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/*
* FixedLengthConsumer.java February 2007
*
* Copyright (C) 2001, Niall Gallagher <niallg@users.sf.net>
*
* Licensed 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.simpleframework.http.message;
import java.io.IOException;
import org.simpleframework.common.buffer.Allocator;
import org.simpleframework.common.buffer.Buffer;
/**
* The <code>FixedLengthConsumer</code> object reads a fixed number of
* bytes from a cursor. This is typically used when the Content-Length
* header is used as the body delimiter. In order to determine when
* the full body has been consumed this counts the bytes read. Once
* all the bytes have been read any overflow will be reset. All of the
* bytes read are appended to the internal buffer so they can be read.
*
* @author Niall Gallagher
*/
public class FixedLengthConsumer extends UpdateConsumer {
/**
* This is the allocator used to allocate the buffer used.
*/
private Allocator allocator;
/**
* This is the internal buffer used to accumulate the body.
*/
private Buffer buffer;
/**
* This is the number of bytes to be consumed from the cursor.
*/
private long limit;
/**
* Constructor for the <code>FixedLengthConsumer</code> object. This
* is used to create a consumer that reads a fixed number of bytes
* from a cursor and accumulates those bytes in an internal buffer
* so that it can be read at a later stage.
*
* @param allocator this is used to allocate the internal buffer
* @param limit this is the number of bytes that are to be read
*/
public FixedLengthConsumer(Allocator allocator, long limit) {
this.allocator = allocator;
this.limit = limit;
}
/**
* This is used to acquire the body that has been consumed. This
* will return a body which can be used to read the content of
* the message, also if the request is multipart upload then all
* of the parts are provided as <code>Attachment</code> objects.
* Each part can then be read as an individual message.
*
* @return the body that has been consumed by this instance
*/
public Body getBody() {
return new BufferBody(buffer);
}
/**
* This method is used to append the contents of the array to the
* internal buffer. The appended bytes can be acquired from the
* internal buffer using an <code>InputStream</code>, or the text
* of the appended bytes can be acquired by encoding the bytes.
*
* @param array this is the array of bytes to be appended
* @param off this is the start offset in the array to read from
* @param len this is the number of bytes to write to the buffer
*/
private void append(byte[] array, int off, int len) throws IOException {
if(buffer == null) {
buffer = allocator.allocate(limit);
}
buffer.append(array, off, len);
}
/**
* This is used to process the bytes that have been read from the
* cursor. This will count the number of bytes read, once all of
* the bytes that form the body have been read this returns the
* number of bytes that represent the overflow.
*
* @param array this is a chunk read from the cursor
* @param off this is the offset within the array the chunk starts
* @param count this is the number of bytes within the array
*
* @return this returns the number of bytes overflow that is read
*/
@Override
protected int update(byte[] array, int off, int count) throws IOException {
int mark = (int)limit;
if(count >= limit) {
append(array, off, mark);
finished = true;
limit = 0;
return count - mark;
}
if(count > 0) {
append(array, off, count);
limit -= count;
}
return 0;
}
}
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