jpdlparser.java

jBpm是一个灵活可扩展的工作流管理系统。作为jBpm运行时server输入的业务流程使用简单强大的语言表达并打包在流程档案中

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005, JBoss Inc., and individual contributors as indicated
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jbpm.jpdl.xml;

import java.io.IOException;
import java.io.Serializable;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.dom4j.Document;
import org.dom4j.io.SAXReader;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.XMLReader;

/**
 * Validate an XML document using JAXP techniques and an XML Schema. This helper
 * class wraps the processing of a schema to aid in schema validation throughout
 * the product.
 * 
 * @author Tom Baeyens
 * @author Jim Rigsbee
 */
public class JpdlParser implements Serializable {

  private static final long serialVersionUID = 1L;
  static final EntityResolver JPDL_ENTITY_RESOLVER = new JpdlEntityResolver();

  public static Document parse(InputSource inputSource, ProblemListener problemListener) throws Exception {
    Document document = null;
    SAXReader saxReader = createSaxReader(problemListener);
    document = saxReader.read(inputSource);
    return document;
  }

  public static SAXReader createSaxReader(ProblemListener problemListener) throws Exception {
    XMLReader xmlReader = createXmlReader();
    SAXReader saxReader = new SAXReader(xmlReader);
    saxReader.setErrorHandler(new JpdlErrorHandler(problemListener));
    saxReader.setEntityResolver(JPDL_ENTITY_RESOLVER);
    return saxReader;
  }

  public static XMLReader createXmlReader() throws Exception {
    SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
    saxParserFactory.setValidating(true);
    saxParserFactory.setNamespaceAware(true);
    SAXParser saxParser = saxParserFactory.newSAXParser();
    XMLReader xmlReader = saxParser.getXMLReader();
    
    try {
      saxParser.setProperty("http://java.sun.com/xml/jaxp/properties/schemaLanguage", "http://www.w3.org/2001/XMLSchema");
    } catch (SAXException e){
      log.warn("couldn't set xml parser property 'http://java.sun.com/xml/jaxp/properties/schemaLanguage' to 'http://www.w3.org/2001/XMLSchema'", e);
    }
    
    try {
      saxParser.setProperty(
    		  "http://apache.org/xml/properties/schema/external-schemaLocation", 
    		  "http://jbpm.org/3/jpdl http://jbpm.org/jpdl-3.0.xsd " +
    		  "urn:jbpm.org:jpdl-3.0 http://jbpm.org/jpdl-3.0.xsd " +
    		  "urn:jbpm.org:jpdl-3.1 http://jbpm.org/jpdl-3.1.xsd");
    } catch (SAXException e){
      log.warn("couldn't set xml parser property 'http://apache.org/xml/properties/schema/external-schemaLocation'", e);
    }

    try {
      xmlReader.setFeature("http://apache.org/xml/features/validation/dynamic", true);
    } catch (SAXException e){
      log.warn("couldn't set xml parser feature 'http://apache.org/xml/features/validation/dynamic'", e);
    }
    return xmlReader;
  }

  static class JpdlErrorHandler implements ErrorHandler, Serializable {
    private static final long serialVersionUID = 1L;
    ProblemListener problemListener = null;
    JpdlErrorHandler(ProblemListener problemListener) {
      this.problemListener = problemListener;
    }
    public void warning(SAXParseException pe) {
      addProblem(Problem.LEVEL_WARNING, "line " + pe.getLineNumber() + ": " + pe.getMessage(), pe);
    }
    public void error(SAXParseException pe) {
      addProblem(Problem.LEVEL_ERROR, "line " + pe.getLineNumber() + ": " + pe.getMessage(), pe);
    }
    public void fatalError(SAXParseException pe) {
      addProblem(Problem.LEVEL_FATAL, "line " + pe.getLineNumber() + ": " + pe.getMessage(), pe);
    }
    void addProblem(int level, String description, Throwable exception) {
      problemListener.addProblem(new Problem(level, description, exception));
    }
  }
  
  static class JpdlEntityResolver implements EntityResolver, Serializable {
    private static final long serialVersionUID = 1L;

    public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {
      InputSource inputSource = null;
      log.debug("resolving schema reference publicId("+publicId+") systemId("+systemId+")");
      
      if ("http://jbpm.org/jpdl-3.1.xsd".equals(systemId)) {
        log.debug("providing input source to local 'jpdl-3.1.xsd' resource");
        inputSource = new InputSource(this.getClass().getResourceAsStream("jpdl-3.1.xsd"));
        
      } else if ("http://jbpm.org/jpdl-3.0.xsd".equals(systemId)) {
        log.debug("providing input source to local 'jpdl-3.0.xsd' resource");
        inputSource = new InputSource(this.getClass().getResourceAsStream("jpdl-3.0.xsd"));
        
      } else {
        log.debug("original systemId as input source");
        inputSource = new InputSource(systemId);
      }
      return inputSource;
    }
  }

  private static final Log log = LogFactory.getLog(JpdlParser.class);
}