v1/src/xmlpublic/org/apache/xmlbeans/XmlFactoryHook.java

/*
* The Apache Software License, Version 1.1
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*
* Copyright (c) 2003 The Apache Software Foundation.  All rights 
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* 1. Redistributions of source code must retain the above copyright
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*    if any, must include the following acknowledgment:  
*       "This product includes software developed by the
*        Apache Software Foundation (http://www.apache.org/)."
*    Alternately, this acknowledgment may appear in the software itself,
*    if and wherever such third-party acknowledgments normally appear.
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* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation and was
* originally based on software copyright (c) 2000-2003 BEA Systems 
* Inc., <http://www.bea.com/>. For more information on the Apache Software
* Foundation, please see <http://www.apache.org/>.
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package org.apache.xmlbeans;

import org.w3c.dom.Node;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;

import weblogic.xml.stream.XMLInputStream;
import weblogic.xml.stream.XMLStreamException;

/**
 * A hook for the XML Bean Factory mechanism.
 * Provided for advanced users who wish to provide their own
 * implementation of the Factory.parse methods. This is used, for example,
 * to defer reading XML streams until needed.
 * <p>
 * To use the hook, call XmlFactoryHook.ThreadContext.setHook(), passing
 * your own XmlFactoryHook implementation.  Then every call to a Factory
 * method will be delgated to your hook.
 *
 * <pre>
 * MyHook hook = new MyHook();
 * XmlFactoryHook.ThreadContext.setHook(hook);
 * // this results in a call to hook.parse(...)
 * XmlObject.Factory.parse(new File("test.xml"));
 * </pre>
 * 
 * If the hook needs to turn around and invoke the built-in parsers, then
 * it should do so by calling the appropriate method on the passed
 * SchemaTypeLoader.  Since SchemaTypeLoader.parse() methods delegate
 * to the registered hook, a hook that wishes to actually invoke the
 * default parser without having itself called back again should
 * unregister itself before calling loader.parse(), and then re-register
 * itself again after the call.
 * <pre>
 * void parse(SchemaTypeLoader loader, ...)
 * {
 *     XmlFactoryHook remember = XmlFactoryHook.ThreadContext.getHook();
 *     XmlFactoryHook.ThreadContext.setHook(null);
 *     loader.parse(...); // isn't hooked.
 *     XmlFactoryHook.ThreadContext.setHook(remember);
 * }
 * </pre>
 */
public interface XmlFactoryHook
{
    /** Hooks Factory.newInstance calls */
    public XmlObject newInstance ( SchemaTypeLoader loader, SchemaType type, XmlOptions options );
    /** Hooks Factory.parse calls */
    public XmlObject parse ( SchemaTypeLoader loader, String xmlText, SchemaType type, XmlOptions options ) throws XmlException;
    /** Hooks Factory.parse calls */
    public XmlObject parse ( SchemaTypeLoader loader, InputStream jiois, SchemaType type, XmlOptions options ) throws XmlException, IOException;
    /** Hooks Factory.parse calls */
    public XmlObject parse ( SchemaTypeLoader loader, Reader jior, SchemaType type, XmlOptions options ) throws XmlException, IOException;
    /** Hooks Factory.parse calls */
    public XmlObject parse ( SchemaTypeLoader loader, Node node, SchemaType type, XmlOptions options ) throws XmlException;
    /** Hooks Factory.parse calls */
    public XmlObject parse ( SchemaTypeLoader loader, XMLInputStream xis, SchemaType type, XmlOptions options ) throws XmlException, XMLStreamException;
    /** Hooks Factory.newXmlSaxHandler calls */
    public XmlSaxHandler newXmlSaxHandler ( SchemaTypeLoader loader, SchemaType type, XmlOptions options );

    /**
     * Used to manage the XmlFactoryHook for the current thread.
     */ 
    public final static class ThreadContext
    {
        private static ThreadLocal threadHook = new ThreadLocal();
        
        /**
         * Returns the current thread's hook, or null if none.
         */ 
        public static XmlFactoryHook getHook()
        {
            return (XmlFactoryHook)threadHook.get();
        }

        /**
         * Sets the hook for the current thread.
         */ 
        public static void setHook(XmlFactoryHook hook)
        {
            threadHook.set(hook);
        }

        // provided to prevent unwanted construction
        private ThreadContext()
        {
        }
    }
}