| /* |
| * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/impl/io/ContentLengthInputStream.java $ |
| * $Revision: 652091 $ |
| * $Date: 2008-04-29 13:41:07 -0700 (Tue, 29 Apr 2008) $ |
| * |
| * ==================================================================== |
| * 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/>. |
| * |
| */ |
| |
| package org.apache.http.impl.io; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| import org.apache.http.io.SessionInputBuffer; |
| |
| /** |
| * Stream that cuts off after a specified number of bytes. |
| * Note that this class NEVER closes the underlying stream, even when close |
| * gets called. Instead, it will read until the "end" of its chunking on |
| * close, which allows for the seamless execution of subsequent HTTP 1.1 |
| * requests, while not requiring the client to remember to read the entire |
| * contents of the response. |
| * |
| * <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 4.0 |
| */ |
| public class ContentLengthInputStream extends InputStream { |
| |
| private static final int BUFFER_SIZE = 2048; |
| /** |
| * The maximum number of bytes that can be read from the stream. Subsequent |
| * read operations will return -1. |
| */ |
| private 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 SessionInputBuffer in = null; |
| |
| /** |
| * Creates a new length limited stream |
| * |
| * @param in The session input buffer to wrap |
| * @param contentLength The maximum number of bytes that can be read from |
| * the stream. Subsequent read operations will return -1. |
| */ |
| public ContentLengthInputStream(final SessionInputBuffer in, long contentLength) { |
| super(); |
| if (in == null) { |
| throw new IllegalArgumentException("Input stream may not be null"); |
| } |
| if (contentLength < 0) { |
| throw new IllegalArgumentException("Content length may not be negative"); |
| } |
| this.in = 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. |
| */ |
| public void close() throws IOException { |
| if (!closed) { |
| try { |
| byte buffer[] = new byte[BUFFER_SIZE]; |
| while (read(buffer) >= 0) { |
| } |
| } finally { |
| // close after above so that we don't throw an exception trying |
| // to read after closed! |
| 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() |
| */ |
| public int read() throws IOException { |
| if (closed) { |
| throw new IOException("Attempted read from closed stream."); |
| } |
| |
| if (pos >= contentLength) { |
| return -1; |
| } |
| pos++; |
| return this.in.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. |
| */ |
| public int read (byte[] b, int off, int len) throws java.io.IOException { |
| if (closed) { |
| throw new IOException("Attempted read from closed stream."); |
| } |
| |
| if (pos >= contentLength) { |
| return -1; |
| } |
| |
| if (pos + len > contentLength) { |
| len = (int) (contentLength - pos); |
| } |
| int count = this.in.read(b, off, len); |
| 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[]) |
| */ |
| 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) |
| */ |
| public long skip(long n) throws IOException { |
| if (n <= 0) { |
| return 0; |
| } |
| byte[] buffer = new byte[BUFFER_SIZE]; |
| // make sure we don't skip more bytes than are |
| // still available |
| long remaining = Math.min(n, this.contentLength - this.pos); |
| // skip and keep track of the bytes actually skipped |
| long count = 0; |
| while (remaining > 0) { |
| int l = read(buffer, 0, (int)Math.min(BUFFER_SIZE, remaining)); |
| if (l == -1) { |
| break; |
| } |
| count += l; |
| remaining -= l; |
| } |
| this.pos += count; |
| return count; |
| } |
| } |