XMl 教程 ppt加实例

import javax.xml.parsers.SAXParser; mport javax.xml.parsers.SAXParserFactory; import org.xml.sax.XMLReader; import java.io.PrintStream; mport org.xml.sax.helpers.DefaultHandler; import org.xml.sax.Attributes; /** SAX Application to beautify XML documents */ public class XMLPrettyApp { static public void main( String[] args ) throws Exception { // The XML document is supplied as the first argument String myXMLFileURL = args[0]; // Step 1: Create a new instance of SAXParserFactory SAXParserFactory factory = SAXParserFactory.newInstance(); // Step 2: (Optional) Set configuration options factory.setValidating(false); // Step 3: Create a JAXP SAX Parser SAXParser saxParser = factory.newSAXParser(); // Step 4: Get an encapsulated XMLReader XMLReader xmlReader = saxParser.getXMLReader(); // Step 5: Set a Content Handler for events XMLPrettyEvents xmlHndlr = new XMLPrettyEvents( System.out ); xmlReader.setContentHandler( xmlHndlr ); // Step 6: Set an Error Handler XMLPrettyErrors errHndlr = new XMLPrettyErrors( System.err ); xmlReader.setErrorHandler( errHndlr ); // Step 7: Begin the Parsing process xmlReader.parse( myXMLFileURL ); } } /** Simple class to reformat an XML document */ public class XMLPrettyEvents extends DefaultHandler { private PrintStream out; // Normal Output private int offset; // Indentation index private int elementCount; // Count of elements /** Simple constructor that defines an output stream */ MyEventHandler( PrintStream out ) { this.out = out; } /** Print results with indentation */ private void print( String msg ) { out.println( getIndent() + msg ); } /** Return indent based on offset value */ private String getIndent() { StringBuffer indent = new StringBuffer(); for (int i = 0; i < offset; i++) { indent.append(" "); } return indent.toString(); } /** Initialize variables on document start */ public void startDocument() { print("Start of Document"); offset = 0; } /** Display tally on document end */ public void endDocument() { } /** Display the element start tag */ public void startElement( String uri, String localname, String qName, Attributes attrs) { // Build a representative start tag String e = "<" + qName; for (int x = 0; x < attrs.getLength(); x++) { e += " "+attrs.getQName(x)+"='"+attrs.getValue(x)+"'"; } e += ">"; print(e); // Output the start tag info off } /** Display the closing tag for the element */ public void endElement( String uri, String localname, String qName ) { offset--; // Decrement the offset pointer elementCount++; // Increment the element counter print("</" + qName + ">"); // Output the end tag info } /** Output the text block inside an element */ public void characters( char[] ch, int start, int length ) { // Builds a string based on char array StringBuffer sb = new StringBuffer(); sb.append( ch, start, length ); // Output resulting text value print( sb.toString() ); } } /** My Custom XML Error Handler Class */ public class MyErrorHandler implements ErrorHandler { private PrintStream out; /** Constructor - Set output stream for warnings */ MyErrorHandler( PrintStream out ) { this.out = out; } /** Warnings - Non fatal, log it and continue */ public void warning(SAXParseException spe) throws SAXException { out.println("Warning: " + spe.getMessage()); } /** Errors - Throw an exception with error info */ public void error(SAXParseException spe) throws SAXException { throw new SAXException( "Error: " + getExceptionInfo(spe) ); } /** FatalErrors - Throw an exception with fatal error info */ public void fatalError(SAXParseException spe) throws SAXException { throw new SAXException( "Fatal: " + getExceptionInfo(spe) ); } /** Gather some Exception information */ private String getExceptionInfo(SAXParseException spe) { return "URL=" + spe.getSystemId() + " Line=" + spe.getLineNumber() + ": " + spe.getMessage(); } }