1 /*
2 * Copyright (c) 2003, Henri Yandell
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or
6 * without modification, are permitted provided that the
7 * following conditions are met:
8 *
9 * + Redistributions of source code must retain the above copyright notice,
10 * this list of conditions and the following disclaimer.
11 *
12 * + Redistributions in binary form must reproduce the above copyright notice,
13 * this list of conditions and the following disclaimer in the documentation
14 * and/or other materials provided with the distribution.
15 *
16 * + Neither the name of Genjava-Core nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32 package com.generationjava.io;
33
34 import java.io.File;
35
36 import java.util.LinkedList;
37 import java.util.Iterator;
38
39 public class FilePoller implements Runnable {
40
41 static public void main(String[] strs) {
42 pollFile(strs[0]);
43 }
44
45 static public void pollFile(String filename) {
46 File file = new File(filename);
47 FilePoller fp = new FilePoller();
48 fp.addListener( new PollListener() {
49 public void fileChanged(FileEvent fe) {
50 System.err.println("File changed. ");
51 }
52 } );
53 fp.setFile(file);
54 fp.setDelay(1L);
55 Thread t = new Thread(fp);
56 t.start();
57 }
58
59 private File file;
60 private long delay;
61 private StringBuffer buffer;
62
63 private LinkedList listeners;
64
65 public void setFile(File file) {
66 this.file = file;
67 }
68
69 public void setDelay(long delay) {
70 this.delay = delay;
71 }
72
73 public void addListener(PollListener listener) {
74 if(listeners == null) {
75 listeners = new LinkedList();
76 }
77 listeners.add(listener);
78 }
79
80 private void notifyListeners() {
81 if(listeners == null) {
82 return;
83 }
84 FileEvent fe = new FileEvent(this);
85 Iterator iterator = listeners.iterator();
86 while(iterator.hasNext()) {
87 PollListener pl = (PollListener)iterator.next();
88 pl.fileChanged(fe);
89 }
90 }
91
92 public void run() {
93 long length = file.length();
94 long lastMod = file.lastModified();
95 // try {
96 while(true) {
97 if( (length != file.length()) ||
98 (lastMod != file.lastModified())
99 )
100 {
101 notifyListeners();
102 }
103 length = file.length();
104 lastMod = file.lastModified();
105 try {
106 Thread.sleep(this.delay);
107 } catch(InterruptedException ie) {
108 }
109 }
110 // } catch(IOException ioe) {
111 // ioe.printStackTrace();
112 // }
113 }
114
115 private void append(char ch) {
116 if(buffer == null) {
117 buffer = new StringBuffer();
118 }
119 buffer.append(ch);
120 }
121
122 public String getData() {
123 return buffer.toString();
124 }
125
126 public void clearData() {
127 buffer = null;
128 }
129
130 }