Key.java
上传用户:quxuerui
上传日期:2018-01-08
资源大小:41811k
文件大小:5k
- /**
- *
- * Copyright (c) 2005, European Commission project OneLab under contract 034819 (http://www.one-lab.org)
- * All rights reserved.
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * - Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the distribution.
- * - Neither the name of the University Catholique de Louvain - UCL
- * nor the names of its contributors may be used to endorse or
- * promote products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
- /**
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements. See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership. The ASF 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
- *
- * http://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 org.apache.hadoop.util.bloom;
- import java.io.DataInput;
- import java.io.DataOutput;
- import java.io.IOException;
- import org.apache.hadoop.io.WritableComparable;
- /**
- * The general behavior of a key that must be stored in a filter.
- *
- * @see Filter The general behavior of a filter
- */
- public class Key implements WritableComparable<Key> {
- /** Byte value of key */
- byte[] bytes;
-
- /**
- * The weight associated to <i>this</i> key.
- * <p>
- * <b>Invariant</b>: if it is not specified, each instance of
- * <code>Key</code> will have a default weight of 1.0
- */
- double weight;
- /** default constructor - use with readFields */
- public Key() {}
- /**
- * Constructor.
- * <p>
- * Builds a key with a default weight.
- * @param value The byte value of <i>this</i> key.
- */
- public Key(byte[] value) {
- this(value, 1.0);
- }
- /**
- * Constructor.
- * <p>
- * Builds a key with a specified weight.
- * @param value The value of <i>this</i> key.
- * @param weight The weight associated to <i>this</i> key.
- */
- public Key(byte[] value, double weight) {
- set(value, weight);
- }
- /**
- * @param value
- * @param weight
- */
- public void set(byte[] value, double weight) {
- if (value == null) {
- throw new IllegalArgumentException("value can not be null");
- }
- this.bytes = value;
- this.weight = weight;
- }
-
- /** @return byte[] The value of <i>this</i> key. */
- public byte[] getBytes() {
- return this.bytes;
- }
- /** @return Returns the weight associated to <i>this</i> key. */
- public double getWeight() {
- return weight;
- }
- /**
- * Increments the weight of <i>this</i> key with a specified value.
- * @param weight The increment.
- */
- public void incrementWeight(double weight) {
- this.weight += weight;
- }
- /** Increments the weight of <i>this</i> key by one. */
- public void incrementWeight() {
- this.weight++;
- }
- @Override
- public boolean equals(Object o) {
- if (!(o instanceof Key)) {
- return false;
- }
- return this.compareTo((Key)o) == 0;
- }
-
- @Override
- public int hashCode() {
- int result = 0;
- for (int i = 0; i < bytes.length; i++) {
- result ^= Byte.valueOf(bytes[i]).hashCode();
- }
- result ^= Double.valueOf(weight).hashCode();
- return result;
- }
- // Writable
- public void write(DataOutput out) throws IOException {
- out.writeInt(bytes.length);
- out.write(bytes);
- out.writeDouble(weight);
- }
-
- public void readFields(DataInput in) throws IOException {
- this.bytes = new byte[in.readInt()];
- in.readFully(this.bytes);
- weight = in.readDouble();
- }
-
- // Comparable
-
- public int compareTo(Key other) {
- int result = this.bytes.length - other.getBytes().length;
- for (int i = 0; result == 0 && i < bytes.length; i++) {
- result = this.bytes[i] - other.bytes[i];
- }
-
- if (result == 0) {
- result = Double.valueOf(this.weight - other.weight).intValue();
- }
- return result;
- }
- }