Content Handler First SAX Example

Content Handler
startDocument()
Receive notification of the beginning of a document.
startElement (String namespaceURI,
String localName, String qName,
Attributes atts)
Receive notification of the beginning of an element.
characters (char[] ch, int start, int length)
Receive notification of character data.
endElement(String namespaceURI,
String localName, String qName)
Receive notification of the end of an element.
endDocument()
Receive notification of the end of a document.
© Helmar Burkhart
•
Webtechnologies (CS211) • Lesson 8: XML Technologies
8-41
First SAX Example
import org.xml.sax.helpers.DefaultHandler;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
public class SAX1 extends DefaultHandler {
private String doc;
public SAX1(String doc){
this.doc=doc;
}
public void startDocument() {
System.out.println("document " + doc +
" started");
}
public void endDocument() {
System.out.println("document ended");
}
© Helmar Burkhart
•
Webtechnologies (CS211) • Lesson 8: XML Technologies
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First SAX Example (contd.)
public static void main(String args[]) throws
Exception {
SAXParserFactory spf =
SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
sp.parse(args[0]+ ".xml", new SAX1(args[0]+
".xml"));
}
<?xml
version="1.0" standalone="yes"?>
<sample>
<step duration="1">abc</step>
<step duration="2">abc</step>
</sample>
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•
Test document
sample.xml
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More SAX Examples
• SAX2:
• SAX3:
• SAX4:
Generation of parsing events.
More detailed parsing events.
Count elements using hash
map.
• pizza: Transform XML to HTML.
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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Parser Modes
Namespace awareness has explicitly to be set:
• factory.setNamespaceAware(true);
Check for validity has explicitly to be set:
• factory.setValidating(true);
© Helmar Burkhart
•
Webtechnologies (CS211) • Lesson 8: XML Technologies
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Error Handler is Mandatory
public void error(SAXParseException e)
throws SAXParseException
{
throw e;
}
public void warning(SAXParseException err)
throws SAXParseException
{
System.out.println("** Warning"
+ ", line " + err.getLineNumber()
+ ", uri " + err.getSystemId());
System.out.println("
" + err.getMessage());
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
8-46
Reading Characters
• SAX-Parsers may return all contiguous
character data in a single chunk, but
they may also be split into several
chunks.
• Application program has to collect all
characters in a buffer in order to fulfill
this requirement.
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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Links
• JAXP:
java.sun.com/xml/jaxp/
• SAX:
www.saxproject.org/
• Webservices Tutorial Chapter 7: SAX
java.sun.com/webservices/docs/1.3/tutorial/doc/index.html
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
8-48
DOM Parser
import org.w3c.dom.*;
import org.xml.sax.*;
import javax.xml.parsers.*;
import java.io.*;
public class SchachDOMPrinter {
static private DocumentBuilder builder;
public SchachDOMPrinter() throws Exception{
}
public void print(String fileName) throws SAXException, IOException {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setValidating(true);
try {
builder = factory.newDocumentBuilder();
builder.setErrorHandler(new MyErrorHandler());
Document document = builder.parse(fileName);
© Helmar Burkhart
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Beispiele
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE SCHACH SYSTEM "dtd/schach.dtd">
<SCHACH>
<SCHACHBRETT>
<WEISS>
<KOENIG><POSITION SPALTE="G" REIHE="1" /></KOENIG>
<LAUEFER><POSITION SPALTE="D" REIHE="6" /></LAUEFER>
<TURM><POSITION SPALTE="E" REIHE="1" /></TURM>
<BAUER><POSITION SPALTE="A" REIHE="4" /></BAUER>
<BAUER><POSITION SPALTE="B" REIHE="3" /></BAUER>
<BAUER><POSITION SPALTE="C" REIHE="2" /></BAUER>
<BAUER><POSITION SPALTE="F" REIHE="2" /></BAUER>
<BAUER><POSITION SPALTE="G" REIHE="2" /></BAUER>
<BAUER><POSITION SPALTE="H" REIHE="5" /></BAUER>
</WEISS>
<SCHWARZ>
<KOENIG><POSITION SPALTE="B" REIHE="6" /></KOENIG>
<DAME><POSITION SPALTE="A" REIHE="7" /></DAME>
<BAUER><POSITION SPALTE="D" REIHE="4" /></BAUER>
</SCHWARZ>
</SCHACHBRETT>
</SCHACH>
© Helmar Burkhart
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Schach DTD
<!ELEMENT SCHACH (SCHACHBRETT*)>
<!ELEMENT SCHACHBRETT (WEISS, SCHWARZ)>
<!ENTITY % figur
"KOENIG,
DAME?,
LAUEFER?, LAUEFER?,
TURM?, TURM?,
PFERD?, PFERD?,
BAUER?, BAUER?, BAUER?, BAUER?,
BAUER?, BAUER?, BAUER?, BAUER?"
>
<!ELEMENT WEISS (%figur;)>
<!ELEMENT SCHWARZ (%figur;)>
<!ELEMENT POSITION EMPTY>
<!ATTLIST POSITION
SPALTE (A|B|C|D|E|F|G|H) #REQUIRED
REIHE (1|2|3|4|5|6|7|8) #REQUIRED
>
<!ELEMENT KOENIG (POSITION)>
<!ELEMENT DAME (POSITION)>
<!ELEMENT LAUEFER (POSITION)>
<!ELEMENT TURM (POSITION)>
<!ELEMENT PFERD (POSITION)>
<!ELEMENT BAUER (POSITION)>
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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Java XML Binding (JAXB)
Zusammengefasst erzeugt der im JAXB
enthaltene Compiler speziell angepassten
Quelltext, um spezielle XML-Dateien zu lesen
und zu schreiben.
Der Übergang vom XML-Dokument
zum Objektbaum wird als unmarshalling und
der Übergang von den Objekten zu XMLDokument als marshalling bezeichnet.
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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XML
<---->
JAVA
Compile xjc
Schema
Classes
instance of
follows
unmarshal
Objects
Document
marshal
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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Spez. Dokument -> Java Klassen
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1. Schema
<xs:element name = "book">
<xs:complexType>
<xs:sequence>
<xs:element ref = "title"/>
<xs:element ref = "contents"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name = "title" type = "xs:string"/>
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Bsp: unmarshal()
// Import Teil
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import jax.inhalt.*;
public class Main {
public static void main( String[] args ) {
© Helmar Burkhart
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Bsp: unmarshal() (Fortsetzung)
try {
JAXBContext jc = JAXBContext.newInstance( "jax.inhalt" );
Unmarshaller u = jc.createUnmarshaller();
Book book =
(Book)u.unmarshal( new FileInputStream( "xml/inhalt.xml" ) );
System.out.println( "Ship the following items to: " );
Contents contents = book.getContents();
displayContents ( contents );
} catch( JAXBException je ) {
je.printStackTrace();
} catch( IOException ioe ) {
ioe.printStackTrace();
}
}
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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Bsp: unmarshal() (Fortsetzung)
public static void displayContents( Contents contents ) {
List chapterList = contents.getChapter();
for( Iterator iter = chapterList.iterator(); iter.hasNext(); ) {
ContentsType.ChapterType Chapter =
(ContentsType.ChapterType)iter.next();
System.out.println( "\t" + " Chapter: \"" +Chapter.getTitle() + "\"" );
List topicList = Chapter.getTopic();
for( Iterator iter2 = topicList.iterator(); iter2.hasNext(); ) {
ContentsType.ChapterType.TopicType Topic =
(ContentsType.ChapterType.TopicType)iter2.next();
System.out.println( "\t" + " --- Topic: \"" + Topic.getName()+"\"" );
}
}
}
}
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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Bsp: marshal()
...try
{
JAXBContext jc = JAXBContext.newInstance( "jax.inhalt" );
ObjectFactory objFactory = new ObjectFactory();
// create an empty Book
Book book = objFactory.createBook();
Title title = objFactory.createTitle();
book.setTitle("test jax buch");
Contents contents = objFactory.createContents();
book.setContents(contents);
...
Marshaller m = jc.createMarshaller();
m.setProperty( Marshaller.JAXB_FORMATTED_OUTPUT Boolean.TRUE);
m.marshal( book, System.out );
...
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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Links
• JAXB:
java.sun.com/xml/jaxb/
• Webservices Tutorial Chapter 2: JAXB
http://java.sun.com/webservices/docs/1.5/tutorial/doc/index.html
© Helmar Burkhart
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Webtechnologies (CS211) • Lesson 8: XML Technologies
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