Java tutorial
/* * Copyright 2014 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 io.netty.handler.codec.http.websocketx.extensions.compression; import io.netty.handler.codec.compression.ZlibCodecFactory; import io.netty.handler.codec.http.websocketx.extensions.WebSocketClientExtension; import io.netty.handler.codec.http.websocketx.extensions.WebSocketClientExtensionHandshaker; import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionData; import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionDecoder; import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionEncoder; import io.netty.handler.codec.http.websocketx.extensions.WebSocketExtensionFilterProvider; import java.util.HashMap; import java.util.Iterator; import java.util.Map.Entry; import static io.netty.handler.codec.http.websocketx.extensions.compression.PerMessageDeflateServerExtensionHandshaker.*; import static io.netty.util.internal.ObjectUtil.*; /** * <a href="http://tools.ietf.org/html/draft-ietf-hybi-permessage-compression-18">permessage-deflate</a> * handshake implementation. */ public final class PerMessageDeflateClientExtensionHandshaker implements WebSocketClientExtensionHandshaker { private final int compressionLevel; private final boolean allowClientWindowSize; private final int requestedServerWindowSize; private final boolean allowClientNoContext; private final boolean requestedServerNoContext; private final WebSocketExtensionFilterProvider extensionFilterProvider; /** * Constructor with default configuration. */ public PerMessageDeflateClientExtensionHandshaker() { this(6, ZlibCodecFactory.isSupportingWindowSizeAndMemLevel(), MAX_WINDOW_SIZE, false, false); } /** * Constructor with custom configuration. * * @param compressionLevel * Compression level between 0 and 9 (default is 6). * @param allowClientWindowSize * allows WebSocket server to customize the client inflater window size * (default is false). * @param requestedServerWindowSize * indicates the requested sever window size to use if server inflater is customizable. * @param allowClientNoContext * allows WebSocket server to activate client_no_context_takeover * (default is false). * @param requestedServerNoContext * indicates if client needs to activate server_no_context_takeover * if server is compatible with (default is false). */ public PerMessageDeflateClientExtensionHandshaker(int compressionLevel, boolean allowClientWindowSize, int requestedServerWindowSize, boolean allowClientNoContext, boolean requestedServerNoContext) { this(compressionLevel, allowClientWindowSize, requestedServerWindowSize, allowClientNoContext, requestedServerNoContext, WebSocketExtensionFilterProvider.DEFAULT); } /** * Constructor with custom configuration. * * @param compressionLevel * Compression level between 0 and 9 (default is 6). * @param allowClientWindowSize * allows WebSocket server to customize the client inflater window size * (default is false). * @param requestedServerWindowSize * indicates the requested sever window size to use if server inflater is customizable. * @param allowClientNoContext * allows WebSocket server to activate client_no_context_takeover * (default is false). * @param requestedServerNoContext * indicates if client needs to activate server_no_context_takeover * if server is compatible with (default is false). * @param extensionFilterProvider * provides client extension filters for per message deflate encoder and decoder. */ public PerMessageDeflateClientExtensionHandshaker(int compressionLevel, boolean allowClientWindowSize, int requestedServerWindowSize, boolean allowClientNoContext, boolean requestedServerNoContext, WebSocketExtensionFilterProvider extensionFilterProvider) { if (requestedServerWindowSize > MAX_WINDOW_SIZE || requestedServerWindowSize < MIN_WINDOW_SIZE) { throw new IllegalArgumentException( "requestedServerWindowSize: " + requestedServerWindowSize + " (expected: 8-15)"); } if (compressionLevel < 0 || compressionLevel > 9) { throw new IllegalArgumentException("compressionLevel: " + compressionLevel + " (expected: 0-9)"); } this.compressionLevel = compressionLevel; this.allowClientWindowSize = allowClientWindowSize; this.requestedServerWindowSize = requestedServerWindowSize; this.allowClientNoContext = allowClientNoContext; this.requestedServerNoContext = requestedServerNoContext; this.extensionFilterProvider = checkNotNull(extensionFilterProvider, "extensionFilterProvider"); } @Override public WebSocketExtensionData newRequestData() { HashMap<String, String> parameters = new HashMap<String, String>(4); if (requestedServerWindowSize != MAX_WINDOW_SIZE) { parameters.put(SERVER_NO_CONTEXT, null); } if (allowClientNoContext) { parameters.put(CLIENT_NO_CONTEXT, null); } if (requestedServerWindowSize != MAX_WINDOW_SIZE) { parameters.put(SERVER_MAX_WINDOW, Integer.toString(requestedServerWindowSize)); } if (allowClientWindowSize) { parameters.put(CLIENT_MAX_WINDOW, null); } return new WebSocketExtensionData(PERMESSAGE_DEFLATE_EXTENSION, parameters); } @Override public WebSocketClientExtension handshakeExtension(WebSocketExtensionData extensionData) { if (!PERMESSAGE_DEFLATE_EXTENSION.equals(extensionData.name())) { return null; } boolean succeed = true; int clientWindowSize = MAX_WINDOW_SIZE; int serverWindowSize = MAX_WINDOW_SIZE; boolean serverNoContext = false; boolean clientNoContext = false; Iterator<Entry<String, String>> parametersIterator = extensionData.parameters().entrySet().iterator(); while (succeed && parametersIterator.hasNext()) { Entry<String, String> parameter = parametersIterator.next(); if (CLIENT_MAX_WINDOW.equalsIgnoreCase(parameter.getKey())) { // allowed client_window_size_bits if (allowClientWindowSize) { clientWindowSize = Integer.parseInt(parameter.getValue()); } else { succeed = false; } } else if (SERVER_MAX_WINDOW.equalsIgnoreCase(parameter.getKey())) { // acknowledged server_window_size_bits serverWindowSize = Integer.parseInt(parameter.getValue()); if (clientWindowSize > MAX_WINDOW_SIZE || clientWindowSize < MIN_WINDOW_SIZE) { succeed = false; } } else if (CLIENT_NO_CONTEXT.equalsIgnoreCase(parameter.getKey())) { // allowed client_no_context_takeover if (allowClientNoContext) { clientNoContext = true; } else { succeed = false; } } else if (SERVER_NO_CONTEXT.equalsIgnoreCase(parameter.getKey())) { // acknowledged server_no_context_takeover if (requestedServerNoContext) { serverNoContext = true; } else { succeed = false; } } else { // unknown parameter succeed = false; } } if ((requestedServerNoContext && !serverNoContext) || requestedServerWindowSize != serverWindowSize) { succeed = false; } if (succeed) { return new PermessageDeflateExtension(serverNoContext, serverWindowSize, clientNoContext, clientWindowSize, extensionFilterProvider); } else { return null; } } private final class PermessageDeflateExtension implements WebSocketClientExtension { private final boolean serverNoContext; private final int serverWindowSize; private final boolean clientNoContext; private final int clientWindowSize; private final WebSocketExtensionFilterProvider extensionFilterProvider; @Override public int rsv() { return RSV1; } PermessageDeflateExtension(boolean serverNoContext, int serverWindowSize, boolean clientNoContext, int clientWindowSize, WebSocketExtensionFilterProvider extensionFilterProvider) { this.serverNoContext = serverNoContext; this.serverWindowSize = serverWindowSize; this.clientNoContext = clientNoContext; this.clientWindowSize = clientWindowSize; this.extensionFilterProvider = extensionFilterProvider; } @Override public WebSocketExtensionEncoder newExtensionEncoder() { return new PerMessageDeflateEncoder(compressionLevel, clientWindowSize, clientNoContext, extensionFilterProvider.encoderFilter()); } @Override public WebSocketExtensionDecoder newExtensionDecoder() { return new PerMessageDeflateDecoder(serverNoContext, extensionFilterProvider.decoderFilter()); } } }