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/*
* Copyright 2000-2013 Vaadin Ltd.
*
* 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 com.vaadin.data;
import java.io.Serializable;
import com.vaadin.data.Validator.InvalidValueException;
/**
* <p>
* Defines the interface to commit and discard changes to an object, supporting
* buffering.
*
* <p>
* In <i>buffered</i> mode the initial value is read from the data source and
* then buffered. Any subsequential writes or reads will be done on the buffered
* value. Calling {@link #commit()} will write the buffered value to the data
* source while calling {@link #discard()} while discard the buffered value and
* re-read the value from the data source.
*
* <p>
* In <i>non-buffered</i> mode the value is always read directly from the data
* source. Any write is done directly to the data source with no buffering in
* between. Reads are also done directly from the data source. Calling
* {@link #commit()} or {@link #discard()} in this mode is efficiently a no-op.
*
* @author Vaadin Ltd.
* @since 3.0
*/
public interface Buffered extends Serializable {
/**
* Updates all changes since the previous commit to the data source. The
* value stored in the object will always be updated into the data source
* when <code>commit</code> is called.
*
* @throws SourceException
* if the operation fails because of an exception is thrown by
* the data source. The cause is included in the exception.
* @throws InvalidValueException
* if the operation fails because validation is enabled and the
* values do not validate
*/
public void commit() throws SourceException, InvalidValueException;
/**
* Discards all changes since last commit. The object updates its value from
* the data source.
*
* @throws SourceException
* if the operation fails because of an exception is thrown by
* the data source. The cause is included in the exception.
*/
public void discard() throws SourceException;
/**
* Sets the buffered mode to the specified status.
* <p>
* When in buffered mode, an internal buffer will be used to store changes
* until {@link #commit()} is called. Calling {@link #discard()} will revert
* the internal buffer to the value of the data source.
* <p>
* When in non-buffered mode both read and write operations will be done
* directly on the data source. In this mode the {@link #commit()} and
* {@link #discard()} methods serve no purpose.
*
* @param buffered
* true if buffered mode should be turned on, false otherwise
* @since 7.0
*/
public void setBuffered(boolean buffered);
/**
* Checks the buffered mode
*
* @return true if buffered mode is on, false otherwise
* @since 7.0
*/
public boolean isBuffered();
/**
* Tests if the value stored in the object has been modified since it was
* last updated from the data source.
*
* @return <code>true</code> if the value in the object has been modified
* since the last data source update, <code>false</code> if not.
*/
public boolean isModified();
/**
* An exception that signals that one or more exceptions occurred while a
* buffered object tried to access its data source or if there is a problem
* in processing a data source.
*
* @author Vaadin Ltd.
* @since 3.0
*/
@SuppressWarnings("serial")
public class SourceException extends RuntimeException implements
Serializable {
/** Source class implementing the buffered interface */
private final Buffered source;
/** Original cause of the source exception */
private Throwable[] causes = {};
/**
* Creates a source exception that does not include a cause.
*
* @param source
* the source object implementing the Buffered interface.
*/
public SourceException(Buffered source) {
this.source = source;
}
/**
* Creates a source exception from multiple causes.
*
* @param source
* the source object implementing the Buffered interface.
* @param causes
* the original causes for this exception.
*/
public SourceException(Buffered source, Throwable... causes) {
this.source = source;
this.causes = causes;
}
/**
* Gets the cause of the exception.
*
* @return The (first) cause for the exception, null if no cause.
*/
@Override
public final Throwable getCause() {
if (causes.length == 0) {
return null;
}
return causes[0];
}
/**
* Gets all the causes for this exception.
*
* @return throwables that caused this exception
*/
public final Throwable[] getCauses() {
return causes;
}
/**
* Gets a source of the exception.
*
* @return the Buffered object which generated this exception.
*/
public Buffered getSource() {
return source;
}
}
}
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