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   /*
    * Copyright 2012 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:
    *
    *   https://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.example.http.websocketx.server;
  
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.SimpleChannelInboundHandler;
  import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
  import io.netty.handler.codec.http.websocketx.WebSocketFrame;
  import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
  
  import java.util.Locale;
  
  /**
   * Echoes uppercase content of text frames.
   */
  public class WebSocketFrameHandler extends SimpleChannelInboundHandler<WebSocketFrame> {
  
      @Override
      protected void channelRead0(ChannelHandlerContext ctx, WebSocketFrame frame) throws Exception {
          // ping and pong frames already handled
  
          if (frame instanceof TextWebSocketFrame) {
              // Send the uppercase string back.
              String request = ((TextWebSocketFrame) frame).text();
              ctx.channel().writeAndFlush(new TextWebSocketFrame(request.toUpperCase(Locale.US)));
          } else {
              String message = "unsupported frame type: " + frame.getClass().getName();
              throw new UnsupportedOperationException(message);
          }
      }
  
      @Override
      public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
          if (evt instanceof WebSocketServerProtocolHandler.HandshakeComplete) {
              //Channel upgrade to websocket, remove WebSocketIndexPageHandler.
              ctx.pipeline().remove(WebSocketIndexPageHandler.class);
          } else {
              super.userEventTriggered(ctx, evt);
          }
      }
  }