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   /*
    * 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:
    *
    * 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.http2;
  
  import static io.netty.util.internal.ObjectUtil.checkNotNull;
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.Unpooled;
  import io.netty.handler.codec.http.QueryStringDecoder;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.List;
  
  /**
   * Utility methods used by the example client and server.
   */
  public final class Http2ExampleUtil {
  
      /**
       * Response header sent in response to the http->http2 cleartext upgrade request.
       */
      public static final String UPGRADE_RESPONSE_HEADER = "http-to-http2-upgrade";
  
      /**
       * Size of the block to be read from the input stream.
       */
      private static final int BLOCK_SIZE = 1024;
  
      private Http2ExampleUtil() { }
  
      /**
       * @param string the string to be converted to an integer.
       * @param defaultValue the default value
       * @return the integer value of a string or the default value, if the string is either null or empty.
       */
      public static int toInt(String string, int defaultValue) {
          if (string != null && !string.isEmpty()) {
              return Integer.parseInt(string);
          }
          return defaultValue;
      }
  
      /**
       * Reads an InputStream into a byte array.
       * @param input the InputStream.
       * @return a byte array representation of the InputStream.
       * @throws IOException if an I/O exception of some sort happens while reading the InputStream.
       */
      public static ByteBuf toByteBuf(InputStream input) throws IOException {
          ByteBuf buf = Unpooled.buffer();
          int n = 0;
          do {
              n = buf.writeBytes(input, BLOCK_SIZE);
          } while (n > 0);
          return buf;
      }
  
      /**
       * @param query the decoder of query string
       * @param key the key to lookup
       * @return the first occurrence of that key in the string parameters
       */
      public static String firstValue(QueryStringDecoder query, String key) {
          checkNotNull(query, "Query can't be null!");
          List<String> values = query.parameters().get(key);
          if (values == null || values.isEmpty()) {
              return null;
          }
          return values.get(0);
      }
  }