redstone.xmlrpc
Class XmlRpcParser

java.lang.Object
  org.xml.sax.helpers.DefaultHandler
      redstone.xmlrpc.XmlRpcParser

All Implemented Interfaces:

org.xml.sax.ContentHandler, org.xml.sax.DTDHandler, org.xml.sax.EntityResolver, org.xml.sax.ErrorHandler

Direct Known Subclasses:

XmlRpcClient, XmlRpcDispatcher

public abstract class XmlRpcParser
extends org.xml.sax.helpers.DefaultHandler

An XmlRpcParser converts inbound XML-RPC messages to their Java counterparts through the use of a SAX compliant parser. This is an abstract class that is only concerned with the XML-RPC values contained in a message. Deriving classes supply a handleParsedValue() method that is called whenever an XML-RPC value has been parsed.

If a class needs to be notified of additional parts of an XML-RPC message, the startElement() or endElement() methods are overridden and extended with checks for the appropriate element. This is the case with XmlRpcClient that wants to know if a fault element is present. Also, the XmlRpcServer wants to know the name of the method for which values are supplied.

Internally, the implementation uses pre-calculated hash values of the element names to allow for switch() constructs when comparing elements supplied by the SAX parser.

Author:

Greger Olsson

Field Summary

static int	ARRAY The hash value of array elements
static int	BASE64 The hash value of double elements
static int	BOOLEAN The hash value of boolean elements
static int	DATE The hash value of double elements
static int	DOUBLE The hash value of double elements
static int	I4 The hash value of i4 elements
static int	INT The hash value of int elements
static int	MEMBER The hash value of member elements
static int	NAME The hash value of name elements
static int	STRING The hash value of string elements
static int	STRUCT The hash value of struct elements
static int	VALUE The hash value of value elements

Constructor Summary

XmlRpcParser()

Method Summary

void	characters(char[] data, int start, int length) Called by the SAX driver when character data is available.
void	endElement(java.lang.String uri, java.lang.String name, java.lang.String qualifiedName) Called by SAX driver when a new end-element has been found in the message.
void	parse(java.io.InputStream is) Parses the XML-RPC message contained in the supplied input stream.
void	startElement(java.lang.String uri, java.lang.String name, java.lang.String qualifiedName, org.xml.sax.Attributes attributes) Called by SAX driver when a new element has been found in the message.

Methods inherited from class org.xml.sax.helpers.DefaultHandler

endDocument, endPrefixMapping, error, fatalError, ignorableWhitespace, notationDecl, processingInstruction, resolveEntity, setDocumentLocator, skippedEntity, startDocument, startPrefixMapping, unparsedEntityDecl, warning

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

VALUE

public static final int VALUE

The hash value of value elements

See Also:

Constant Field Values

STRING

public static final int STRING

The hash value of string elements

See Also:

Constant Field Values

I4

public static final int I4

The hash value of i4 elements

See Also:

Constant Field Values

INT

public static final int INT

The hash value of int elements

See Also:

Constant Field Values

BOOLEAN

public static final int BOOLEAN

The hash value of boolean elements

See Also:

Constant Field Values

DOUBLE

public static final int DOUBLE

The hash value of double elements

See Also:

Constant Field Values

DATE

public static final int DATE

The hash value of double elements

See Also:

Constant Field Values

BASE64

public static final int BASE64

The hash value of double elements

See Also:

Constant Field Values

STRUCT

public static final int STRUCT

The hash value of struct elements

See Also:

Constant Field Values

ARRAY

public static final int ARRAY

The hash value of array elements

See Also:

Constant Field Values

MEMBER

public static final int MEMBER

The hash value of member elements

See Also:

Constant Field Values

NAME

public static final int NAME

The hash value of name elements

See Also:

Constant Field Values

Constructor Detail

XmlRpcParser

public XmlRpcParser()

Method Detail

parse

public void parse(java.io.InputStream is)
           throws XmlRpcException

Parses the XML-RPC message contained in the supplied input stream. It does so by using the current SAX driver, and will call handleParsedValue() for every top-level value contained in the message. This method can be overridden to supply additional processing, like identifying method names and such. This implementation is only concerned with the values of the message.

Parameters:

is - The input stream containing the XML-RPC message

Throws:

XmlRpcException

startElement

public void startElement(java.lang.String uri,
                         java.lang.String name,
                         java.lang.String qualifiedName,
                         org.xml.sax.Attributes attributes)
                  throws org.xml.sax.SAXException

Called by SAX driver when a new element has been found in the message.

This implementation uses a switch construct on the hash value of the element name. This increases readability, in my opinion, and perhaps performance as well (only one loop -- in hashCode() -- instead of in every equals() call).

Specified by:

startElement in interface org.xml.sax.ContentHandler

Overrides:

startElement in class org.xml.sax.helpers.DefaultHandler

Parameters:

See - SAX documentation

Throws:

org.xml.sax.SAXException

endElement

public void endElement(java.lang.String uri,
                       java.lang.String name,
                       java.lang.String qualifiedName)
                throws org.xml.sax.SAXException

Called by SAX driver when a new end-element has been found in the message.

This implementation determines if our current state is that we have a current value that needs to be processed, and if that value has some character data in the buffer required to finalize the value. The handleParsedValue() method is only called if a top-level value element has ended. If not, the value is added to the enclosing value, which may be an array or a struct.

Note that struct values are processed when the member element ends and not when the value element ends. This is because we need to use the included member name.

Specified by:

endElement in interface org.xml.sax.ContentHandler

Overrides:

endElement in class org.xml.sax.helpers.DefaultHandler

Parameters:

See - SAX documentation

Throws:

org.xml.sax.SAXException

characters

public void characters(char[] data,
                       int start,
                       int length)

Called by the SAX driver when character data is available.

This implementation appends the data to an internal string buffer. The method is called for every element, wether characters are included int the element or not. This leads to the buffer being prepended with whitespace until actual character data is aquired. This is removed using the trim() method when the character data is consumed.

Specified by:

characters in interface org.xml.sax.ContentHandler

Overrides:

characters in class org.xml.sax.helpers.DefaultHandler

Parameters:

See - SAX documentation