sax: public class: DataFormatFilter

sax
public class: DataFormatFilter [javadoc | source]

java.lang.Object
   org.xml.sax.helpers.XMLFilterImpl
      sax.XMLFilterBase
         sax.DataFormatFilter

All Implemented Interfaces:
LexicalHandler, ErrorHandler, EntityResolver, XMLFilter, ContentHandler, DTDHandler

Filter for data- or field-oriented XML. Code and comments adapted from DataWriter-0.2, written by David Megginson and released into the public domain, without warranty.

This filter adds indentation and newlines to field-oriented XML without mixed content. All added indentation and newlines will be passed on down the filter chain.

In general, all whitespace in an XML document is potentially significant. There is, however, a large class of XML documents where information is strictly fielded: each element contains either character data or other elements, but not both. For this special case, it is possible for a filter to provide automatic indentation and newlines. Note that this class will likely not yield appropriate results for document-oriented XML like XHTML pages, which mix character data and elements together.

This filter will automatically place each start tag on a new line, optionally indented if an indent step is provided (by default, there is no indentation). If an element contains other elements, the end tag will also appear on a new line with leading indentation. Consider, for example, the following code:

DataFormatFilter df = new DataFormatFilter();
df.setContentHandler(new XMLWriter());

df.setIndentStep(2);
df.startDocument();
df.startElement("Person");
df.dataElement("name", "Jane Smith");
df.dataElement("date-of-birth", "1965-05-23");
df.dataElement("citizenship", "US");
df.endElement("Person");
df.endDocument();

This code will produce the following document:

<?xml version="1.0"?>

<Person>
<name>Jane Smith</name>
<date-of-birth>1965-05-23</date-of-birth>
<citizenship>US</citizenship>
</Person>

Also see:

DataUnformatFilter

Fields inherited from sax.XMLFilterBase:
EMPTY_ATTS, LEXICAL_HANDLER_NAMES

Constructor:

Constructor:
public DataFormatFilter() { } Create a new filter.
public DataFormatFilter(XMLReader xmlreader) { super(xmlreader); } Create a new filter. Use the XMLReader provided as the source of events. Parameters: `xmlreader` - The parent in the filter chain.

 public DataFormatFilter() {

}

Create a new filter.

 public DataFormatFilter(XMLReader xmlreader) {
        super(xmlreader);
}

Use the XMLReader provided as the source of events.

Parameters:

xmlreader - The parent in the filter chain.

Method from sax.DataFormatFilter Summary:
characters, endElement, getIndentStep, reset, setIndentStep, startDocument, startElement

Methods from sax.XMLFilterBase:
characters, comment, dataElement, dataElement, dataElement, dataElement, emptyElement, emptyElement, emptyElement, emptyElement, endCDATA, endDTD, endElement, endElement, endEntity, getLexicalHandler, getProperty, parse, setLexicalHandler, setProperty, startCDATA, startDTD, startElement, startElement, startElement, startEntity

Methods from org.xml.sax.helpers.XMLFilterImpl:
characters, endDocument, endElement, endPrefixMapping, error, fatalError, getContentHandler, getDTDHandler, getEntityResolver, getErrorHandler, getFeature, getParent, getProperty, ignorableWhitespace, notationDecl, parse, parse, processingInstruction, resolveEntity, setContentHandler, setDTDHandler, setDocumentLocator, setEntityResolver, setErrorHandler, setFeature, setParent, setProperty, skippedEntity, startDocument, startElement, startPrefixMapping, unparsedEntityDecl, warning

Methods from org.xml.sax.helpers.XMLFilterImpl:

characters, endDocument, endElement, endPrefixMapping, error, fatalError, getContentHandler, getDTDHandler, getEntityResolver, getErrorHandler, getFeature, getParent, getProperty, ignorableWhitespace, notationDecl, parse, parse, processingInstruction, resolveEntity, setContentHandler, setDTDHandler, setDocumentLocator, setEntityResolver, setErrorHandler, setFeature, setParent, setProperty, skippedEntity, startDocument, startElement, startPrefixMapping, unparsedEntityDecl, warning

Methods from java.lang.Object:
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from sax.DataFormatFilter Detail:
public void characters(char[] ch, int start, int length) throws SAXException { state = SEEN_DATA; super.characters(ch, start, length); } Filter a character data event.
public void endElement(String uri, String localName, String qName) throws SAXException { boolean seenElement = (state == SEEN_ELEMENT); state = stateStack.pop(); if (seenElement) { doNewline(); doIndent(); } super.endElement(uri, localName, qName); } Add newline and indentation prior to end tag. If the element has contained other elements, the tag will appear indented on a new line; otherwise, it will appear immediately following whatever came before. The newline and indentation will be passed on down the filter chain through regular characters events.
public int getIndentStep() { return indentStep; } Return the current indent step. Return the current indent step: each start tag will be indented by this number of spaces times the number of ancestors that the element has.
public void reset() { state = SEEN_NOTHING; stateStack = new Stack(); } Reset the filter so that it can be reused. This method is especially useful if the filter failed with an exception the last time through.
public void setIndentStep(int indentStep) { this.indentStep = indentStep; } Set the current indent step.
public void startDocument() throws SAXException { reset(); super.startDocument(); } Filter a start document event. Reset state and pass the event on for further processing.
public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException { if (!stateStack.empty()) { doNewline(); doIndent(); } stateStack.push(SEEN_ELEMENT); state = SEEN_NOTHING; super.startElement(uri, localName, qName, atts); } Add newline and indentation prior to start tag. Each tag will begin on a new line, and will be indented by the current indent step times the number of ancestors that the element has. The newline and indentation will be passed on down the filter chain through regular characters events.

Method from sax.DataFormatFilter Detail:

 public  void characters(char[] ch,
    int start,
    int length) throws SAXException {
        state = SEEN_DATA;
        super.characters(ch, start, length);
}

Filter a character data event.

 public  void endElement(String uri,
    String localName,
    String qName) throws SAXException {
        boolean seenElement = (state == SEEN_ELEMENT);
        state = stateStack.pop();
        if (seenElement) {
            doNewline();
            doIndent();
        }
        super.endElement(uri, localName, qName);
}

If the element has contained other elements, the tag will appear indented on a new line; otherwise, it will appear immediately following whatever came before.

The newline and indentation will be passed on down the filter chain through regular characters events.

 public int getIndentStep() {
        return indentStep;
}

Return the current indent step: each start tag will be indented by this number of spaces times the number of ancestors that the element has.

 public  void reset() {
        state = SEEN_NOTHING;
        stateStack = new Stack();
}

This method is especially useful if the filter failed with an exception the last time through.

 public  void setIndentStep(int indentStep) {
        this.indentStep = indentStep;
}

Set the current indent step.

 public  void startDocument() throws SAXException {
        reset();
        super.startDocument();
}

Reset state and pass the event on for further processing.

 public  void startElement(String uri,
    String localName,
    String qName,
    Attributes atts) throws SAXException {
        if (!stateStack.empty()) {
            doNewline();
            doIndent();
        }
        stateStack.push(SEEN_ELEMENT);
        state = SEEN_NOTHING;
        super.startElement(uri, localName, qName, atts);
}

Each tag will begin on a new line, and will be indented by the current indent step times the number of ancestors that the element has.

The newline and indentation will be passed on down the filter chain through regular characters events.