/*
* Copyright 2011 The Netty Project
*
* The Netty Project 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.jboss.netty.handler.codec.http;
import java.util.Queue;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.handler.codec.embedder.EncoderEmbedder;
import org.jboss.netty.util.internal.QueueFactory;
/**
* Encodes the content of the outbound {@link HttpResponse} and {@link HttpChunk}.
* The original content is replaced with the new content encoded by the
* {@link EncoderEmbedder}, which is created by {@link #newContentEncoder(String)}.
* Once encoding is finished, the value of the <tt>'Content-Encoding'</tt> header
* is set to the target content encoding, as returned by {@link #getTargetContentEncoding(String)}.
* Also, the <tt>'Content-Length'</tt> header is updated to the length of the
* encoded content. If there is no supported encoding in the
* corresponding {@link HttpRequest}'s {@code "Accept-Encoding"} header,
* {@link #newContentEncoder(String)} should return {@code null} so that no
* encoding occurs (i.e. pass-through).
* <p>
* Please note that this is an abstract class. You have to extend this class
* and implement {@link #newContentEncoder(String)} and {@link #getTargetContentEncoding(String)}
* properly to make this class functional. For example, refer to the source
* code of {@link HttpContentCompressor}.
* <p>
* This handler must be placed after {@link HttpMessageEncoder} in the pipeline
* so that this handler can intercept HTTP responses before {@link HttpMessageEncoder}
* converts them into {@link ChannelBuffer}s.
*/
public abstract class HttpContentEncoder extends SimpleChannelHandler {
private final Queue<String> acceptEncodingQueue = QueueFactory.createQueue(String.class);
private volatile EncoderEmbedder<ChannelBuffer> encoder;
/**
* Creates a new instance.
*/
protected HttpContentEncoder() {
super();
}
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e)
throws Exception {
Object msg = e.getMessage();
if (!(msg instanceof HttpMessage)) {
ctx.sendUpstream(e);
return;
}
HttpMessage m = (HttpMessage) msg;
String acceptedEncoding = m.getHeader(HttpHeaders.Names.ACCEPT_ENCODING);
if (acceptedEncoding == null) {
acceptedEncoding = HttpHeaders.Values.IDENTITY;
}
boolean offered = acceptEncodingQueue.offer(acceptedEncoding);
assert offered;
ctx.sendUpstream(e);
}
@Override
public void writeRequested(ChannelHandlerContext ctx, MessageEvent e)
throws Exception {
Object msg = e.getMessage();
if (msg instanceof HttpResponse && ((HttpResponse) msg).getStatus().getCode() == 100) {
// 100-continue response must be passed through.
ctx.sendDownstream(e);
} else if (msg instanceof HttpMessage) {
HttpMessage m = (HttpMessage) msg;
encoder = null;
String contentEncoding = m.getHeader(HttpHeaders.Names.CONTENT_ENCODING);
if (contentEncoding != null &&
!HttpHeaders.Values.IDENTITY.equalsIgnoreCase(contentEncoding)) {
// Content-Encoding is set already and it is not 'identity'.
ctx.sendDownstream(e);
} else {
// Determine the content encoding.
String acceptEncoding = acceptEncodingQueue.poll();
if (acceptEncoding == null) {
throw new IllegalStateException("cannot send more responses than requests");
}
boolean hasContent = m.isChunked() || m.getContent().readable();
if (hasContent && (encoder = newContentEncoder(acceptEncoding)) != null) {
// Encode the content and remove or replace the existing headers
// so that the message looks like a decoded message.
m.setHeader(
HttpHeaders.Names.CONTENT_ENCODING,
getTargetContentEncoding(acceptEncoding));
if (!m.isChunked()) {
ChannelBuffer content = m.getContent();
// Encode the content.
content = ChannelBuffers.wrappedBuffer(
encode(content), finishEncode());
// Replace the content.
m.setContent(content);
if (m.containsHeader(HttpHeaders.Names.CONTENT_LENGTH)) {
m.setHeader(
HttpHeaders.Names.CONTENT_LENGTH,
Integer.toString(content.readableBytes()));
}
}
}
// Because HttpMessage is a mutable object, we can simply forward the write request.
ctx.sendDownstream(e);
}
} else if (msg instanceof HttpChunk) {
HttpChunk c = (HttpChunk) msg;
ChannelBuffer content = c.getContent();
// Encode the chunk if necessary.
if (encoder != null) {
if (!c.isLast()) {
content = encode(content);
if (content.readable()) {
c.setContent(content);
ctx.sendDownstream(e);
}
} else {
ChannelBuffer lastProduct = finishEncode();
// Generate an additional chunk if the decoder produced
// the last product on closure,
if (lastProduct.readable()) {
Channels.write(
ctx, Channels.succeededFuture(e.getChannel()), new DefaultHttpChunk(lastProduct), e.getRemoteAddress());
}
// Emit the last chunk.
ctx.sendDownstream(e);
}
} else {
ctx.sendDownstream(e);
}
} else {
ctx.sendDownstream(e);
}
}
/**
* Returns a new {@link EncoderEmbedder} that encodes the HTTP message
* content.
*
* @param acceptEncoding
* the value of the {@code "Accept-Encoding"} header
*
* @return a new {@link EncoderEmbedder} if there is a supported encoding
* in {@code acceptEncoding}. {@code null} otherwise.
*/
protected abstract EncoderEmbedder<ChannelBuffer> newContentEncoder(String acceptEncoding) throws Exception;
/**
* Returns the expected content encoding of the encoded content.
*
* @param acceptEncoding the value of the {@code "Accept-Encoding"} header
* @return the expected content encoding of the new content
*/
protected abstract String getTargetContentEncoding(String acceptEncoding) throws Exception;
private ChannelBuffer encode(ChannelBuffer buf) {
encoder.offer(buf);
return ChannelBuffers.wrappedBuffer(encoder.pollAll(new ChannelBuffer[encoder.size()]));
}
private ChannelBuffer finishEncode() {
ChannelBuffer result;
if (encoder.finish()) {
result = ChannelBuffers.wrappedBuffer(encoder.pollAll(new ChannelBuffer[encoder.size()]));
} else {
result = ChannelBuffers.EMPTY_BUFFER;
}
encoder = null;
return result;
}
}