Class 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.

    • Constructor Detail

      • CheckSumFilter

        public CheckSumFilter​(Receiver nextReceiver)
    • Method Detail

      • 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
      • 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
      • 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