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/*
* 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 static org.apache.commons.io.IOUtils.EOF;
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.
* </p>
*
* @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);
}
/**
* 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 == EOF) {
close();
}
}
/**
* 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 = ClosedInputStream.INSTANCE;
}
/**
* 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();
}
}
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