Package net.sf.saxon.event

Class CheckSumFilter

java.lang.Object

net.sf.saxon.event.SequenceReceiver

net.sf.saxon.event.ProxyReceiver

net.sf.saxon.event.CheckSumFilter

All Implemented Interfaces:

Result, Receiver

public class CheckSumFilter
extends ProxyReceiver

A filter to go on a Receiver pipeline and calculate a checksum of the data passing through the pipeline. Optionally the filter will also check any checksum (represented by a processing instruction with name SIGMA) found in the file.

The checksum takes account of element, attribute, and text nodes only. The order of attributes within an element makes no difference.

For the SIGMA2 checksum, the order of attributes within an element does make a difference.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	SIGMA
static final String	SIGMA2

Fields inherited from class net.sf.saxon.event.ProxyReceiver

nextReceiver

Fields inherited from class net.sf.saxon.event.SequenceReceiver

pipelineConfiguration, previousAtomic, systemId

Fields inherited from interface javax.xml.transform.Result

PI_DISABLE_OUTPUT_ESCAPING, PI_ENABLE_OUTPUT_ESCAPING

Constructor Summary

Constructors

Constructor	Description
CheckSumFilter(Receiver nextReceiver)

Method Summary

Modifier and Type	Method	Description
void	append(Item item, Location locationId, int copyNamespaces)	Append an arbitrary item (node or atomic value) to the output
void	characters(UnicodeString chars, Location locationId, int properties)	Character data
void	endDocument()	Notify the end of a document node
void	endElement()	End of element
int	getChecksum()	Get the accumulated checksum
String	getDigest()	Get the computed hash
boolean	isChecksumCorrect()	Ask if a correct checksum has been found in the file
boolean	isChecksumFound()	Ask whether a checksum has been found
boolean	isDigestFound()
void	processingInstruction(String target, UnicodeString data, Location locationId, int properties)	Processing Instruction
void	setCheckExistingChecksum(boolean check)	Ask the filter to check any existing checksums found in the file
void	startDocument(int properties)	Start of a document node.
void	startElement(NodeName elemName, SchemaType type, AttributeMap attributes, NamespaceMap namespaces, Location location, int properties)	Notify the start of an element

Methods inherited from class net.sf.saxon.event.ProxyReceiver

close, comment, getNamePool, getNextReceiver, open, setPipelineConfiguration, setSystemId, setUnderlyingReceiver, setUnparsedEntity, usesTypeAnnotations

Methods inherited from class net.sf.saxon.event.SequenceReceiver

append, decompose, flatten, getConfiguration, getErrorCodeForDecomposingFunctionItems, getPipelineConfiguration, getSystemId, handlesAppend

Methods inherited from class java.lang.Object

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

Field Details

SIGMA

public static final String SIGMA

See Also:

• Constant Field Values

SIGMA2

public static final String SIGMA2

See Also:

• Constant Field Values

Constructor Details

CheckSumFilter

public CheckSumFilter(Receiver nextReceiver)

Method Details

setCheckExistingChecksum

public void setCheckExistingChecksum(boolean check)

Ask the filter to check any existing checksums found in the file

Parameters:

check - true if existing checksums are to be checked

startDocument

public void startDocument(int properties)
                   throws XPathException

Description copied from class: ProxyReceiver

Start of a document node.

Specified by:

startDocument in interface Receiver

Overrides:

startDocument in class ProxyReceiver

Parameters:

properties - bit-significant integer indicating properties of the document node. The definitions of the bits are in class ReceiverOption

Throws:

XPathException - if an error occurs

endDocument

public void endDocument()
                 throws XPathException

Description copied from class: ProxyReceiver

Notify the end of a document node

Specified by:

endDocument in interface Receiver

Overrides:

endDocument in class ProxyReceiver

Throws:

XPathException - if an error occurs

append

public void append(Item item,
 Location locationId,
 int copyNamespaces)
            throws XPathException

Append an arbitrary item (node or atomic value) to the output

Specified by:

append in interface Receiver

Overrides:

append in class ProxyReceiver

Parameters:

item - the item to be appended

locationId - the location of the calling instruction, for diagnostics

copyNamespaces - if the item is an element node, this indicates whether its namespaces need to be copied. Values are ReceiverOption.ALL_NAMESPACES; the default (0) means

Throws:

XPathException - if an error occurs

characters

public void characters(UnicodeString chars,
 Location locationId,
 int properties)
                throws XPathException

Character data

Specified by:

characters in interface Receiver

Overrides:

characters in class ProxyReceiver

Parameters:

chars - The characters

locationId - provides information such as line number and system ID.

properties - Bit significant value. The following bits are defined:

DISABLE_ESCAPING

Disable escaping for this text node

USE_CDATA

Output as a CDATA section

Throws:

XPathException - if an error occurs

startElement

public void startElement(NodeName elemName,
 SchemaType type,
 AttributeMap attributes,
 NamespaceMap namespaces,
 Location location,
 int properties)
                  throws XPathException

Notify the start of an element

Specified by:

startElement in interface Receiver

Overrides:

startElement in class ProxyReceiver

Parameters:

elemName - the name of the element.

type - the type annotation of the element.

attributes - the attributes of this element

namespaces - the in-scope namespaces of this element: generally this is all the in-scope namespaces, without relying on inheriting namespaces from parent elements

location - an object providing information about the module, line, and column where the node originated

properties - bit-significant properties of the element node. If there are no relevant properties, zero is supplied. The definitions of the bits are in class ReceiverOption

Throws:

XPathException - if an error occurs

endElement

public void endElement()
                throws XPathException

End of element

Specified by:

endElement in interface Receiver

Overrides:

endElement in class ProxyReceiver

Throws:

XPathException - if an error occurs

processingInstruction

public void processingInstruction(String target,
 UnicodeString data,
 Location locationId,
 int properties)
                           throws XPathException

Processing Instruction

Specified by:

processingInstruction in interface Receiver

Overrides:

processingInstruction in class ProxyReceiver

Parameters:

target - The PI name. This must be a legal name (it will not be checked).

data - The data portion of the processing instruction

locationId - provides information such as line number and system ID.

properties - Additional information about the PI.

Throws:

XPathException - if an error occurs

isChecksumFound

public boolean isChecksumFound()

Ask whether a checksum has been found

Returns:

true if a checksum processing instruction has been found (whether or not the checksum was correct)

isDigestFound

public boolean isDigestFound()

getChecksum

public int getChecksum()

Get the accumulated checksum

Returns:

the checksum of the events passed through the filter so far.

getDigest

public String getDigest()

Get the computed hash

Returns:

the hash

isChecksumCorrect

public boolean isChecksumCorrect()

Ask if a correct checksum has been found in the file

Returns:

true if a checksum has been found, if its value matches, and if no significant data has been encountered after the checksum