org.apache.poi.util.BoundedInputStream Maven / Gradle / Ivy
Show all versions of apache-poi Show documentation
/*
* 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.poi.util;
import java.io.IOException;
import java.io.InputStream;
/**
* This is a stream that will only supply bytes up to a certain length - if its
* position goes above that, it will stop.
*
* This is useful to wrap ServletInputStreams. The ServletInputStream will block
* if you try to read content from it that isn't there, because it doesn't know
* whether the content hasn't arrived yet or whether the content has finished.
* So, one of these, initialized with the Content-length sent in the
* ServletInputStream's header, will stop it blocking, providing it's been sent
* with a correct content length.
*
* @version $Id$
* @since Commons IO 2.0
*/
public class BoundedInputStream extends InputStream {
/** the wrapped input stream */
private final InputStream in;
/** the max length to provide */
private final long max;
/** the number of bytes already returned */
private long pos;
/** the marked position */
private long mark = -1;
/** flag if close shoud be propagated */
private boolean propagateClose = true;
/**
* Creates a new BoundedInputStream that wraps the given input
* stream and limits it to a certain size.
*
* @param in The wrapped input stream
* @param size The maximum number of bytes to return
*/
public BoundedInputStream(InputStream in, long size) {
// Some badly designed methods - eg the servlet API - overload length
// such that "-1" means stream finished
this.max = size;
this.in = in;
}
/**
* Creates a new BoundedInputStream that wraps the given input
* stream and is unlimited.
*
* @param in The wrapped input stream
*/
public BoundedInputStream(InputStream in) {
this(in, -1);
}
/**
* Invokes the delegate's read() method if
* the current position is less than the limit.
* @return the byte read or -1 if the end of stream or
* the limit has been reached.
* @throws IOException if an I/O error occurs
*/
@Override
public int read() throws IOException {
if (max>=0 && pos==max) {
return -1;
}
int result = in.read();
pos++;
return result;
}
/**
* Invokes the delegate's read(byte[]) method.
* @param b the buffer to read the bytes into
* @return the number of bytes read or -1 if the end of stream or
* the limit has been reached.
* @throws IOException if an I/O error occurs
*/
@Override
public int read(byte[] b) throws IOException {
return this.read(b, 0, b.length);
}
/**
* Invokes the delegate's read(byte[], int, int) method.
* @param b the buffer to read the bytes into
* @param off The start offset
* @param len The number of bytes to read
* @return the number of bytes read or -1 if the end of stream or
* the limit has been reached.
* @throws IOException if an I/O error occurs
*/
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (max>=0 && pos>=max) {
return -1;
}
long maxRead = max>=0 ? Math.min(len, max-pos) : len;
int bytesRead = in.read(b, off, (int)maxRead);
if (bytesRead==-1) {
return -1;
}
pos+=bytesRead;
return bytesRead;
}
/**
* Invokes the delegate's skip(long) method.
* @param n the number of bytes to skip
* @return the actual number of bytes skipped
* @throws IOException if an I/O error occurs
*/
@Override
public long skip(long n) throws IOException {
long toSkip = max>=0 ? Math.min(n, max-pos) : n;
long skippedBytes = in.skip(toSkip);
pos+=skippedBytes;
return skippedBytes;
}
/**
* {@inheritDoc}
*/
@Override
@SuppressForbidden("just delegating")
public int available() throws IOException {
if (max>=0 && pos>=max) {
return 0;
}
return in.available();
}
/**
* Invokes the delegate's toString() method.
* @return the delegate's toString()
*/
@Override
public String toString() {
return in.toString();
}
/**
* Invokes the delegate's close() method
* if {@link #isPropagateClose()} is true.
* @throws IOException if an I/O error occurs
*/
@Override
public void close() throws IOException {
if (propagateClose) {
in.close();
}
}
/**
* Invokes the delegate's reset() method.
* @throws IOException if an I/O error occurs
*/
@Override
public synchronized void reset() throws IOException {
in.reset();
pos = mark;
}
/**
* Invokes the delegate's mark(int) method.
* @param readlimit read ahead limit
*/
@Override
public synchronized void mark(int readlimit) {
in.mark(readlimit);
mark = pos;
}
/**
* Invokes the delegate's markSupported() method.
* @return true if mark is supported, otherwise false
*/
@Override
public boolean markSupported() {
return in.markSupported();
}
/**
* Indicates whether the {@link #close()} method
* should propagate to the underling {@link InputStream}.
*
* @return true if calling {@link #close()}
* propagates to the close() method of the
* underlying stream or false if it does not.
*/
public boolean isPropagateClose() {
return propagateClose;
}
/**
* Set whether the {@link #close()} method
* should propagate to the underling {@link InputStream}.
*
* @param propagateClose true if calling
* {@link #close()} propagates to the close()
* method of the underlying stream or
* false if it does not.
*/
public void setPropagateClose(boolean propagateClose) {
this.propagateClose = propagateClose;
}
}