URLFile


1   /*
2   
3      Derby - Class org.apache.derby.impl.io.URLFile
4   
5      Licensed to the Apache Software Foundation (ASF) under one or more
6      contributor license agreements.  See the NOTICE file distributed with
7      this work for additional information regarding copyright ownership.
8      The ASF licenses this file to you under the Apache License, Version 2.0
9      (the "License"); you may not use this file except in compliance with
10     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  
22  package org.apache.derby.impl.io;
23  
24  import org.apache.derby.io.StorageFile;
25  import org.apache.derby.io.StorageRandomAccessFile;
26  
27  import org.apache.derby.iapi.services.sanity.SanityManager;
28  
29  import java.io.InputStream  ;
30  import java.io.OutputStream  ;
31  import java.io.IOException  ;
32  import java.io.FileNotFoundException  ;
33  
34  import java.net.URL  ;
35  
36  /**
37   * This class provides a class path based implementation of the StorageFile interface. It is used by the
38   * database engine to access persistent data and transaction logs under the classpath subsubprotocol.
39   */
40  class URLFile extends InputStreamFile
41  {
42  
43      private final URLStorageFactory storageFactory;
44  
45      URLFile( URLStorageFactory storageFactory, String   path)
46      {
47          super( storageFactory, path);
48          this.storageFactory = storageFactory;
49      }
50  
51      URLFile( URLStorageFactory storageFactory, String   parent, String   name)
52      {
53          super( storageFactory, parent, name);
54          this.storageFactory = storageFactory;
55      }
56  
57      URLFile( URLFile dir, String   name)
58      {
59          super( dir,name);
60          this.storageFactory = dir.storageFactory;
61      }
62  
63      private URLFile( URLStorageFactory storageFactory, String   child, int pathLen)
64      {
65          super( storageFactory, child, pathLen);
66          this.storageFactory = storageFactory;
67      }
68  
69      /**
70       * Tests whether the named file exists.
71       *
72       * @return <b>true</b> if the named file exists, <b>false</b> if not.
73       */
74      public boolean exists()
75      {
76          try
77          {
78              InputStream   is = getInputStream();
79              if( is == null)
80                  return false;
81              is.close();
82              return true;
83          }
84          catch( IOException   ioe){ return false;}
85      } // end of exists
86  
87      /**
88       * Get the parent of this file.
89       *
90       * @param pathLen the length of the parent's path name.
91       */
92      StorageFile getParentDir( int pathLen)
93      {
94          return new URLFile( storageFactory, path, pathLen);
95      }
96      
97      /**
98       * Creates an input stream from a file name.
99       *
100      * @return an input stream suitable for reading from the file.
101      *
102      * @exception FileNotFoundException if the file is not found.
103      */
104     public InputStream   getInputStream( ) throws FileNotFoundException  
105     {
106         try
107         {
108             URL   url = new URL  ( path);
109             return url.openStream();
110         }
111         catch( IOException   ioe){ throw new java.io.FileNotFoundException  (path);}
112     } // end of getInputStream
113 }
114
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