javax.batch.api.chunk.AbstractItemReader Maven / Gradle / Ivy

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/*
 * Copyright 2012 International Business Machines Corp.
 * 
 * See the NOTICE file distributed with this work for additional information
 * regarding copyright ownership. 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 javax.batch.api.chunk;

import java.io.Serializable;

/**
 * The AbstractItemReader provides default implementations of less commonly
 * implemented methods.
 * 
 */
public abstract class AbstractItemReader implements ItemReader {
    /**
     * Override this method if the ItemReader requires any open time processing.
     * The default implementation does nothing.
     * 
     * @param last
     *            checkpoint for this ItemReader - may be null.
     * @throws Exception
     *             (or subclass) if an error occurs.
     */
    @Override
    public void open(Serializable checkpoint) throws Exception {
    }

    /**
     * Override this method if the ItemReader requires any close time
     * processing. The default implementation does nothing.
     * 
     * @throws Exception
     *             (or subclass) if an error occurs.
     */
    @Override
    public void close() throws Exception {
    }

    /**
     * Implement read logic for the ItemReader in this method.
     * 
     * @return next item or null
     * @throws Exception
     *             (or subclass) if an error occurs.
     */
    @Override
    public abstract Object readItem() throws Exception;

    /**
     * Override this method if the ItemReader supports checkpoints. The default
     * implementation returns null.
     * 
     * @return checkpoint data
     * @throws Exception
     *             (or subclass) if an error occurs.
     */
    @Override
    public Serializable checkpointInfo() throws Exception {
        return null;
    }
}