| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.iapi.util.ByteArray |
| 4 | |
| 5 | Copyright 1998, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.iapi.util; |
| 22 | |
| 23 | import java.io.ObjectOutput; |
| 24 | import java.io.ObjectInput; |
| 25 | import java.io.IOException; |
| 26 | |
| 27 | /** |
| 28 | ByteArray wraps java byte arrays (byte[]) to allow |
| 29 | byte arrays to be used as keys in hashtables. |
| 30 | |
| 31 | This is required because the equals function on |
| 32 | byte[] directly uses reference equality. |
| 33 | <P> |
| 34 | This class also allows the trio of array, offset and length |
| 35 | to be carried around as a single object. |
| 36 | */ |
| 37 | public final class ByteArray |
| 38 | { |
| 39 | |
| 40 | private byte[] array; |
| 41 | private int offset; |
| 42 | private int length; |
| 43 | |
| 44 | /** |
| 45 | Create an instance of this class that wraps ths given array. |
| 46 | This class does not make a copy of the array, it just saves |
| 47 | the reference. |
| 48 | */ |
| 49 | public ByteArray(byte[] array, int offset, int length) { |
| 50 | this.array = array; |
| 51 | this.offset = offset; |
| 52 | this.length = length; |
| 53 | } |
| 54 | |
| 55 | public ByteArray(byte[] array) { |
| 56 | this(array, 0, array.length); |
| 57 | } |
| 58 | |
| 59 | public ByteArray() |
| 60 | { |
| 61 | } |
| 62 | |
| 63 | public void setBytes(byte[] array) |
| 64 | { |
| 65 | this.array = array; |
| 66 | offset = 0; |
| 67 | length = array.length; |
| 68 | } |
| 69 | |
| 70 | public void setBytes(byte[] array, int length) |
| 71 | { |
| 72 | this.array = array; |
| 73 | this.offset = 0; |
| 74 | this.length = length; |
| 75 | } |
| 76 | |
| 77 | public void setBytes(byte[] array, int offset, int length) |
| 78 | { |
| 79 | this.array = array; |
| 80 | this.offset = offset; |
| 81 | this.length = length; |
| 82 | } |
| 83 | |
| 84 | |
| 85 | /** |
| 86 | Value equality for byte arrays. |
| 87 | */ |
| 88 | public boolean equals(Object other) { |
| 89 | if (other instanceof ByteArray) { |
| 90 | ByteArray ob = (ByteArray) other; |
| 91 | return ByteArray.equals(array, offset, length, ob.array, ob.offset, ob.length); |
| 92 | } |
| 93 | return false; |
| 94 | } |
| 95 | |
| 96 | |
| 97 | |
| 98 | /** |
| 99 | */ |
| 100 | public int hashCode() { |
| 101 | |
| 102 | byte[] larray = array; |
| 103 | |
| 104 | int hash = length; |
| 105 | for (int i = 0; i < length; i++) { |
| 106 | hash += larray[i + offset]; |
| 107 | } |
| 108 | return hash; |
| 109 | } |
| 110 | |
| 111 | public final byte[] getArray() { |
| 112 | return array; |
| 113 | } |
| 114 | public final int getOffset() { |
| 115 | return offset; |
| 116 | } |
| 117 | |
| 118 | public final int getLength() { |
| 119 | return length; |
| 120 | } |
| 121 | public final void setLength(int newLength) { |
| 122 | length = newLength; |
| 123 | } |
| 124 | |
| 125 | /** |
| 126 | * Read this object from a stream of stored objects. |
| 127 | * |
| 128 | * @param in read this. |
| 129 | * |
| 130 | * @exception IOException thrown on error |
| 131 | */ |
| 132 | public void readExternal( ObjectInput in ) throws IOException |
| 133 | { |
| 134 | int len = length = in.readInt(); |
| 135 | offset = 0; |
| 136 | array = new byte[len]; |
| 137 | |
| 138 | in.readFully(array, 0, len); |
| 139 | } |
| 140 | |
| 141 | |
| 142 | /** |
| 143 | * Write the byte array out w/o compression |
| 144 | * |
| 145 | * @param out write bytes here. |
| 146 | * |
| 147 | * @exception IOException thrown on error |
| 148 | */ |
| 149 | public void writeExternal(ObjectOutput out) throws IOException |
| 150 | { |
| 151 | out.writeInt(length); |
| 152 | out.write(array, offset, length); |
| 153 | } |
| 154 | |
| 155 | |
| 156 | |
| 157 | /** |
| 158 | Compare two byte arrays using value equality. |
| 159 | Two byte arrays are equal if their length is |
| 160 | identical and their contents are identical. |
| 161 | */ |
| 162 | private static boolean equals(byte[] a, int aOffset, int aLength, byte[] b, int bOffset, int bLength) { |
| 163 | |
| 164 | if (aLength != bLength) |
| 165 | return false; |
| 166 | |
| 167 | for (int i = 0; i < aLength; i++) { |
| 168 | if (a[i + aOffset] != b[i + bOffset]) |
| 169 | return false; |
| 170 | } |
| 171 | return true; |
| 172 | } |
| 173 | } |
| 174 | |