/*

  * 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.commons.io.input;

 import java.io.IOException;

 import java.io.InputStream;

 /**

  * Proxy stream that closes and discards the underlying stream as soon as the

  * end of input has been reached or when the stream is explicitly closed.

  * Not even a reference to the underlying stream is kept after it has been

  * closed, so any allocated in-memory buffers can be freed even if the

  * client application still keeps a reference to the proxy stream.

  * <p>

  * This class is typically used to release any resources related to an open

  * stream as soon as possible even if the client application (by not explicitly

  * closing the stream when no longer needed) or the underlying stream (by not

  * releasing resources once the last byte has been read) do not do that.

  *

  * @version $Id: AutoCloseInputStream.java 1415850 2012-11-30 20:51:39Z ggregory $

  * @since 1.4

  */

 public class AutoCloseInputStream extends ProxyInputStream {

     /**

      * Creates an automatically closing proxy for the given input stream.

      *

      * @param in underlying input stream

      */

     public AutoCloseInputStream(final InputStream in) {

         super(in);

     }

     /**

      * Closes the underlying input stream and replaces the reference to it

      * with a {@link ClosedInputStream} instance.

      * <p>

      * This method is automatically called by the read methods when the end

      * of input has been reached.

      * <p>

      * Note that it is safe to call this method any number of times. The original

      * underlying input stream is closed and discarded only once when this

      * method is first called.

      *

      * @throws IOException if the underlying input stream can not be closed

      */

     @Override

     public void close() throws IOException {

         in.close();

         in = new ClosedInputStream();

     }

     /**

      * Automatically closes the stream if the end of stream was reached.

      *

      * @param n number of bytes read, or -1 if no more bytes are available

      * @throws IOException if the stream could not be closed

      * @since 2.0

      */

     @Override

     protected void afterRead(final int n) throws IOException {

         if (n == -1) {

             close();

         }

     }

     /**

      * Ensures that the stream is closed before it gets garbage-collected.

      * As mentioned in {@link #close()}, this is a no-op if the stream has

      * already been closed.

      * @throws Throwable if an error occurs

      */

     @Override

     protected void finalize() throws Throwable {

         close();

         super.finalize();

     }

 }