public class JOCLContentHandler
extends org.xml.sax.helpers.DefaultHandler
ContentHandler
for the Java Object Configuration Language.
JOCL provides an XML syntax for constructing arbitrary Java
Object
instances. It does not define a full
XML document type (there's no root element), but rather an
XML fragment describing the 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 endElement(java.lang.String,java.lang.String,java.lang.String)
has been invoked by the XMLReader
), it will be appended to a list of Objects
maintained by the JOCLContentHandler.
(See size()
,
clear()
,
clear(int)
,
getType(int)
,
getValue(int)
,
getTypeArray()
,
and
getValueArray()
.)
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
getTypeArray()
method
will return an array composed
of two instances of java.util.Date. The sequence of
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 primitive values and arguments,
as well as for constructing 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
Object
s. The type
for these
objects will reflect the proper primitive type, however. When invoked with an
<object> parent, these will be treated as primitive arguments to the
specified Object
's constructor. For example, while:
<int value="5"/> <int value="26"/> <int value="100"/>
results in three Integer
instances being added to the
list of values, with types corresponding to Integer
, the fragment:
<int value="5"/> <int value="26"/> <int value="100"/>
results in three Integer
instances being added to the
list of values, with types corresponding to 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|array|collection|list|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 ContentHandler
s
that include JOCL as part of their grammar. Simply extend this class, and override the
startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)
,
DefaultHandler.characters(char[], int, int)
,
and endElement(java.lang.String, java.lang.String, java.lang.String)
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.
Modifier and Type | Field | Description |
---|---|---|
static java.lang.String |
JOCL_NAMESPACE_URI |
The JOCL namespace URI, http://apache.org/xml/xmlns/jakarta/commons/jocl.
|
static java.lang.String |
JOCL_PREFIX |
The default JOCL prefix, jocl:.
|
Constructor | Description |
---|---|
JOCLContentHandler() |
Equivalent to
JOCLContentHandler(true,true,true,true) . |
JOCLContentHandler(boolean emptyEltNS,
boolean joclEltPrefix,
boolean emptyAttrNS,
boolean joclAttrPrefix) |
Construct a JOCLContentHandler.
|
Modifier and Type | Method | Description |
---|---|---|
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(java.lang.String uri,
java.lang.String localName,
java.lang.String qname) |
|
java.lang.Class |
getType(int i) |
Returns the type of the object at the specified index.
|
java.lang.Object[] |
getTypeArray() |
Returns a shallow copy of my list of types.
|
java.lang.Object |
getValue(int i) |
Returns the value of the object at the specified index.
|
java.lang.Object[] |
getValueArray() |
Returns a shallow copy of my list of values.
|
static void |
main(java.lang.String[] args) |
A simple tester method.
|
static JOCLContentHandler |
parse(java.io.File f) |
Parses a JOCL document from the specified file, using the
XMLReader specified by the org.xml.sax.driver
property. |
static JOCLContentHandler |
parse(java.io.File f,
org.xml.sax.XMLReader reader) |
Parses a JOCL document from the specified file, using the
XMLReader specified by the org.xml.sax.driver
property. |
static JOCLContentHandler |
parse(java.io.InputStream in) |
Parses a JOCL document from the specified
InputStream , using the
XMLReader specified by the org.xml.sax.driver
property. |
static JOCLContentHandler |
parse(java.io.InputStream in,
org.xml.sax.XMLReader reader) |
Parses a JOCL document from the specified
InputStream , using the specified
XMLReader . |
static JOCLContentHandler |
parse(java.io.Reader in) |
Parses a JOCL document from the specified
Reader , using the
XMLReader specified by the org.xml.sax.driver
property. |
static JOCLContentHandler |
parse(java.io.Reader in,
org.xml.sax.XMLReader reader) |
Parses a JOCL document from the specified
Reader , using the specified
XMLReader . |
static JOCLContentHandler |
parse(org.xml.sax.InputSource in) |
Parses a JOCL document from the specified
InputSource , using thethe
XMLReader specified by the org.xml.sax.driver
property. |
static JOCLContentHandler |
parse(org.xml.sax.InputSource in,
org.xml.sax.XMLReader reader) |
Parses a JOCL document from the specified
InputSource , using the
specified XMLReader . |
void |
setDocumentLocator(org.xml.sax.Locator locator) |
|
int |
size() |
Returns the number of values and types in my list.
|
void |
startElement(java.lang.String uri,
java.lang.String localName,
java.lang.String qname,
org.xml.sax.Attributes attr) |
public static final java.lang.String JOCL_NAMESPACE_URI
public static final java.lang.String JOCL_PREFIX
public JOCLContentHandler()
JOCLContentHandler(true,true,true,true)
.public JOCLContentHandler(boolean emptyEltNS, boolean joclEltPrefix, boolean emptyAttrNS, boolean joclAttrPrefix)
emptyEltNS
- when true I should assume any element with an empty namespace is within the JOCL namespacejoclEltPrefix
- when true I should assume any element who's prefix is jocl: and who's namespace is empty is within the JOCL namespaceemptyAttrNS
- when true I should assume any attribute with an empty namespace is within the JOCL namespacejoclAttrPrefix
- when true I should assume any attribute who's prefix is jocl: and who's namespace is empty is within the JOCL namespacepublic void clear()
public void clear(int i)
public void endElement(java.lang.String uri, java.lang.String localName, java.lang.String qname) throws org.xml.sax.SAXException
endElement
in class org.xml.sax.helpers.DefaultHandler
org.xml.sax.SAXException
public java.lang.Class getType(int i)
public java.lang.Object[] getTypeArray()
public java.lang.Object getValue(int i)
public java.lang.Object[] getValueArray()
public static void main(java.lang.String[] args) throws java.lang.Exception
XMLReader
.java.lang.Exception
public static JOCLContentHandler parse(java.io.File f) throws org.xml.sax.SAXException, java.io.FileNotFoundException, java.io.IOException
XMLReader
specified by the org.xml.sax.driver
property.
The returned JOCLContentHandler
will contain the
list of objects described by the file.f
- a File
containing the JOCL documentJOCLContentHandler
containing the list of objects described by the JOCL documentorg.xml.sax.SAXException
java.io.FileNotFoundException
java.io.IOException
public static JOCLContentHandler parse(java.io.File f, org.xml.sax.XMLReader reader) throws org.xml.sax.SAXException, java.io.FileNotFoundException, java.io.IOException
XMLReader
specified by the org.xml.sax.driver
property.
The returned JOCLContentHandler
will contain the
list of objects described by the file.f
- a File
containing the JOCL documentreader
- the XMLReader
to use to parse the fileJOCLContentHandler
containing the list of objects described by the JOCL documentorg.xml.sax.SAXException
java.io.FileNotFoundException
java.io.IOException
public static JOCLContentHandler parse(java.io.InputStream in) throws org.xml.sax.SAXException, java.io.IOException
InputStream
, using the
XMLReader
specified by the org.xml.sax.driver
property.
The returned JOCLContentHandler
will contain the
list of objects described by the file.in
- a InputStream
containing the JOCL documentJOCLContentHandler
containing the list of objects described by the JOCL documentorg.xml.sax.SAXException
java.io.IOException
public static JOCLContentHandler parse(java.io.InputStream in, org.xml.sax.XMLReader reader) throws org.xml.sax.SAXException, java.io.IOException
InputStream
, using the specified
XMLReader
.
The returned JOCLContentHandler
will contain the
list of objects described by the file.in
- a InputStream
containing the JOCL documentreader
- the XMLReader
to use to parse the documentJOCLContentHandler
containing the list of objects described by the JOCL documentorg.xml.sax.SAXException
java.io.IOException
public static JOCLContentHandler parse(java.io.Reader in) throws org.xml.sax.SAXException, java.io.IOException
Reader
, using the
XMLReader
specified by the org.xml.sax.driver
property.
The returned JOCLContentHandler
will contain the
list of objects described by the file.in
- a Reader
containing the JOCL documentJOCLContentHandler
containing the list of objects described by the JOCL documentorg.xml.sax.SAXException
java.io.IOException
public static JOCLContentHandler parse(java.io.Reader in, org.xml.sax.XMLReader reader) throws org.xml.sax.SAXException, java.io.IOException
Reader
, using the specified
XMLReader
.
The returned JOCLContentHandler
will contain the
list of objects described by the file.in
- a Reader
containing the JOCL documentreader
- the XMLReader
to use to parse the documentJOCLContentHandler
containing the list of objects described by the JOCL documentorg.xml.sax.SAXException
java.io.IOException
public static JOCLContentHandler parse(org.xml.sax.InputSource in) throws org.xml.sax.SAXException, java.io.IOException
InputSource
, using thethe
XMLReader
specified by the org.xml.sax.driver
property.
The returned JOCLContentHandler
will contain the
list of objects described by the file.in
- a InputSource
containing the JOCL documentJOCLContentHandler
containing the list of objects described by the JOCL documentorg.xml.sax.SAXException
java.io.IOException
public static JOCLContentHandler parse(org.xml.sax.InputSource in, org.xml.sax.XMLReader reader) throws org.xml.sax.SAXException, java.io.IOException
InputSource
, using the
specified XMLReader
.
The returned JOCLContentHandler
will contain the
list of objects described by the file.in
- a InputSource
containing the JOCL documentreader
- the XMLReader
to use to parse the documentJOCLContentHandler
containing the list of objects described by the JOCL documentorg.xml.sax.SAXException
java.io.IOException
public void setDocumentLocator(org.xml.sax.Locator locator)
setDocumentLocator
in class org.xml.sax.helpers.DefaultHandler
public int size()
public void startElement(java.lang.String uri, java.lang.String localName, java.lang.String qname, org.xml.sax.Attributes attr) throws org.xml.sax.SAXException
startElement
in class org.xml.sax.helpers.DefaultHandler
org.xml.sax.SAXException
Copyright © 2001-2004 Apache Software Foundation. Documenation generated April 15 2019.