200 lines
7.8 KiB
Java
200 lines
7.8 KiB
Java
/*
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* Copyright 2009 Red Hat, Inc.
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*
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* Red Hat licenses this file to you under the Apache License, version 2.0
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* (the "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package org.jboss.netty.handler.codec.http;
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import java.util.Queue;
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import org.jboss.netty.buffer.ChannelBuffer;
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import org.jboss.netty.buffer.ChannelBuffers;
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import org.jboss.netty.channel.ChannelHandlerContext;
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import org.jboss.netty.channel.Channels;
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import org.jboss.netty.channel.MessageEvent;
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import org.jboss.netty.channel.SimpleChannelHandler;
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import org.jboss.netty.handler.codec.embedder.EncoderEmbedder;
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import org.jboss.netty.util.internal.LinkedTransferQueue;
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/**
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* Encodes the content of the outbound {@link HttpResponse} and {@link HttpChunk}.
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* The original content is replaced with the new content encoded by the
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* {@link EncoderEmbedder}, which is created by {@link #newContentEncoder(String)}.
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* Once encoding is finished, the value of the <tt>'Content-Encoding'</tt> header
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* is set to the target content encoding, as returned by {@link #getTargetContentEncoding(String)}.
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* Also, the <tt>'Content-Length'</tt> header is updated to the length of the
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* encoded content. If there is no supported encoding in the
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* corresponding {@link HttpRequest}'s {@code "Accept-Encoding"} header,
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* {@link #newContentEncoder(String)} should return {@code null} so that no
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* encoding occurs (i.e. pass-through).
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* <p>
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* Please note that this is an abstract class. You have to extend this class
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* and implement {@link #newContentEncoder(String)} and {@link #getTargetContentEncoding(String)}
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* properly to make this class functional. For example, refer to the source
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* code of {@link HttpContentCompressor}.
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* <p>
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* This handler must be placed after {@link HttpMessageEncoder} in the pipeline
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* so that this handler can intercept HTTP responses before {@link HttpMessageEncoder}
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* converts them into {@link ChannelBuffer}s.
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*
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* @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
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* @author <a href="http://gleamynode.net/">Trustin Lee</a>
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* @version $Rev$, $Date$
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*/
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public abstract class HttpContentEncoder extends SimpleChannelHandler {
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private final Queue<String> acceptEncodingQueue = new LinkedTransferQueue<String>();
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private volatile EncoderEmbedder<ChannelBuffer> encoder;
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/**
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* Creates a new instance.
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*/
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protected HttpContentEncoder() {
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super();
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}
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@Override
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public void messageReceived(ChannelHandlerContext ctx, MessageEvent e)
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throws Exception {
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Object msg = e.getMessage();
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if (!(msg instanceof HttpMessage)) {
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ctx.sendUpstream(e);
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return;
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}
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HttpMessage m = (HttpMessage) msg;
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String acceptedEncoding = m.getHeader(HttpHeaders.Names.ACCEPT_ENCODING);
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if (acceptedEncoding == null) {
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acceptedEncoding = HttpHeaders.Values.IDENTITY;
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}
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boolean offered = acceptEncodingQueue.offer(acceptedEncoding);
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assert offered;
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ctx.sendUpstream(e);
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}
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@Override
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public void writeRequested(ChannelHandlerContext ctx, MessageEvent e)
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throws Exception {
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Object msg = e.getMessage();
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if (msg instanceof HttpResponse && ((HttpResponse) msg).getStatus().getCode() == 100) {
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// 100-continue response must be passed through.
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ctx.sendDownstream(e);
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} else if (msg instanceof HttpMessage) {
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HttpMessage m = (HttpMessage) msg;
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encoder = null;
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// Determine the content encoding.
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String acceptEncoding = acceptEncodingQueue.poll();
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if (acceptEncoding == null) {
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throw new IllegalStateException("cannot send more responses than requests");
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}
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boolean hasContent = m.isChunked() || m.getContent().readable();
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if (hasContent && (encoder = newContentEncoder(acceptEncoding)) != null) {
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// Encode the content and remove or replace the existing headers
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// so that the message looks like a decoded message.
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m.setHeader(
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HttpHeaders.Names.CONTENT_ENCODING,
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getTargetContentEncoding(acceptEncoding));
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if (!m.isChunked()) {
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ChannelBuffer content = m.getContent();
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// Encode the content.
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content = ChannelBuffers.wrappedBuffer(
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encode(content), finishEncode());
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// Replace the content.
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m.setContent(content);
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if (m.containsHeader(HttpHeaders.Names.CONTENT_LENGTH)) {
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m.setHeader(
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HttpHeaders.Names.CONTENT_LENGTH,
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Integer.toString(content.readableBytes()));
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}
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}
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}
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// Because HttpMessage is a mutable object, we can simply forward the write request.
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ctx.sendDownstream(e);
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} else if (msg instanceof HttpChunk) {
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HttpChunk c = (HttpChunk) msg;
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ChannelBuffer content = c.getContent();
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// Encode the chunk if necessary.
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if (encoder != null) {
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if (!c.isLast()) {
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content = encode(content);
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if (content.readable()) {
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c.setContent(content);
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ctx.sendDownstream(e);
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}
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} else {
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ChannelBuffer lastProduct = finishEncode();
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// Generate an additional chunk if the decoder produced
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// the last product on closure,
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if (lastProduct.readable()) {
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Channels.write(
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ctx, Channels.succeededFuture(e.getChannel()), new DefaultHttpChunk(lastProduct), e.getRemoteAddress());
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}
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// Emit the last chunk.
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ctx.sendDownstream(e);
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}
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} else {
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ctx.sendDownstream(e);
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}
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} else {
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ctx.sendDownstream(e);
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}
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}
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/**
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* Returns a new {@link EncoderEmbedder} that encodes the HTTP message
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* content.
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*
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* @param acceptEncoding
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* the value of the {@code "Accept-Encoding"} header
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*
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* @return a new {@link EncoderEmbedder} if there is a supported encoding
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* in {@code acceptEncoding}. {@code null} otherwise.
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*/
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protected abstract EncoderEmbedder<ChannelBuffer> newContentEncoder(String acceptEncoding) throws Exception;
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/**
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* Returns the expected content encoding of the encoded content.
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*
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* @param acceptEncoding the value of the {@code "Accept-Encoding"} header
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* @return the expected content encoding of the new content
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*/
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protected abstract String getTargetContentEncoding(String acceptEncoding) throws Exception;
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private ChannelBuffer encode(ChannelBuffer buf) {
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encoder.offer(buf);
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return ChannelBuffers.wrappedBuffer(encoder.pollAll(new ChannelBuffer[encoder.size()]));
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}
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private ChannelBuffer finishEncode() {
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ChannelBuffer result;
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if (encoder.finish()) {
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result = ChannelBuffers.wrappedBuffer(encoder.pollAll(new ChannelBuffer[encoder.size()]));
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} else {
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result = ChannelBuffers.EMPTY_BUFFER;
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}
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encoder = null;
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return result;
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}
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}
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