCL fragment:
<object class="java.util.Date"/> <object class="java.util.Date"/>The JOCLContentHandler method will return an composed of two instances of java.util.Date. The sequence of
java.lang.Object Objects
in the array
will correspond to the sequence of <object> elements in the JOCL fragment.
As we've seen, when used with no child-elements, the <object> tag will cause the no-argument constructor of the specified class to be invoked. It is also possible to nest <object> tags to provide arguments for the constructor. For example, the fragment:
<object class="mypackage.Foo"> <object class="mypackage.Bar"/> </object>will add an instance of mypackage.Foo to the object list, constructed via new mypackage.Foo(new mypackage.Bar()).
There is a special syntax available creating primative values and arguments,
as well as for constructing java.lang.String String
s. Some examples:
<byte value="3"/> <boolean value="false"/> <char value="c"/> <double value="3.14159"/> <float value="3.14"/> <int value="17"/> <long value="1700000"/> <short value="1"/> <string value="The quick brown fox..."/>
When invoked at the "root" level (that is, with no <object> parent),
this will cause the corresponding "object wrapper" to be added to the list of
java.lang.Object Object
s. The type
for these
objects will reflect the proper primative type, however. When invoked with an
<object> parent, these will be treated as primitive arguments to the
specified java.lang.Object Object
's constructor. For example, while:
<int value="5"/> <int value="26"/> <int value="100"/>
results in three java.lang.Integer instances being added to the list of values, with types corresponding to java.lang.Integer, the fragment:
<int value="5"/> <int value="26"/> <int value="100"/>
results in three java.lang.Integer instances being added to the list of values, with types corresponding to java.lang.Integer#TYPE.
Hence if you want to invoke the mypackage.Foo(java.lang.Integer,java.lang.Integer,java.lang.Integer) constructor, use:
<object class="mypackage.Foo"/> <object class="java.lang.Integer"><int value="5"/></object> <object class="java.lang.Integer"><int value="26"/></object> <object class="java.lang.Integer"><int value="100"/></object> </object>
If you want to invoke the mypackage.Foo(int,int,int) constructor, use:
<object class="mypackage.Foo"/> <int value="5"/> <int value="26"/> <int value="100"/> </object>
If you'd like to creat a null object, use:
<object class="mypackage.Bar" null="true"/>
Here's a simple but complete example:
<?xml version="1.0"?> <arbitrary-root xmlns="http://apache.org/xml/xmlns/jakarta/commons/jocl"> <string value="Hello World!"/> <string/> <boolean/> <boolean value="true"/> <byte value="1"/> <short value="1"/> <int value="1"/> <long value="1"/> <float value="1.0"/> <double value="1.0"/> <object class="java.util.Date"/> <object class="java.util.Date"> <int value="1"/> <int value="1"/> <int value="1"/> </object> </arbitrary-root>
Formally, a DTD for the JOCL grammar is as follows:
<!ELEMENT object (object|byte|boolean|char|double|float|int|long|short|string)*> <!ATTLIST object class CDATA #REQUIRED null (true|false) "false"> <!ELEMENT byte EMPTY> <!ATTLIST byte value CDATA #REQUIRED> <!ELEMENT boolean EMPTY> <!ATTLIST boolean value (true|false) #REQUIRED> <!ELEMENT char EMPTY> <!ATTLIST char value CDATA #REQUIRED> <!ELEMENT double EMPTY> <!ATTLIST double value CDATA #REQUIRED> <!ELEMENT float EMPTY> <!ATTLIST float value CDATA #REQUIRED> <!ELEMENT int EMPTY> <!ATTLIST int value CDATA #REQUIRED> <!ELEMENT long EMPTY> <!ATTLIST long value CDATA #REQUIRED> <!ELEMENT short EMPTY> <!ATTLIST short value CDATA #REQUIRED> <!ELEMENT string EMPTY> <!ATTLIST string value CDATA #REQUIRED>
This class can also be used as a base class for org.xml.sax.ContentHandlers that include JOCL as part of their grammar. Simply extend this class, and override the JOCLContentHandler, JOCLContentHandler, and JOCLContentHandler methods to handle your tags, and invoke the method of the parent class (i.e., super.XXX for elements and data that you don't handle.
A number of static methods are available for simply reading a list of objects from a InputStream, Reader or InputSource.
Note that this class is not synchronized.
Version: $Revision: 491655 $ $Date: 2007-01-01 15:05:30 -0700 (Mon, 01 Jan 2007) $
Field Summary | |
---|---|
static String | JOCL_NAMESPACE_URI
The JOCL namespace URI, http://apache.org/xml/xmlns/jakarta/commons/jocl. |
static String | JOCL_PREFIX
The default JOCL prefix, jocl:. |
Constructor Summary | |
---|---|
JOCLContentHandler()
Equivalent to JOCLContentHandler(true,true,true,true) . | |
JOCLContentHandler(boolean emptyEltNS, boolean joclEltPrefix, boolean emptyAttrNS, boolean joclAttrPrefix)
Construct a JOCLContentHandler. |
Method Summary | |
---|---|
void | clear()
Clears all the values and types in my list. |
void | clear(int i)
Removes the value/type pair at the specified index. |
void | endElement(String uri, String localName, String qname) |
Class | getType(int i)
Returns the type of the object at the specified index. |
Object[] | getTypeArray()
Returns a shallow copy of my list of types. |
Object | getValue(int i)
Returns the value of the object at the specified index. |
Object[] | getValueArray()
Returns a shallow copy of my list of values. |
static void | main(String[] args)
A simple tester method. |
static JOCLContentHandler | parse(File f)
Parses a JOCL document from the specified file, using the
XMLReader specified by the org.xml.sax.driver
property.
|
static JOCLContentHandler | parse(Reader in)
Parses a JOCL document from the specified Reader, using the
XMLReader specified by the org.xml.sax.driver
property.
|
static JOCLContentHandler | parse(InputStream in)
Parses a JOCL document from the specified InputStream, using the
XMLReader specified by the org.xml.sax.driver
property.
|
static JOCLContentHandler | parse(InputSource in)
Parses a JOCL document from the specified InputSource, using thethe
XMLReader specified by the org.xml.sax.driver
property.
|
static JOCLContentHandler | parse(File f, XMLReader reader)
Parses a JOCL document from the specified file, using the
XMLReader specified by the org.xml.sax.driver
property.
|
static JOCLContentHandler | parse(Reader in, XMLReader reader)
Parses a JOCL document from the specified Reader, using the specified
XMLReader.
|
static JOCLContentHandler | parse(InputStream in, XMLReader reader)
Parses a JOCL document from the specified InputStream, using the specified
XMLReader.
|
static JOCLContentHandler | parse(InputSource in, XMLReader reader)
Parses a JOCL document from the specified InputSource, using the
specified XMLReader.
|
void | setDocumentLocator(Locator locator) |
int | size()
Returns the number of values and types in my list. |
void | startElement(String uri, String localName, String qname, Attributes attr) |
JOCLContentHandler(true,true,true,true)
.Parameters: emptyEltNS when true I should assume any element with an empty namespace is within the JOCL namespace joclEltPrefix when true I should assume any element who's prefix is jocl: and who's namespace is empty is within the JOCL namespace emptyAttrNS when true I should assume any attribute with an empty namespace is within the JOCL namespace joclAttrPrefix when true I should assume any attribute who's prefix is jocl: and who's namespace is empty is within the JOCL namespace
Parameters: f a File containing the JOCL document
Returns: a JOCLContentHandler containing the list of objects described by the JOCL document
Parameters: in a Reader containing the JOCL document
Returns: a JOCLContentHandler containing the list of objects described by the JOCL document
Parameters: in a InputStream containing the JOCL document
Returns: a JOCLContentHandler containing the list of objects described by the JOCL document
Parameters: in a InputSource containing the JOCL document
Returns: a JOCLContentHandler containing the list of objects described by the JOCL document
Parameters: f a File containing the JOCL document reader the XMLReader to use to parse the file
Returns: a JOCLContentHandler containing the list of objects described by the JOCL document
Parameters: in a Reader containing the JOCL document reader the XMLReader to use to parse the document
Returns: a JOCLContentHandler containing the list of objects described by the JOCL document
Parameters: in a InputStream containing the JOCL document reader the XMLReader to use to parse the document
Returns: a JOCLContentHandler containing the list of objects described by the JOCL document
Parameters: in a InputSource containing the JOCL document reader the XMLReader to use to parse the document
Returns: a JOCLContentHandler containing the list of objects described by the JOCL document
Returns: the number of values and types in my list.