| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * 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.openjpa.lib.rop; |
| |
| import org.apache.openjpa.lib.util.Closeable; |
| |
| /** |
| * Interface that allows lazy/custom instantiation of input objects. |
| * {@link ResultList} objects do not necessarily load in data all |
| * at once. Instead, they may lazily load objects as necessary. So, |
| * the lifespan of a {@link ResultObjectProvider} instance is |
| * related to how the application deals with processing the |
| * {@link ResultList} created with a given |
| * {@link ResultObjectProvider} instance. |
| * |
| * @author Marc Prud'hommeaux |
| * @author Patrick Linskey |
| * @author Abe White |
| */ |
| public interface ResultObjectProvider extends Closeable { |
| |
| /** |
| * Return true if this provider supports random access. |
| */ |
| public boolean supportsRandomAccess(); |
| |
| /** |
| * Open the result. This will be called before |
| * {@link #next}, {@link #absolute}, or {@link #size}. |
| */ |
| public void open() throws Exception; |
| |
| /** |
| * Instantiate the current result object. This method will only be |
| * called after {@link #next} or {@link #absolute}. |
| */ |
| public Object getResultObject() throws Exception; |
| |
| /** |
| * Advance the input to the next position. Return <code>true</code> if |
| * there is more data; otherwise <code>false</code>. |
| */ |
| public boolean next() throws Exception; |
| |
| /** |
| * Move to the given 0-based position. This method is |
| * only called for providers that support random access. |
| * Return <code>true</code> if there is data at this position; |
| * otherwise <code>false</code>. This may be invoked in place of |
| * {@link #next}. |
| */ |
| public boolean absolute(int pos) throws Exception; |
| |
| /** |
| * Return the number of items in the input, or {@link Integer#MAX_VALUE} |
| * if the size in unknown. |
| */ |
| public int size() throws Exception; |
| |
| /** |
| * Reset this provider. This is an optional operation. If supported, |
| * it should move the position of the provider to before the first |
| * element. Non-random-access providers may be able to support this |
| * method by re-acquiring all resources as if the result were just opened. |
| */ |
| public void reset() throws Exception; |
| |
| /** |
| * Free the resources associated with this provider. |
| */ |
| public void close() throws Exception; |
| |
| /** |
| * Any checked exceptions that are thrown will be passed to this method. |
| * The provider should re-throw the exception as an appropriate unchecked |
| * exception. |
| */ |
| public void handleCheckedException(Exception e); |
| } |