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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  package org.apache.hadoop.hbase.filter;
21  
22  import org.apache.hadoop.hbase.util.Bytes;
23  
24  import java.io.DataInput;
25  import java.io.DataOutput;
26  import java.io.IOException;
27  
28  /**
29   * This comparator is for use with SingleColumnValueFilter, for filtering based on
30   * the value of a given column. Use it to test if a given substring appears
31   * in a cell value in the column. The comparison is case insensitive.
32   * <p>
33   * Only EQUAL or NOT_EQUAL tests are valid with this comparator.
34   * <p>
35   * For example:
36   * <p>
37   * <pre>
38   * SingleColumnValueFilter scvf =
39   *   new SingleColumnValueFilter("col", CompareOp.EQUAL,
40   *     new SubstringComparator("substr"));
41   * </pre>
42   */
43  public class SubstringComparator extends WritableByteArrayComparable {
44  
45    private String substr;
46  
47    /** Nullary constructor for Writable, do not use */
48    public SubstringComparator() {
49      super();
50    }
51  
52    /**
53     * Constructor
54     * @param substr the substring
55     */
56    public SubstringComparator(String substr) {
57      super(Bytes.toBytes(substr.toLowerCase()));
58      this.substr = substr.toLowerCase();
59    }
60  
61    @Override
62    public byte[] getValue() {
63      return Bytes.toBytes(substr);
64    }
65  
66    @Override
67    public int compareTo(byte[] value, int offset, int length) {
68      return Bytes.toString(value, offset, length).toLowerCase().contains(substr) ? 0
69          : 1;
70    }
71  
72    @Override
73    public void readFields(DataInput in) throws IOException {
74      String substr = in.readUTF();
75      this.value = Bytes.toBytes(substr);
76      this.substr = substr;
77    }
78  
79    @Override
80    public void write(DataOutput out) throws IOException {
81      out.writeUTF(substr);
82    }
83  
84  }