/*
* 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 610010 2008-01-08 14:50:59Z niallp $
* @since Commons IO 1.4
*/
public class AutoCloseInputStream extends ProxyInputStream {
/**
* Creates an automatically closing proxy for the given input stream.
*
* @param in underlying input stream
*/
public AutoCloseInputStream(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
*/
public void close() throws IOException {
in.close();
in = new ClosedInputStream();
}
/**
* Reads and returns a single byte from the underlying input stream.
* If the underlying stream returns -1, the {@link #close()} method is
* called to automatically close and discard the stream.
*
* @return next byte in the stream, or -1 if no more bytes are available
* @throws IOException if the stream could not be read or closed
*/
public int read() throws IOException {
int n = in.read();
if (n == -1) {
close();
}
return n;
}
/**
* Reads and returns bytes from the underlying input stream to the given
* buffer. If the underlying stream returns -1, the {@link #close()} method
* i called to automatically close and discard the stream.
*
* @param b buffer to which bytes from the stream are written
* @return number of bytes read, or -1 if no more bytes are available
* @throws IOException if the stream could not be read or closed
*/
public int read(byte[] b) throws IOException {
int n = in.read(b);
if (n == -1) {
close();
}
return n;
}
/**
* Reads and returns bytes from the underlying input stream to the given
* buffer. If the underlying stream returns -1, the {@link #close()} method
* i called to automatically close and discard the stream.
*
* @param b buffer to which bytes from the stream are written
* @param off start offset within the buffer
* @param len maximum number of bytes to read
* @return number of bytes read, or -1 if no more bytes are available
* @throws IOException if the stream could not be read or closed
*/
public int read(byte[] b, int off, int len) throws IOException {
int n = in.read(b, off, len);
if (n == -1) {
close();
}
return n;
}
/**
* 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
*/
protected void finalize() throws Throwable {
close();
super.finalize();
}
}