https://openjdk.java.net/ 
/*
 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.xml.internal.bind.api;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import javax.xml.bind.ValidationEventHandler;
import javax.xml.bind.annotation.XmlAnyElement;

import com.sun.istack.internal.NotNull;
import com.sun.istack.internal.Nullable;


Dynamically locates classes to represent elements discovered during the unmarshalling.


THIS INTERFACE IS SUBJECT TO CHANGE WITHOUT NOTICE.

Background


 JAXBContext.newInstance(Class<?>...) requires that application informs JAXB about all the classes that it may see in the instance document. While this allows JAXB to take time to optimize the unmarshalling, it is sometimes inconvenient for applications. 
 This is where ClassResolver comes to resucue. 
 A ClassResolver instance can be specified on Unmarshaller via Unmarshaller.setProperty(String, Object) as follows: 
unmarshaller.setProperty( ClassResolver.class.getName(), new MyClassResolverImpl() );



 When an Unmarshaller encounters (i) an unknown root element or (ii) unknown elements where unmarshaller is trying to unmarshal into XmlAnyElement with lax=true, unmarshaller calls resolveElementName(String, String) method to see if the application may be able to supply a class that corresponds to that class. 
 When a Class is returned, a new JAXBContext is created with all the classes known to it so far, plus a new class returned. This operation may fail (for example because of some conflicting annotations.) This failure is handled just like Exceptions thrown from resolveElementName(String, String). 
Author:Kohsuke Kawaguchi
Since:2.1
/**
 * Dynamically locates classes to represent elements discovered during the unmarshalling.
 *
 * <p>
 * <b>THIS INTERFACE IS SUBJECT TO CHANGE WITHOUT NOTICE.</b>
 *
 * <h2>Background</h2>
 * <p>
 * {@link JAXBContext#newInstance(Class...)} requires that application informs JAXB
 * about all the classes that it may see in the instance document. While this allows
 * JAXB to take time to optimize the unmarshalling, it is sometimes inconvenient
 * for applications.
 *
 * <p>
 * This is where {@link ClassResolver} comes to resucue.
 *
 * <p>
 * A {@link ClassResolver} instance can be specified on {@link Unmarshaller} via
 * {@link Unmarshaller#setProperty(String, Object)} as follows:
 *
 * <pre>
 * unmarshaller.setProperty( ClassResolver.class.getName(), new MyClassResolverImpl() );
 * </pre>
 *
 * <p>
 * When an {@link Unmarshaller} encounters (i) an unknown root element or (ii) unknown
 * elements where unmarshaller is trying to unmarshal into {@link XmlAnyElement} with
 * {@code lax=true}, unmarshaller calls {@link #resolveElementName(String, String)}
 * method to see if the application may be able to supply a class that corresponds
 * to that class.
 *
 * <p>
 * When a {@link Class} is returned, a new {@link JAXBContext} is created with
 * all the classes known to it so far, plus a new class returned. This operation
 * may fail (for example because of some conflicting annotations.) This failure
 * is handled just like {@link Exception}s thrown from
 * {@link ClassResolver#resolveElementName(String, String)}.
 *
 * @author Kohsuke Kawaguchi
 * @since 2.1
 */
public abstract class ClassResolver {
    
JAXB calls this method when it sees an unknown element.


See the class javadoc for details.

Params:
  • nsUri – 
     Namespace URI of the unknown element. Can be empty but never null.
  • localName – 
     Local name of the unknown element. Never be empty nor null.
Throws:
  • Exception –  Throwing any RuntimeException causes the unmarshaller to stop immediately. The exception will be propagated up the call stack. Throwing any other checked Exception results in the error reproted to ValidationEventHandler (just like any other error during the unmarshalling.)
Returns: If a non-null class is returned, it will be used to unmarshal this element. If null is returned, the resolution is assumed to be failed, and the unmarshaller will behave as if there was no ClassResolver to begin with (that is, to report it to ValidationEventHandler, then move on.)
/**
     * JAXB calls this method when it sees an unknown element.
     *
     * <p>
     * See the class javadoc for details.
     *
     * @param nsUri
     *      Namespace URI of the unknown element. Can be empty but never null.
     * @param localName
     *      Local name of the unknown element. Never be empty nor null.
     *
     * @return
     *      If a non-null class is returned, it will be used to unmarshal this element.
     *      If null is returned, the resolution is assumed to be failed, and
     *      the unmarshaller will behave as if there was no {@link ClassResolver}
     *      to begin with (that is, to report it to {@link ValidationEventHandler},
     *      then move on.)
     *
     * @throws Exception
     *      Throwing any {@link RuntimeException} causes the unmarshaller to stop
     *      immediately. The exception will be propagated up the call stack.
     *      Throwing any other checked {@link Exception} results in the error
     *      reproted to {@link ValidationEventHandler} (just like any other error
     *      during the unmarshalling.)
     */
    public abstract @Nullable Class<?> resolveElementName(@NotNull String nsUri, @NotNull String localName) throws Exception;
}