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Java > Open Source Codes > org > columba > ristretto > io > AsyncInputStream


1 /* ***** BEGIN LICENSE BLOCK *****
2  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
3  *
4  * The contents of this file are subject to the Mozilla Public License Version
5  * 1.1 (the "License"); you may not use this file except in compliance with
6  * the License. You may obtain a copy of the License at
7  * http://www.mozilla.org/MPL/
8  *
9  * Software distributed under the License is distributed on an "AS IS" basis,
10  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
11  * for the specific language governing rights and limitations under the
12  * License.
13  *
14  * The Original Code is Ristretto Mail API.
15  *
16  * The Initial Developers of the Original Code are
17  * Timo Stich and Frederik Dietz.
18  * Portions created by the Initial Developers are Copyright (C) 2004
19  * All Rights Reserved.
20  *
21  * Contributor(s):
22  *
23  * Alternatively, the contents of this file may be used under the terms of
24  * either the GNU General Public License Version 2 or later (the "GPL"), or
25  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
26  * in which case the provisions of the GPL or the LGPL are applicable instead
27  * of those above. If you wish to allow use of your version of this file only
28  * under the terms of either the GPL or the LGPL, and not to allow others to
29  * use your version of this file under the terms of the MPL, indicate your
30  * decision by deleting the provisions above and replace them with the notice
31  * and other provisions required by the GPL or the LGPL. If you do not delete
32  * the provisions above, a recipient may use your version of this file under
33  * the terms of any one of the MPL, the GPL or the LGPL.
34  *
35  * ***** END LICENSE BLOCK ***** */
36 package org.columba.ristretto.io;
37
38 import java.io.FilterInputStream JavaDoc;
39 import java.io.IOException JavaDoc;
40 import java.io.InputStream JavaDoc;
41
42 import org.columba.ristretto.concurrency.Semaphore;
43
44 /**
45  * InputStream for asynchronous download. It works
46  * together with the IMAPDownloadThread to allow for
47  * a non-blocking fetch operation on the IMAP server.
48  *
49  *
50  * @author tstich
51  *
52  */
53 public class AsyncInputStream extends FilterInputStream JavaDoc {
54     
55     private Semaphore semaphore;
56     private IOException JavaDoc exception;
57     private int size;
58     private int read;
59     
60     /**
61      * Constructs the AsyncSourceInputStream.java.
62      *
63      * @param source
64      * @param size the total Size of the data
65      */
66     public AsyncInputStream(InputStream JavaDoc source, int size) {
67         super(source);
68         semaphore = new Semaphore();
69         this.size = size;
70         read = 0;
71     }
72     
73     
74     /**
75      * @see java.io.InputStream#read()
76      */
77     public int read() throws IOException JavaDoc {
78         if( read < size ) {
79         
80             semaphore.acquire();
81             if( exception != null ) throw exception;
82             if( read < size ) {
83                 read++;
84             
85                 return super.read();
86             } else {
87                 return -1;
88             }
89         } else {
90             return -1;
91         }
92     }
93     
94     
95     
96     /**
97      * An exception occured while downloading.
98      *
99      * @param e
100      */
101     public void exceptionOccured( IOException JavaDoc e ) {
102         exception = e;
103     }
104     
105     /**
106      * The available data has grown to the given size.
107      *
108      * @param size
109      */
110     public void grow(int size) {
111         semaphore.release(size);
112     }
113     
114     /**
115      * @see java.io.InputStream#read(byte[], int, int)
116      */
117     public int read(byte[] arg0, int arg1, int arg2) throws IOException JavaDoc {
118         int next;
119         for( int i=0; i<arg2; i++) {
120             next = read();
121             if( next == -1 ) {
122                 if( i == 0 ) {
123                     return -1;
124                 } else {
125                     return i;
126                 }
127             }
128             arg0[arg1+i] = (byte) next;
129         }
130         return arg2;
131     }
132     /**
133      * @see java.io.InputStream#available()
134      */
135     public int available() throws IOException JavaDoc {
136         return size - read;
137     }
138     /**
139      * @return Returns the size.
140      */
141     public int getSize() {
142         return size;
143     }
144     /**
145      * @param size The size to set.
146      */
147     public void setSize(int size) {
148         this.size = size;
149     }
150 }
151
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