Java tutorial
/* * @(#)InputParser.java * * Copyright 2003-2004 Sun Microsystems, Inc. All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * 1. Redistribution of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * 2. Redistribution in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * Neither the name of Sun Microsystems, Inc. or the names of contributors may * be used to endorse or promote products derived from this software without * specific prior written permission. * * This software is provided "AS IS," without a warranty of any kind. ALL * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN") * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. * * You acknowledge that this software is not designed or intended for use in * the design, construction, operation or maintenance of any nuclear facility. */ package com.connexta.arbitro.ctx; import java.io.File; import java.io.InputStream; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.connexta.arbitro.ParsingException; import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.ErrorHandler; import org.xml.sax.SAXException; import org.xml.sax.SAXParseException; /** * A package-private helper that provides a single static routine for parsing input based on the * context schema. * * @since 1.0 * @author Seth Proctor */ public class InputParser implements ErrorHandler { // the schema file, if provided private File schemaFile; // the single reference, which is null unless a schema file is provided private static InputParser ipReference = null; // the property string to set to turn on validation private static final String CONTEXT_SCHEMA_PROPERTY = "com.sun.xacml.ContextSchema"; // the logger we'll use for all messages private static Log logger = LogFactory.getLog(InputParser.class); // standard strings for setting validation private static final String JAXP_SCHEMA_LANGUAGE = "http://java.sun.com/xml/jaxp/properties/schemaLanguage"; private static final String W3C_XML_SCHEMA = "http://www.w3.org/2001/XMLSchema"; private static final String JAXP_SCHEMA_SOURCE = "http://java.sun.com/xml/jaxp/properties/schemaSource"; /** * Look for the property that names the schema, and if it exists get the file name and create a * single InputParser instance */ static { String schemaName = System.getProperty(CONTEXT_SCHEMA_PROPERTY); if (schemaName != null) ipReference = new InputParser(new File(schemaName)); }; /** * Constructor that takes the schema file. */ private InputParser(File schemaFile) { this.schemaFile = schemaFile; } /** * Tries to Parse the given output as a Context document. * * @param input the stream to parse * @param rootTag either "Request" or "Response" * * @return the root node of the request/response * * @throws ParsingException if a problem occurred parsing the document */ public static Node parseInput(InputStream input, String rootTag) throws ParsingException { NodeList nodes = null; try { DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); factory.setIgnoringComments(true); DocumentBuilder builder = null; // as of 1.2, we always are namespace aware factory.setNamespaceAware(true); if (ipReference == null) { // we're not validating factory.setValidating(false); builder = factory.newDocumentBuilder(); } else { // we are validating factory.setValidating(true); factory.setAttribute(JAXP_SCHEMA_LANGUAGE, W3C_XML_SCHEMA); factory.setAttribute(JAXP_SCHEMA_SOURCE, ipReference.schemaFile); builder = factory.newDocumentBuilder(); builder.setErrorHandler(ipReference); } Document doc = builder.parse(input); nodes = doc.getElementsByTagName(rootTag); } catch (Exception e) { throw new ParsingException("Error tring to parse " + rootTag + "Type", e); } if (nodes.getLength() != 1) throw new ParsingException("Only one " + rootTag + "Type allowed " + "at the root of a Context doc"); return nodes.item(0); } /** * Standard handler routine for the XML parsing. * * @param exception information on what caused the problem */ public void warning(SAXParseException exception) throws SAXException { if (logger.isWarnEnabled()) logger.warn("Warning on line " + exception.getLineNumber() + ": " + exception.getMessage()); } /** * Standard handler routine for the XML parsing. * * @param exception information on what caused the problem * * @throws SAXException always to halt parsing on errors */ public void error(SAXParseException exception) throws SAXException { if (logger.isErrorEnabled()) logger.error("Error on line " + exception.getLineNumber() + ": " + exception.getMessage()); throw new SAXException("invalid context document"); } /** * Standard handler routine for the XML parsing. * * @param exception information on what caused the problem * * @throws SAXException always to halt parsing on errors */ public void fatalError(SAXParseException exception) throws SAXException { if (logger.isErrorEnabled()) logger.error("FatalError on line " + exception.getLineNumber() + ": " + exception.getMessage()); throw new SAXException("invalid context document"); } }