Java tutorial
/* * 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 gobblin.util; import java.io.Closeable; import java.io.IOException; import org.apache.commons.pool2.impl.GenericObjectPool; /** * Borrow an object from a {@link GenericObjectPool} and returns it automatically on close. Useful for try with resource. */ public class AutoReturnableObject<T> implements Closeable { private final T object; private final GenericObjectPool<T> pool; private boolean returned; public AutoReturnableObject(GenericObjectPool<T> pool) throws IOException { try { this.pool = pool; this.object = pool.borrowObject(); this.returned = false; } catch (Exception exc) { throw new IOException(exc); } } /** * @return the object borrowed from {@link GenericObjectPool}. * @throws IOException */ public T get() throws IOException { if (this.returned) { throw new IOException(this.getClass().getCanonicalName() + " has already been closed."); } return this.object; } /** * Return the borrowed object to the pool. * @throws IOException */ @Override public void close() throws IOException { try { this.pool.returnObject(this.object); } catch (Exception exc) { throw new IOException(exc); } finally { this.returned = true; } } }