Current File : //proc/thread-self/root/home/waritko/yacy/source/net/yacy/server/http/ContentLengthInputStream.java
/*
* ====================================================================
*
* 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
/*
* This file was imported from apache http client 3.1 library and modified
* to work for the YaCy http server when htto client library use was migrated
* to apache http components 4.0
* by Michael Christen, 20.09.2010
*/
package net.yacy.server.http;
import java.io.IOException;
import java.io.InputStream;
/**
* Cuts the wrapped InputStream off after a specified number of bytes.
*
* <p>Implementation note: Choices abound. One approach would pass
* through the {@link InputStream#mark} and {@link InputStream#reset} calls to
* the underlying stream. That's tricky, though, because you then have to
* start duplicating the work of keeping track of how much a reset rewinds.
* Further, you have to watch out for the "readLimit", and since the semantics
* for the readLimit leave room for differing implementations, you might get
* into a lot of trouble.</p>
*
* <p>Alternatively, you could make this class extend {@link java.io.BufferedInputStream}
* and then use the protected members of that class to avoid duplicated effort.
* That solution has the side effect of adding yet another possible layer of
* buffering.</p>
*
* <p>Then, there is the simple choice, which this takes - simply don't
* support {@link InputStream#mark} and {@link InputStream#reset}. That choice
* has the added benefit of keeping this class very simple.</p>
*
* @author Ortwin Glueck
* @author Eric Johnson
* @author <a href="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
* @since 2.0
*/
public class ContentLengthInputStream extends InputStream {
/**
* The maximum number of bytes that can be read from the stream. Subsequent
* read operations will return -1.
*/
private final long contentLength;
/** The current position */
private long pos = 0;
/** True if the stream is closed. */
private boolean closed = false;
/**
* Wrapped input stream that all calls are delegated to.
*/
private InputStream wrappedStream = null;
/**
* Creates a new length limited stream
*
* @param in The stream to wrap
* @param contentLength The maximum number of bytes that can be read from
* the stream. Subsequent read operations will return -1.
*
* @since 3.0
*/
public ContentLengthInputStream(InputStream in, long contentLength) {
super();
this.wrappedStream = in;
this.contentLength = contentLength;
}
/**
* <p>Reads until the end of the known length of content.</p>
*
* <p>Does not close the underlying socket input, but instead leaves it
* primed to parse the next response.</p>
* @throws IOException If an IO problem occurs.
*/
@Override
public synchronized void close() throws IOException {
if (!this.closed) {
try {
ChunkedInputStream.exhaustInputStream(this);
} finally {
// close after above so that we don't throw an exception trying
// to read after closed!
this.closed = true;
}
}
}
/**
* Read the next byte from the stream
* @return The next byte or -1 if the end of stream has been reached.
* @throws IOException If an IO problem occurs
* @see java.io.InputStream#read()
*/
@Override
public int read() throws IOException {
if (this.closed) {
throw new IOException("Attempted read from closed stream.");
}
if (this.pos >= this.contentLength) {
return -1;
}
this.pos++;
return this.wrappedStream.read();
}
/**
* Does standard {@link InputStream#read(byte[], int, int)} behavior, but
* also notifies the watcher when the contents have been consumed.
*
* @param b The byte array to fill.
* @param off Start filling at this position.
* @param len The number of bytes to attempt to read.
* @return The number of bytes read, or -1 if the end of content has been
* reached.
*
* @throws java.io.IOException Should an error occur on the wrapped stream.
*/
@Override
public int read (byte[] b, int off, int len) throws java.io.IOException {
if (this.closed) {
throw new IOException("Attempted read from closed stream.");
}
if (this.pos >= this.contentLength) {
return -1;
}
if (this.pos + len > this.contentLength) {
len = (int) (this.contentLength - this.pos);
}
int count = this.wrappedStream.read(b, off, len);
this.pos += count;
return count;
}
/**
* Read more bytes from the stream.
* @param b The byte array to put the new data in.
* @return The number of bytes read into the buffer.
* @throws IOException If an IO problem occurs
* @see java.io.InputStream#read(byte[])
*/
@Override
public int read(byte[] b) throws IOException {
return read(b, 0, b.length);
}
/**
* Skips and discards a number of bytes from the input stream.
* @param n The number of bytes to skip.
* @return The actual number of bytes skipped. <= 0 if no bytes
* are skipped.
* @throws IOException If an error occurs while skipping bytes.
* @see InputStream#skip(long)
*/
@Override
public long skip(long n) throws IOException {
// make sure we don't skip more bytes than are
// still available
long length = Math.min(n, this.contentLength - this.pos);
// skip and keep track of the bytes actually skipped
length = this.wrappedStream.skip(length);
// only add the skipped bytes to the current position
// if bytes were actually skipped
if (length > 0) {
this.pos += length;
}
return length;
}
@Override
public int available() throws IOException {
if (this.closed) {
return 0;
}
int avail = this.wrappedStream.available();
if (this.pos + avail > this.contentLength ) {
avail = (int)(this.contentLength - this.pos);
}
return avail;
}
}
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