public class JOCLContentHandler extends 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 Object
s
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 and Description |
---|---|
protected boolean |
_acceptEmptyNamespaceForAttributes
When
true , I will treat attributes with an
empty namespace URI as part of the JOCL namespace. |
protected boolean |
_acceptEmptyNamespaceForElements
When
true , I will treat elements with an
empty namespace URI as part of the JOCL namespace. |
protected boolean |
_acceptJoclPrefixForAttributes
When
true , I will treat attributes with the
JOCL_PREFIX but no namespace URI as being
mapped to the jocl namespace. |
protected boolean |
_acceptJoclPrefixForElements
When
true , I will treat elements with the
JOCL_PREFIX but no namespace URI as being
mapped to the jocl namespace. |
protected org.apache.tomcat.dbcp.jocl.JOCLContentHandler.ConstructorDetails |
_cur
The object I'm currently working on.
|
protected Locator |
_locator
My
Locator . |
protected ArrayList<Class<?>> |
_typeList
A list of the types (
Class es) already created via the parse. |
protected ArrayList<Object> |
_valueList
A list of the values (
Object s) already created via the parse. |
protected static String |
ATT_CLASS
The name of the "object" element's "class" attribute.
|
protected static String |
ATT_ISNULL
The name of the "object" element's "isnull" attribute.
|
protected static String |
ATT_VALUE
The name of the "value" attribute.
|
protected static String |
ELT_ARRAY
The name of the "array" element.
|
protected static String |
ELT_BOOLEAN
The name of the "boolean" element.
|
protected static String |
ELT_BYTE
The name of the "byte" element.
|
protected static String |
ELT_CHAR
The name of the "char" element.
|
protected static String |
ELT_COLLECTION
The name of the "collection" element.
|
protected static String |
ELT_DOUBLE
The name of the "double" element.
|
protected static String |
ELT_FLOAT
The name of the "float" element.
|
protected static String |
ELT_INT
The name of the "int" element.
|
protected static String |
ELT_LIST
The name of the "list" element.
|
protected static String |
ELT_LONG
The name of the "long" element.
|
protected static String |
ELT_OBJECT
The name of the "object" element.
|
protected static String |
ELT_SHORT
The name of the "short" element.
|
protected static String |
ELT_STRING
The name of the "string" element.
|
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 and 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 and Description |
---|---|
protected void |
addObject(Class<?> type,
Object val)
Add the specified object either to my type/value list, or
as an argument to the object I'm currently constructing.
|
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) |
protected String |
getAttributeValue(String localname,
Attributes attr)
Equivalent to
. |
protected String |
getAttributeValue(String localname,
Attributes attr,
String implied)
Returns the value of attribute with the given
localname within the JOCL
namespace from the given set of Attributes . |
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.
|
protected boolean |
isJoclNamespace(String uri,
String localname,
String qname)
Returns
true if the given attributes define an
element within the JOCL namespace (according to my current
configuration.) |
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(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(InputSource in)
Parses a JOCL document from the specified
InputSource , using thethe
XMLReader specified by the org.xml.sax.driver
property. |
static JOCLContentHandler |
parse(InputSource in,
XMLReader reader)
Parses a JOCL document from the specified
InputSource , using the
specified XMLReader . |
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(InputStream in,
XMLReader reader)
Parses a JOCL document from the specified
InputStream , using the specified
XMLReader . |
static JOCLContentHandler |
parse(Reader in)
|
static JOCLContentHandler |
parse(Reader in,
XMLReader reader)
|
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) |
characters, endDocument, endPrefixMapping, error, fatalError, ignorableWhitespace, notationDecl, processingInstruction, resolveEntity, skippedEntity, startDocument, startPrefixMapping, unparsedEntityDecl, warning
public static final String JOCL_NAMESPACE_URI
http://apache.org/xml/xmlns/jakarta/commons/jocl
.public static final String JOCL_PREFIX
jocl:
.protected ArrayList<Class<?>> _typeList
Class
es) already created via the parse.protected ArrayList<Object> _valueList
Object
s) already created via the parse.protected org.apache.tomcat.dbcp.jocl.JOCLContentHandler.ConstructorDetails _cur
protected boolean _acceptEmptyNamespaceForElements
true
, I will treat elements with an
empty namespace URI as part of the JOCL namespace.JOCL_NAMESPACE_URI
protected boolean _acceptJoclPrefixForElements
true
, I will treat elements with the
JOCL_PREFIX
but no namespace URI as being
mapped to the jocl namespace.JOCL_PREFIX
,
JOCL_NAMESPACE_URI
protected boolean _acceptEmptyNamespaceForAttributes
true
, I will treat attributes with an
empty namespace URI as part of the JOCL namespace.JOCL_NAMESPACE_URI
protected boolean _acceptJoclPrefixForAttributes
true
, I will treat attributes with the
JOCL_PREFIX
but no namespace URI as being
mapped to the jocl namespace.JOCL_PREFIX
,
JOCL_NAMESPACE_URI
protected static final String ELT_OBJECT
protected static final String ELT_ARRAY
protected static final String ELT_COLLECTION
protected static final String ELT_LIST
protected static final String ATT_CLASS
protected static final String ATT_ISNULL
protected static final String ELT_BOOLEAN
protected static final String ELT_BYTE
protected static final String ELT_CHAR
protected static final String ELT_DOUBLE
protected static final String ELT_FLOAT
protected static final String ELT_INT
protected static final String ELT_LONG
protected static final String ELT_SHORT
protected static final String ELT_STRING
protected static final String ATT_VALUE
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 static void main(String[] args) throws Exception
org.xml.sax.driver
system property to specify
an XMLReader
.Exception
public static JOCLContentHandler parse(File f) throws SAXException, FileNotFoundException, 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 documentSAXException
FileNotFoundException
IOException
public static JOCLContentHandler parse(Reader in) throws SAXException, 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 documentSAXException
IOException
public static JOCLContentHandler parse(InputStream in) throws SAXException, 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 documentSAXException
IOException
public static JOCLContentHandler parse(InputSource in) throws SAXException, 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 documentSAXException
IOException
public static JOCLContentHandler parse(File f, XMLReader reader) throws SAXException, FileNotFoundException, 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 documentSAXException
FileNotFoundException
IOException
public static JOCLContentHandler parse(Reader in, XMLReader reader) throws SAXException, 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 documentSAXException
IOException
public static JOCLContentHandler parse(InputStream in, XMLReader reader) throws SAXException, 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 documentSAXException
IOException
public static JOCLContentHandler parse(InputSource in, XMLReader reader) throws SAXException, 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 documentSAXException
IOException
public int size()
public void clear()
public void clear(int i)
public Class<?> getType(int i)
public Object getValue(int i)
public Object[] getValueArray()
public Object[] getTypeArray()
public void startElement(String uri, String localName, String qname, Attributes attr) throws SAXException
startElement
in interface ContentHandler
startElement
in class DefaultHandler
SAXException
public void endElement(String uri, String localName, String qname) throws SAXException
endElement
in interface ContentHandler
endElement
in class DefaultHandler
SAXException
public void setDocumentLocator(Locator locator)
setDocumentLocator
in interface ContentHandler
setDocumentLocator
in class DefaultHandler
protected boolean isJoclNamespace(String uri, String localname, String qname)
true
if the given attributes define an
element within the JOCL namespace (according to my current
configuration.)protected String getAttributeValue(String localname, Attributes attr)
getAttributeValue(localname,attr,null)
.protected String getAttributeValue(String localname, Attributes attr, String implied)
localname
within the JOCL
namespace from the given set of Attributes
.
If no such attribute can be found, returns
implied
.localname
- the unqualified name of the attribute to look forattr
- the Attributes in which to find the valueimplied
- the default value for the attributelocalname
within the JOCL
namespace from the given set of Attributes
.
If no such attribute can be found, returns
implied
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