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Java > Open Source Codes > com > go > trove > io > FileByteData


1 /* ====================================================================
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52
53 package com.go.trove.io;
54
55 import java.io.OutputStream JavaDoc;
56 import java.io.File JavaDoc;
57 import java.io.RandomAccessFile JavaDoc;
58 import java.io.IOException JavaDoc;
59
60 /******************************************************************************
61  * A ByteData implementation that reads the contents of a file.
62  *
63  * @author Brian S O'Neill
64  * @version
65  * <!--$$Revision:--> 19 <!-- $-->, <!--$$JustDate:--> 00/12/06 <!-- $-->
66  */

67 public class FileByteData implements ByteData {
68     private static final Object JavaDoc NULL = new Object JavaDoc();
69     
70     private File JavaDoc mFile;
71
72     // Thread-local reference to a RandomAccessFile.
73
private ThreadLocal JavaDoc mRAF = new ThreadLocal JavaDoc();
74
75     public FileByteData(File JavaDoc file) {
76         mFile = file;
77         // Open here so that if file isn't found, error is logged earlier.
78
open();
79     }
80
81     public long getByteCount() throws IOException JavaDoc {
82         // Keep file open to ensure that length doesn't change between call to
83
// getByteCount and writeTo.
84

85         RandomAccessFile JavaDoc raf = open();
86         if (raf == null) {
87             return 0;
88         }
89         else {
90             return raf.length();
91         }
92     }
93
94     public void writeTo(OutputStream JavaDoc out) throws IOException JavaDoc {
95         RandomAccessFile JavaDoc raf = open();
96         if (raf == null) {
97             return;
98         }
99
100         try {
101             long length = raf.length();
102             int bufSize;
103             if (length > 4000) {
104                 bufSize = 4000;
105             }
106             else {
107                 bufSize = (int)length;
108             }
109             
110             byte[] inputBuffer = new byte[bufSize];
111
112             raf.seek(0);
113         
114             int readAmount;
115             while ((readAmount = raf.read(inputBuffer, 0, bufSize)) > 0) {
116                 out.write(inputBuffer, 0, readAmount);
117             }
118         }
119         finally {
120             try {
121                 finalize();
122             }
123             catch (IOException JavaDoc e) {
124             }
125         }
126     }
127
128     public void reset() throws IOException JavaDoc {
129         Object JavaDoc obj = mRAF.get();
130         try {
131             if (obj instanceof RandomAccessFile JavaDoc) {
132                 ((RandomAccessFile JavaDoc)obj).close();
133             }
134         }
135         finally {
136             mRAF.set(null);
137         }
138     }
139
140     protected final void finalize() throws IOException JavaDoc {
141         reset();
142     }
143
144     private RandomAccessFile JavaDoc open() {
145         Object JavaDoc obj = mRAF.get();
146         if (obj instanceof RandomAccessFile JavaDoc) {
147             return (RandomAccessFile JavaDoc)obj;
148         }
149         else if (obj == NULL) {
150             return null;
151         }
152
153         RandomAccessFile JavaDoc raf = null;
154
155         try {
156             raf = new RandomAccessFile JavaDoc(mFile, "r");
157             mRAF.set(raf);
158         }
159         catch (IOException JavaDoc e) {
160             mRAF.set(NULL);
161             Thread JavaDoc t = Thread.currentThread();
162             t.getThreadGroup().uncaughtException(t, e);
163         }
164
165         return raf;
166     }
167 }
168
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