240 lines
8.6 KiB
Java
240 lines
8.6 KiB
Java
/*
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* Copyright 2012 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the 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 io.netty.handler.codec.http;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.Unpooled;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.embedded.EmbeddedByteChannel;
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import io.netty.handler.codec.MessageToMessageCodec;
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import java.util.ArrayDeque;
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import java.util.Queue;
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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 #beginEncode(HttpMessage, 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
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* {@link #beginEncode(HttpMessage, 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 or allowed encoding in the
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* corresponding {@link HttpRequest}'s {@code "Accept-Encoding"} header,
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* {@link #beginEncode(HttpMessage, String)} should return {@code null} so that
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* no 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 #beginEncode(HttpMessage, String)} properly to make
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* this class functional. For example, refer to the source code of
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* {@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 ByteBuf}s.
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*/
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public abstract class HttpContentEncoder extends MessageToMessageCodec<HttpMessage, HttpMessage, Object, Object> {
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private final Queue<String> acceptEncodingQueue = new ArrayDeque<String>();
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private EmbeddedByteChannel 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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new Class<?>[] { HttpMessage.class },
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new Class<?>[] { HttpObject.class });
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}
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@Override
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public HttpMessage decode(ChannelHandlerContext ctx, HttpMessage msg)
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throws Exception {
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String acceptedEncoding = msg.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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return msg;
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}
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@Override
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public Object encode(ChannelHandlerContext ctx, Object msg)
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throws Exception {
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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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return msg;
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}
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if (msg instanceof HttpMessage) {
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HttpMessage m = (HttpMessage) msg;
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cleanup();
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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.getTransferEncoding().isMultiple() || m.getContent().readable();
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if (!hasContent) {
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return m;
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}
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Result result = beginEncode(m, acceptEncoding);
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if (result == null) {
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return m;
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}
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encoder = result.getContentEncoder();
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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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result.getTargetContentEncoding());
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if (m.getTransferEncoding().isSingle()) {
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ByteBuf content = m.getContent();
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// Encode the content.
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ByteBuf newContent = Unpooled.buffer();
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encode(content, newContent);
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finishEncode(newContent);
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// Replace the content.
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m.setContent(newContent);
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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(newContent.readableBytes()));
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}
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}
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} else if (msg instanceof HttpChunk) {
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HttpChunk c = (HttpChunk) msg;
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ByteBuf 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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ByteBuf newContent = Unpooled.buffer();
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encode(content, newContent);
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if (content.readable()) {
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c.setContent(newContent);
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} else {
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return null;
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}
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} else {
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ByteBuf lastProduct = Unpooled.buffer();
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finishEncode(lastProduct);
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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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return new Object[] { new DefaultHttpChunk(lastProduct), c };
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}
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}
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}
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}
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// Because HttpMessage and HttpChunk is a mutable object, we can simply forward it.
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return msg;
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}
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/**
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* Prepare to encode the HTTP message content.
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*
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* @param msg
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* the HTTP message whose content should be encoded
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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 the result of preparation, which is composed of the determined
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* target content encoding and a new {@link EncoderEmbedder} that
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* encodes the content into the target content encoding.
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* {@code null} if {@code acceptEncoding} is unsupported or rejected
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* and thus the content should be handled as-is (i.e. no encoding).
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*/
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protected abstract Result beginEncode(HttpMessage msg, String acceptEncoding) throws Exception;
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@Override
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public void afterRemove(ChannelHandlerContext ctx) throws Exception {
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cleanup();
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super.afterRemove(ctx);
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}
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@Override
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public void channelInactive(ChannelHandlerContext ctx) throws Exception {
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cleanup();
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super.channelInactive(ctx);
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}
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private void cleanup() {
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if (encoder != null) {
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// Clean-up the previous encoder if not cleaned up correctly.
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finishEncode(Unpooled.buffer());
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}
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}
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private void encode(ByteBuf in, ByteBuf out) {
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encoder.writeOutbound(in);
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fetchEncoderOutput(out);
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}
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private void finishEncode(ByteBuf out) {
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if (encoder.finish()) {
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fetchEncoderOutput(out);
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}
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encoder = null;
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}
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private void fetchEncoderOutput(ByteBuf out) {
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for (;;) {
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ByteBuf buf = encoder.readOutbound();
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if (buf == null) {
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break;
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}
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out.writeBytes(buf);
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}
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}
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public static final class Result {
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private final String targetContentEncoding;
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private final EmbeddedByteChannel contentEncoder;
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public Result(String targetContentEncoding, EmbeddedByteChannel contentEncoder) {
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if (targetContentEncoding == null) {
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throw new NullPointerException("targetContentEncoding");
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}
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if (contentEncoder == null) {
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throw new NullPointerException("contentEncoder");
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}
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this.targetContentEncoding = targetContentEncoding;
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this.contentEncoder = contentEncoder;
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}
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public String getTargetContentEncoding() {
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return targetContentEncoding;
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}
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public EmbeddedByteChannel getContentEncoder() {
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return contentEncoder;
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}
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}
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}
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