AbstractPacketReader xref

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    1   /***
    2    *
    3    * Copyright 2004 Protique Ltd
    4    *
    5    * Licensed under the Apache License, Version 2.0 (the "License");
    6    * you may not use this file except in compliance with the License.
    7    * You may obtain a copy of the License at
    8    *
    9    * http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   *
    17   **/
    18
    19  package org.codehaus.activemq.message;
    20
    21  import java.io.ByteArrayInputStream;
    22  import java.io.DataInput;
    23  import java.io.DataInputStream;
    24  import java.io.IOException;
    25  import java.io.ObjectInputStream;
    26  import java.util.Set;
    27  import org.codehaus.activemq.util.BitArray;
    28
    29  /***
    30   * Allows instances implementing Packet interface to be deserailized
    31   *
    32   * @version $Revision: 1.12 $
    33   */
    34  public abstract class AbstractPacketReader implements PacketReader {
    35
    36      /***
    37       * @param packetType
    38       * @return true if this PacketReader can a Packet of this type
    39       */
    40      public boolean canRead(int packetType) {
    41          return this.getPacketType() == packetType;
    42      }
    43
    44      /***
    45       * pointless method - but mirrors writer
    46       *
    47       * @param dataIn
    48       * @return the String
    49       * @throws IOException
    50       */
    51      protected String readUTF(DataInput dataIn) throws IOException {
    52          return dataIn.readUTF();
    53      }
    54
    55
    56      /***
    57       * ;
    58       *
    59       * @param dataIn
    60       * @return object
    61       * @throws IOException
    62       */
    63      protected Object readObject(DataInput dataIn) throws IOException {
    64          int dataLength = dataIn.readInt();
    65          if (dataLength > 0) {
    66              byte[] data = new byte[dataLength];
    67              dataIn.readFully(data);
    68              ByteArrayInputStream bytesIn = new ByteArrayInputStream(data);
    69              ObjectInputStream objIn = new ObjectInputStream(bytesIn);
    70              try {
    71                  return objIn.readObject();
    72              }
    73              catch (ClassNotFoundException ex) {
    74                  throw new IOException(ex.getMessage());
    75              }
    76          }
    77          return null;
    78      }
    79
    80      /***
    81       * build a Packet instance from the data input stream
    82       *
    83       * @param p A Packet object
    84       * @param dataIn the data input stream to build the packet from
    85       * @throws IOException
    86       */
    87      public void buildPacket(Packet p, DataInput dataIn) throws IOException {
    88          AbstractPacket packet = (AbstractPacket)p;
    89          packet.setId(readUTF(dataIn));
    90          BitArray ba = packet.getBitArray();
    91          ba.readFromStream(dataIn);
    92          packet.setReceiptRequired(ba.get(AbstractPacket.RECEIPT_REQUIRED_INDEX));
    93          if (ba.get(AbstractPacket.BROKERS_VISITED_INDEX)){
    94              int visitedLen = dataIn.readShort();
    95              for (int i =0; i < visitedLen; i++){
    96                  packet.addBrokerVisited(dataIn.readUTF());
    97              }
    98          }
    99      }
    100
    101     /***
    102      * Deserailizes a Packet from a byte array
    103      *
    104      * @param data
    105      * @return the deserialized Packet
    106      * @throws IOException
    107      */
    108     public Packet readPacketFromByteArray(byte[] data) throws IOException {
    109         ByteArrayInputStream bytesIn = new ByteArrayInputStream(data);
    110         DataInputStream dataIn = new DataInputStream(bytesIn);
    111         Packet packet = createPacket();
    112         buildPacket(packet, dataIn);
    113         return packet;
    114     }
    115 }