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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.hadoop.hbase.io;
20  
21  import java.io.DataInput;
22  import java.io.IOException;
23  import java.io.InputStream;
24  
25  import org.apache.hadoop.classification.InterfaceAudience;
26  
27  /**
28   * An InputStream that wraps a DataInput.
29   * @see DataOutputOutputStream
30   */
31  @InterfaceAudience.Private
32  public class DataInputInputStream extends InputStream {
33  
34    private DataInput in;
35  
36    /**
37     * Construct an InputStream from the given DataInput. If 'in'
38     * is already an InputStream, simply returns it. Otherwise, wraps
39     * it in an InputStream.
40     * @param in the DataInput to wrap
41     * @return an InputStream instance that reads from 'in'
42     */
43    public static InputStream constructInputStream(DataInput in) {
44      if (in instanceof InputStream) {
45        return (InputStream)in;
46      } else {
47        return new DataInputInputStream(in);
48      }
49    }
50  
51  
52    public DataInputInputStream(DataInput in) {
53      this.in = in;
54    }
55  
56    @Override
57    public int read() throws IOException {
58      return in.readUnsignedByte();
59    }
60  }