java/src/main/com/google/appengine/api/datastore/Blob.java

   1 /*
   2  * Copyright 2007 Google Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
   5  * use this file except in compliance with the License. You may obtain a copy of
   6  * the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  12  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  13  * License for the specific language governing permissions and limitations under
  14  * the License.
  15  */
  16 package com.google.appengine.api.datastore;
  17
  18 import java.io.Serializable;
  19 import java.util.Arrays;
  20
  21 /**
  22  * {@code Blob} contains an array of bytes.  This byte array can be no bigger
  23  * than 1MB.  To store files, particularly files larger than this 1MB limit,
  24  * look at the Blobstore API.
  25  *
  26  */
  27 public final class Blob implements Serializable {
  28
  29   private static final long serialVersionUID = 6210713401925622518L;
  30
  31   private byte[] bytes;
  32
  33   /**
  34    * Construct a new {@code Blob} with the specified bytes.  Since
  35    * {@code Blobs} can be quite large we do not perform a defensive copy of the
  36    * provided byte array.  It is the programmer's responsibility to avoid
  37    * making changes to this array once the {@code Blob} has been constructed.
  38    */
  39   public Blob(byte[] bytes) {
  40     this.bytes = bytes;
  41   }
  42
  43   /**
  44    * This constructor exists for frameworks (e.g. Google Web Toolkit)
  45    * that require it for serialization purposes.  It should not be
  46    * called explicitly.
  47    */
  48   @SuppressWarnings("unused")
  49   private Blob(){
  50   }
  51
  52   /**
  53    * Return the bytes stored in this {@code Blob}.
  54    */
  55   public byte[] getBytes() {
  56     return bytes;
  57   }
  58
  59   @Override
  60   public int hashCode() {
  61     return Arrays.hashCode(bytes);
  62   }
  63
  64   /**
  65    * Two {@code Blob} objects are considered equal if their contained
  66    * bytes match exactly.
  67    */
  68   @Override
  69   public boolean equals(Object object) {
  70     if (object instanceof Blob) {
  71       Blob key = (Blob) object;
  72       return Arrays.equals(bytes, key.bytes);
  73     }
  74     return false;
  75   }
  76
  77   /**
  78    * Simply prints the number of bytes contained in this {@code Blob}.
  79    */
  80   @Override
  81   public String toString() {
  82     return "<Blob: " + bytes.length + " bytes>";
  83   }
  84 }