FileReadStream


1   /*
2    * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3    *
4    * This file is part of Resin(R) Open Source
5    *
6    * Each copy or derived work must preserve the copyright notice and this
7    * notice unmodified.
8    *
9    * Resin Open Source is free software; you can redistribute it and/or modify
10   * it under the terms of the GNU General Public License as published by
11   * the Free Software Foundation; either version 2 of the License, or
12   * (at your option) any later version.
13   *
14   * Resin Open Source is distributed in the hope that it will be useful,
15   * but WITHOUT ANY WARRANTY; without even the implied warranty of
16   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17   * of NON-INFRINGEMENT.  See the GNU General Public License for more
18   * details.
19   *
20   * You should have received a copy of the GNU General Public License
21   * along with Resin Open Source; if not, write to the
22   *
23   *   Free Software Foundation, Inc.
24   *   59 Temple Place, Suite 330
25   *   Boston, MA 02111-1307  USA
26   *
27   * @author Scott Ferguson
28   */
29  
30  package com.caucho.vfs;
31  
32  import java.io.FileInputStream  ;
33  import java.io.IOException  ;
34  import java.io.InputStream  ;
35  
36  /**
37   * Stream encapsulating FileInputStream
38   */
39  public class FileReadStream extends StreamImpl {
40    private FileInputStream   _is;
41    
42    /**
43     * Create a new FileReadStream.
44     */
45    public FileReadStream()
46    {
47    }
48    
49    /**
50     * Create a new FileReadStream based on the java.io.* stream.
51     *
52     * @param is the underlying input stream.
53     */
54    public FileReadStream(FileInputStream   is)
55    {
56      init(is);
57    }
58    
59    /**
60     * Create a new FileReadStream based on the java.io.* stream.
61     *
62     * @param is the underlying input stream.
63     * @param path the associated Path.
64     */
65    public FileReadStream(FileInputStream   is, Path path)
66    {
67      init(is);
68      setPath(path);
69    }
70  
71    /**
72     * Initializes a VfsStream with an input/output stream pair.  Before a
73     * read, the output will be flushed to avoid deadlocks.
74     *
75     * @param is the underlying InputStream.
76     * @param os the underlying OutputStream.
77     */
78    public void init(FileInputStream   is)
79    {
80      _is = is;
81      setPath(null);
82    }
83  
84    /**
85     * Returns true if there's an associated file.
86     */
87    public boolean canSkip()
88    {
89      return _is != null;
90    }
91  
92    /**
93     * Skips bytes in the file.
94     *
95     * @param n the number of bytes to skip
96     *
97     * @return the actual bytes skipped.
98     */
99    public long skip(long n)
100     throws IOException  
101   {
102     if (_is != null)
103       return _is.skip(n);
104     else
105       return -1;
106   }
107 
108   /**
109    * Seeks based on the start.
110    */
111   public void seekStart(long offset)
112     throws IOException  
113   {
114     if (_is != null)
115       _is.getChannel().position(offset);
116   }
117 
118   /**
119    * Returns true if there's an associated file.
120    */
121   public boolean canRead()
122   {
123     return _is != null;
124   }
125 
126   /**
127    * Reads bytes from the file.
128    *
129    * @param buf a byte array receiving the data.
130    * @param offset starting index to receive data.
131    * @param length number of bytes to read.
132    *
133    * @return the number of bytes read or -1 on end of file.
134    */
135   public int read(byte []buf, int offset, int length) throws IOException  
136   {
137     if (_is == null)
138       return -1;
139 
140     int len = _is.read(buf, offset, length);
141 
142     return len;
143   }
144 
145   /**
146    * Returns the number of bytes available for reading.
147    */
148   public int getAvailable() throws IOException  
149   {
150     if (_is == null)
151       return -1;
152     else {
153       return _is.available();
154     }
155   }
156 
157   /**
158    * Closes the underlying stream.
159    */
160   public void close() throws IOException  
161   {
162     InputStream   is = _is;
163     _is = null;
164     
165     if (is != null)
166       is.close();
167   }
168 }
169
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags