org.apache.axiom.om.OMSourcedElement Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.axiom.om;
/**
* Element whose data is backed by an arbitrary Java object. The backing Java object is accessed
* via the {@link OMDataSource} (or {@link OMDataSourceExt}) interface.
*
* An OMSourcedElement can be in one of two states:
*
* - Not Expanded
* - In this state the backing object is used to read and write the XML.
* - Expanded
* - In this state, the OMSourcedElement is backed by a normal OM tree.
*
*
* Here are the steps to place an arbitrary java object into the OM tree:
*
* - Write an {@link OMDataSourceExt} implementation that provides access to your Java
* object.
* - Use {@link OMFactory#createOMElement(OMDataSource, String, OMNamespace)} to create
* the OMSourcedElement.
* - Attach the OMSourcedElement to the tree.
*
*/
public interface OMSourcedElement extends OMElement {
/**
* @return true if tree is expanded or being expanded.
*/
boolean isExpanded();
/**
* @return OMDataSource
*/
OMDataSource getDataSource();
/**
* @deprecated This method is deprecated because its semantics are not clearly defined. In
* particular it is unspecified whether the name of the element may change as a
* result of an invocation of this method.
*/
OMDataSource setDataSource(OMDataSource dataSource);
/**
* Get the object that backs the data source set on this element. This method provides a safe
* way to access that object. It will return a non null value if all of the following conditions
* are satisfied:
*
* - The element is configured with an {@link OMDataSource} of the type specified by the
*
dataSourceClass parameter (in the sense of {@link Class#isInstance(Object)}).
* - The {@link OMDataSourceExt#getObject()} method returns a non null value on the configured
* data source.
*
- The instance can ensure that the content of the element has not been modified. This is
* always the case if the element has not been expanded (i.e. if {@link #isExpanded()} returns
*
false), but the implementation may use additional mechanisms to detect changes
* after expansion of the element.
*
* These are exactly the conditions that must be satisfied if the application code wants to
* implement optimized processing of the sourced element by accessing the backing object.
*
* @param dataSourceClass
* the expected data source class; must be assignment compatible with
* {@link OMDataSourceExt}
* @return the backing Java object or null if the conditions specified above are
* not satisfied
*/
Object getObject(Class dataSourceClass);
}