/*
* ChunkedEncoder.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.core;
import java.io.IOException;
import java.nio.ByteBuffer;
import org.simpleframework.transport.ByteWriter;
/**
* The <code>ChunkedEncoder</code> object is used to encode data in
* the chunked encoding format. A chunked producer is required when
* the length of the emitted content is unknown. It enables the HTTP
* pipeline to remain open as it is a self delimiting format. This
* is preferred over the <code>CloseEncoder</code> for HTTP/1.1 as
* it maintains the pipeline and thus the cost of creating it.
*
* @author Niall Gallagher
*
* @see org.simpleframework.http.message.ChunkedConsumer
*/
class ChunkedEncoder implements BodyEncoder {
/**
* This is the size line which is used to generate the size.
*/
private byte[] size = { '0', '0', '0', '0', '0', '0', '0', '0', '\r', '\n' };
/**
* This is the hexadecimal alphabet used to translate the size.
*/
private byte[] index = { '0', '1', '2', '3', '4', '5','6', '7', '8', '9', 'a', 'b', 'c', 'd','e', 'f' };
/**
* This is the zero length chunk sent when this is completed.
*/
private byte[] zero = { '0', '\r', '\n', '\r', '\n' };
/**
* This is the observer used to notify the selector of events.
*/
private BodyObserver observer;
/**
* This is the underlying writer used to deliver the encoded data.
*/
private ByteWriter writer;
/**
* Constructor for the <code>ChunkedEncoder</code> object. This
* is used to create a producer that can sent data in the chunked
* encoding format. Once the data is encoded in the format it is
* handed to the provided <code>ByteWriter</code> object which will
* then deliver it to the client using the underlying transport.
*
* @param observer this is the observer used to signal I/O events
* @param writer this is the writer used to deliver the content
*/
public ChunkedEncoder(BodyObserver observer, ByteWriter writer) {
this.observer = observer;
this.writer = writer;
}
/**
* This method is used to encode the provided array of bytes in
* a HTTP/1.1 complaint format and sent it to the client. Once
* the data has been encoded it is handed to the transport layer
* within the server, which may choose to buffer the data if the
* content is too small to send efficiently or if the socket is
* not write ready.
*
* @param array this is the array of bytes to send to the client
*/
public void encode(byte[] array) throws IOException {
encode(array, 0, array.length);
}
/**
* This method is used to encode the provided array of bytes in
* a HTTP/1.1 complaint format and sent it to the client. Once
* the data has been encoded it is handed to the transport layer
* within the server, which may choose to buffer the data if the
* content is too small to send efficiently or if the socket is
* not write ready.
*
* @param array this is the array of bytes to send to the client
* @param off this is the offset within the array to send from
* @param len this is the number of bytes that are to be sent
*/
public void encode(byte[] array, int off, int len) throws IOException {
ByteBuffer buffer = ByteBuffer.wrap(array, off, len);
if(len > 0) {
encode(buffer);
}
}
/**
* This method is used to encode the provided buffer of bytes in
* a HTTP/1.1 compliant format and sent it to the client. Once
* the data has been encoded it is handed to the transport layer
* within the server, which may choose to buffer the data if the
* content is too small to send efficiently or if the socket is
* not write ready.
*
* @param buffer this is the buffer of bytes to send to the client
*/
public void encode(ByteBuffer buffer) throws IOException {
int mark = buffer.position();
int size = buffer.limit();
if(mark > size) {
throw new BodyEncoderException("Buffer position greater than limit");
}
encode(buffer, 0, size - mark);
}
/**
* This method is used to encode the provided buffer of bytes in
* a HTTP/1.1 compliant format and sent it to the client. Once
* the data has been encoded it is handed to the transport layer
* within the server, which may choose to buffer the data if the
* content is too small to send efficiently or if the socket is
* not write ready.
*
* @param buffer this is the buffer of bytes to send to the client
* @param off this is the offset within the buffer to send from
* @param len this is the number of bytes that are to be sent
*/
public void encode(ByteBuffer buffer, int off, int len) throws IOException {
int pos = 7;
if(observer.isClosed()) {
throw new BodyEncoderException("Stream has been closed");
}
if(len > 0) {
for(int num = len; num > 0; num >>>= 4){
size[pos--] = index[num & 0xf];
}
try {
writer.write(size, pos + 1, 9 - pos);
writer.write(buffer, off, len);
writer.write(size, 8, 2);
} catch(Exception cause) {
if(writer != null) {
observer.error(writer);
}
throw new BodyEncoderException("Error sending response", cause);
}
}
}
/**
* This method is used to flush the contents of the buffer to
* the client. This method will block until such time as all of
* the data has been sent to the client. If at any point there
* is an error sending the content an exception is thrown.
*/
public void flush() throws IOException {
try {
if(!observer.isClosed()) {
writer.flush();
}
} catch(Exception cause) {
if(writer != null) {
observer.close(writer);
}
throw new BodyEncoderException("Error sending response", cause);
}
}
/**
* This method is used to write the zero length chunk. Writing
* the zero length chunk tells the client that the response has
* been fully sent, and the next sequence of bytes from the HTTP
* pipeline is the start of the next response. This will signal
* to the server kernel that the next request is read to read.
*/
private void finish() throws IOException {
try {
writer.write(zero);
observer.ready(writer);
} catch(Exception cause) {
if(writer != null) {
observer.close(writer);
}
throw new BodyEncoderException("Error flushing response", cause);
}
}
/**
* This is used to signal to the producer that all content has
* been written and the user no longer needs to write. This will
* either close the underlying transport or it will notify the
* monitor that the response has completed and the next request
* can begin. This ensures the content is flushed to the client.
*/
public void close() throws IOException {
if(!observer.isClosed()) {
finish();
}
}
}