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Java > Open Source Codes > org > apache > activemq > kaha > impl > index > StoreIndexReader


1 /**
2  *
3  * Licensed to the Apache Software Foundation (ASF) under one or more
4  * contributor license agreements. See the NOTICE file distributed with
5  * this work for additional information regarding copyright ownership.
6  * The ASF licenses this file to You under the Apache License, Version 2.0
7  * (the "License"); you may not use this file except in compliance with
8  * 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 package org.apache.activemq.kaha.impl.index;
19
20 import java.io.IOException JavaDoc;
21 import java.io.RandomAccessFile JavaDoc;
22
23 import org.apache.activemq.util.DataByteArrayInputStream;
24 /**
25  * Optimized Store reader
26  *
27  * @version $Revision: 1.1.1.1 $
28  */
29 class StoreIndexReader{
30     protected RandomAccessFile JavaDoc file;
31     protected DataByteArrayInputStream dataIn;
32     protected byte[] buffer=new byte[IndexItem.INDEX_SIZE];
33
34     /**
35      * Construct a Store reader
36      *
37      * @param file
38      */
39     StoreIndexReader(RandomAccessFile JavaDoc file){
40         this.file=file;
41         this.dataIn=new DataByteArrayInputStream();
42     }
43
44     protected IndexItem readItem(long offset) throws IOException JavaDoc{
45         file.seek(offset);
46         file.readFully(buffer);
47         dataIn.restart(buffer);
48         IndexItem result=new IndexItem();
49         result.setOffset(offset);
50         result.read(dataIn);
51         return result;
52     }
53     
54     void updateIndexes(IndexItem indexItem) throws IOException JavaDoc{
55         if (indexItem != null){
56             file.seek(indexItem.getOffset());
57             file.readFully(buffer,0,IndexItem.INDEXES_ONLY_SIZE);
58             dataIn.restart(buffer);
59             indexItem.readIndexes(dataIn);
60         }
61     }
62 }
63
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