Class JOCLContentHandler
- java.lang.Object
-
- org.xml.sax.helpers.DefaultHandler
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- org.apache.commons.jocl.JOCLContentHandler
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- All Implemented Interfaces:
org.xml.sax.ContentHandler
,org.xml.sax.DTDHandler
,org.xml.sax.EntityResolver
,org.xml.sax.ErrorHandler
public class JOCLContentHandler extends org.xml.sax.helpers.DefaultHandler
AContentHandler
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 theObjects
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 theXMLReader
), it will be appended to a list of Objects maintained by the JOCLContentHandler.(See
size()
,clear()
,clear(int)
,getType(int)
,getValue(int)
,getTypeArray()
, andgetValueArray()
.)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"/>
ThegetTypeArray()
method will return an array composed of two instances of java.util.Date. The sequence ofObjects
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. Thetype
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 specifiedObject
'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 toInteger
, 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 toInteger.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 thestartElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)
,DefaultHandler.characters(char[], int, int)
, andendElement(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
orInputSource
.Note that this class is not synchronized.
- Version:
- $Revision: 883416 $ $Date: 2009-11-23 12:12:14 -0500 (Mon, 23 Nov 2009) $
- Author:
- Rodney Waldhoff
-
-
Field Summary
Fields 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:.
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Constructor Summary
Constructors Constructor Description JOCLContentHandler()
Equivalent toJOCLContentHandler(true,true,true,true)
.JOCLContentHandler(boolean emptyEltNS, boolean joclEltPrefix, boolean emptyAttrNS, boolean joclAttrPrefix)
Construct a JOCLContentHandler.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods 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 theXMLReader
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 theXMLReader
specified by the org.xml.sax.driver property.static JOCLContentHandler
parse(java.io.InputStream in)
Parses a JOCL document from the specifiedInputStream
, using theXMLReader
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 specifiedInputStream
, using the specifiedXMLReader
.static JOCLContentHandler
parse(java.io.Reader in)
Parses a JOCL document from the specifiedReader
, using theXMLReader
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 specifiedReader
, using the specifiedXMLReader
.static JOCLContentHandler
parse(org.xml.sax.InputSource in)
Parses a JOCL document from the specifiedInputSource
, using thetheXMLReader
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 specifiedInputSource
, using the specifiedXMLReader
.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)
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-
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Field Detail
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JOCL_NAMESPACE_URI
public static final java.lang.String JOCL_NAMESPACE_URI
The JOCL namespace URI, http://apache.org/xml/xmlns/jakarta/commons/jocl.- See Also:
- Constant Field Values
-
JOCL_PREFIX
public static final java.lang.String JOCL_PREFIX
The default JOCL prefix, jocl:.- See Also:
- Constant Field Values
-
-
Constructor Detail
-
JOCLContentHandler
public JOCLContentHandler()
Equivalent toJOCLContentHandler(true,true,true,true)
.
-
JOCLContentHandler
public JOCLContentHandler(boolean emptyEltNS, boolean joclEltPrefix, boolean emptyAttrNS, boolean joclAttrPrefix)
Construct a JOCLContentHandler.- Parameters:
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 namespace
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Method Detail
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main
public static void main(java.lang.String[] args) throws java.lang.Exception
A simple tester method. Reads a JOCL document from standard in and prints a list of the objects created to standard out. (Use the org.xml.sax.driver system property to specify anXMLReader
.- Throws:
java.lang.Exception
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parse
public static JOCLContentHandler parse(java.io.File f) throws org.xml.sax.SAXException, java.io.FileNotFoundException, java.io.IOException
Parses a JOCL document from the specified file, using theXMLReader
specified by the org.xml.sax.driver property. The returnedJOCLContentHandler
will contain the list of objects described by the file.- Parameters:
f
- aFile
containing the JOCL document- Returns:
- a
JOCLContentHandler
containing the list of objects described by the JOCL document - Throws:
org.xml.sax.SAXException
java.io.FileNotFoundException
java.io.IOException
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parse
public static JOCLContentHandler parse(java.io.Reader in) throws org.xml.sax.SAXException, java.io.IOException
Parses a JOCL document from the specifiedReader
, using theXMLReader
specified by the org.xml.sax.driver property. The returnedJOCLContentHandler
will contain the list of objects described by the file.- Parameters:
in
- aReader
containing the JOCL document- Returns:
- a
JOCLContentHandler
containing the list of objects described by the JOCL document - Throws:
org.xml.sax.SAXException
java.io.IOException
-
parse
public static JOCLContentHandler parse(java.io.InputStream in) throws org.xml.sax.SAXException, java.io.IOException
Parses a JOCL document from the specifiedInputStream
, using theXMLReader
specified by the org.xml.sax.driver property. The returnedJOCLContentHandler
will contain the list of objects described by the file.- Parameters:
in
- aInputStream
containing the JOCL document- Returns:
- a
JOCLContentHandler
containing the list of objects described by the JOCL document - Throws:
org.xml.sax.SAXException
java.io.IOException
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parse
public static JOCLContentHandler parse(org.xml.sax.InputSource in) throws org.xml.sax.SAXException, java.io.IOException
Parses a JOCL document from the specifiedInputSource
, using thetheXMLReader
specified by the org.xml.sax.driver property. The returnedJOCLContentHandler
will contain the list of objects described by the file.- Parameters:
in
- aInputSource
containing the JOCL document- Returns:
- a
JOCLContentHandler
containing the list of objects described by the JOCL document - Throws:
org.xml.sax.SAXException
java.io.IOException
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parse
public static JOCLContentHandler parse(java.io.File f, org.xml.sax.XMLReader reader) throws org.xml.sax.SAXException, java.io.FileNotFoundException, java.io.IOException
Parses a JOCL document from the specified file, using theXMLReader
specified by the org.xml.sax.driver property. The returnedJOCLContentHandler
will contain the list of objects described by the file.- Parameters:
f
- aFile
containing the JOCL documentreader
- theXMLReader
to use to parse the file- Returns:
- a
JOCLContentHandler
containing the list of objects described by the JOCL document - Throws:
org.xml.sax.SAXException
java.io.FileNotFoundException
java.io.IOException
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parse
public static JOCLContentHandler parse(java.io.Reader in, org.xml.sax.XMLReader reader) throws org.xml.sax.SAXException, java.io.IOException
Parses a JOCL document from the specifiedReader
, using the specifiedXMLReader
. The returnedJOCLContentHandler
will contain the list of objects described by the file.- Parameters:
in
- aReader
containing the JOCL documentreader
- theXMLReader
to use to parse the document- Returns:
- a
JOCLContentHandler
containing the list of objects described by the JOCL document - Throws:
org.xml.sax.SAXException
java.io.IOException
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parse
public static JOCLContentHandler parse(java.io.InputStream in, org.xml.sax.XMLReader reader) throws org.xml.sax.SAXException, java.io.IOException
Parses a JOCL document from the specifiedInputStream
, using the specifiedXMLReader
. The returnedJOCLContentHandler
will contain the list of objects described by the file.- Parameters:
in
- aInputStream
containing the JOCL documentreader
- theXMLReader
to use to parse the document- Returns:
- a
JOCLContentHandler
containing the list of objects described by the JOCL document - Throws:
org.xml.sax.SAXException
java.io.IOException
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parse
public static JOCLContentHandler parse(org.xml.sax.InputSource in, org.xml.sax.XMLReader reader) throws org.xml.sax.SAXException, java.io.IOException
Parses a JOCL document from the specifiedInputSource
, using the specifiedXMLReader
. The returnedJOCLContentHandler
will contain the list of objects described by the file.- Parameters:
in
- aInputSource
containing the JOCL documentreader
- theXMLReader
to use to parse the document- Returns:
- a
JOCLContentHandler
containing the list of objects described by the JOCL document - Throws:
org.xml.sax.SAXException
java.io.IOException
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size
public int size()
Returns the number of values and types in my list.- Returns:
- the number of values and types in my list.
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clear
public void clear()
Clears all the values and types in my list.
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clear
public void clear(int i)
Removes the value/type pair at the specified index.
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getType
public java.lang.Class getType(int i)
Returns the type of the object at the specified index.
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getValue
public java.lang.Object getValue(int i)
Returns the value of the object at the specified index.
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getValueArray
public java.lang.Object[] getValueArray()
Returns a shallow copy of my list of values.
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getTypeArray
public java.lang.Object[] getTypeArray()
Returns a shallow copy of my list of types.
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startElement
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
- Specified by:
startElement
in interfaceorg.xml.sax.ContentHandler
- Overrides:
startElement
in classorg.xml.sax.helpers.DefaultHandler
- Throws:
org.xml.sax.SAXException
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endElement
public void endElement(java.lang.String uri, java.lang.String localName, java.lang.String qname) throws org.xml.sax.SAXException
- Specified by:
endElement
in interfaceorg.xml.sax.ContentHandler
- Overrides:
endElement
in classorg.xml.sax.helpers.DefaultHandler
- Throws:
org.xml.sax.SAXException
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setDocumentLocator
public void setDocumentLocator(org.xml.sax.Locator locator)
- Specified by:
setDocumentLocator
in interfaceorg.xml.sax.ContentHandler
- Overrides:
setDocumentLocator
in classorg.xml.sax.helpers.DefaultHandler
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