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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  /**
27   * This filter is used to filter based on the column qualifier. It takes an
28   * operator (equal, greater, not equal, etc) and a byte [] comparator for the
29   * column qualifier portion of a key.
30   * <p>
31   * This filter can be wrapped with {@link WhileMatchFilter} and {@link SkipFilter}
32   * to add more control.
33   * <p>
34   * Multiple filters can be combined using {@link FilterList}.
35   * <p>
36   * If an already known column qualifier is looked for, use {@link Get#addColumn}
37   * directly rather than a filter.
38   */
39  public class QualifierFilter extends CompareFilter {
40  
41    /**
42     * Writable constructor, do not use.
43     */
44    public QualifierFilter() {
45    }
46  
47    /**
48     * Constructor.
49     * @param qualifierCompareOp the compare op for column qualifier matching
50     * @param qualifierComparator the comparator for column qualifier matching
51     */
52    public QualifierFilter(final CompareOp qualifierCompareOp,
53        final WritableByteArrayComparable qualifierComparator) {
54      super(qualifierCompareOp, qualifierComparator);
55    }
56  
57    @Override
58    public ReturnCode filterKeyValue(KeyValue v) {
59      int qualifierLength = v.getQualifierLength();
60      if (qualifierLength > 0) {
61        if (doCompare(this.compareOp, this.comparator, v.getBuffer(),
62            v.getQualifierOffset(), qualifierLength)) {
63          return ReturnCode.SKIP;
64        }
65      }
66      return ReturnCode.INCLUDE;
67    }
68  }