ProviderFactory.java

/*
 * ProviderFactory.java January 2010
 *
 * Copyright (C) 2010, Niall Gallagher <niallg@users.sf.net>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 
 * implied. See the License for the specific language governing 
 * permissions and limitations under the License.
 */

package org.simpleframework.xml.stream;

/**
 * The <code>ProviderFactory</code> object is used to instantiate a
 * provider of XML parsing to the framework. This scans the classpath
 * for the classes required for StAX, if they are present then this 
 * is what will be used to process XML. If however StAX can not be
 * used then a DOM implementation is provided. A DOM provider as a
 * default suits most Java profiles as it is a very common parser.
 * 
 * @author Niall Gallagher
 * 
 * @see org.simpleframework.xml.stream.NodeBuilder
 */
final class ProviderFactory {

   /**
    * This is used to acquire the <code>Provider</code> to be used 
    * to process XML documents. The provider returned is determined
    * by scanning the classpath for StAX dependencies, if they are
    * available then the provider used is StAX otherwise it is DOM. 
    * Scanning the classpath in this manner ensures the most suitable
    * parser is used for the host platform.
    * 
    * @return this returns the provider that has been instantiate
    */
   public static Provider getInstance() {
      try {
         try {
            return new StreamProvider();
         } catch(Throwable e) {
            return new PullProvider();
         }
      } catch(Throwable e) {
         return new DocumentProvider();
      }
   }
}