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1   /**
2    * Copyright 2010 The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  
21  package org.apache.hadoop.hbase.filter;
22  
23  import org.apache.hadoop.hbase.KeyValue;
24  import org.apache.hadoop.hbase.client.Get;
25  
26  import java.util.ArrayList;
27  
28  /**
29   * This filter is used to filter based on the column qualifier. It takes an
30   * operator (equal, greater, not equal, etc) and a byte [] comparator for the
31   * column qualifier portion of a key.
32   * <p>
33   * This filter can be wrapped with {@link WhileMatchFilter} and {@link SkipFilter}
34   * to add more control.
35   * <p>
36   * Multiple filters can be combined using {@link FilterList}.
37   * <p>
38   * If an already known column qualifier is looked for, use {@link Get#addColumn}
39   * directly rather than a filter.
40   */
41  public class QualifierFilter extends CompareFilter {
42  
43    /**
44     * Writable constructor, do not use.
45     */
46    public QualifierFilter() {
47    }
48  
49    /**
50     * Constructor.
51     * @param op the compare op for column qualifier matching
52     * @param qualifierComparator the comparator for column qualifier matching
53     */
54    public QualifierFilter(final CompareOp op,
55        final WritableByteArrayComparable qualifierComparator) {
56      super(op, qualifierComparator);
57    }
58  
59    @Override
60    public ReturnCode filterKeyValue(KeyValue v) {
61      int qualifierLength = v.getQualifierLength();
62      if (qualifierLength > 0) {
63        if (doCompare(this.compareOp, this.comparator, v.getBuffer(),
64            v.getQualifierOffset(), qualifierLength)) {
65          return ReturnCode.SKIP;
66        }
67      }
68      return ReturnCode.INCLUDE;
69    }
70  
71    public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
72      ArrayList arguments = CompareFilter.extractArguments(filterArguments);
73      CompareOp compareOp = (CompareOp)arguments.get(0);
74      WritableByteArrayComparable comparator = (WritableByteArrayComparable)arguments.get(1);
75      return new QualifierFilter(compareOp, comparator);
76  }
77  }