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22 | 22 | |
23 | 23 | /** |
24 | 24 | * This class is a version of the one published at |
25 | - * https://code.google.com/p/jmzreader/wiki/BufferedRandomAccessFile augmented to handle unsigned | |
26 | - * bytes. The original class is published under Apache 2.0 license. Fix is marked below | |
25 | + * https://code.google.com/p/jmzreader/wiki/BufferedRandomAccessFile augmented | |
26 | + * to handle unsigned bytes. The original class is published under Apache 2.0 | |
27 | + * license. Fix is marked below | |
27 | 28 | * |
28 | - * This is an optimized version of the RandomAccessFile class as described by Nick Zhang on | |
29 | - * JavaWorld.com. The article can be found at | |
29 | + * This is an optimized version of the RandomAccessFile class as described by | |
30 | + * Nick Zhang on JavaWorld.com. The article can be found at | |
30 | 31 | * http://www.javaworld.com/javaworld/javatips/jw-javatip26.html |
31 | 32 | * |
32 | 33 | * @author jg |
33 | 34 | */ |
34 | -public class BufferedRandomAccessFile extends RandomAccessFile | |
35 | -{ | |
36 | - /** | |
37 | - * Uses a byte instead of a char buffer for efficiency reasons. | |
38 | - */ | |
39 | - private final byte buffer[]; | |
40 | - private int bufend = 0; | |
41 | - private int bufpos = 0; | |
42 | - | |
43 | - /** | |
44 | - * The position inside the actual file. | |
45 | - */ | |
46 | - private long realpos = 0; | |
47 | - | |
48 | - /** | |
49 | - * Buffer size. | |
50 | - */ | |
51 | - private final int BUFSIZE; | |
35 | +public class BufferedRandomAccessFile extends RandomAccessFile { | |
36 | + /** | |
37 | + * Uses a byte instead of a char buffer for efficiency reasons. | |
38 | + */ | |
39 | + private final byte buffer[]; | |
40 | + private int bufend = 0; | |
41 | + private int bufpos = 0; | |
52 | 42 | |
53 | - /** | |
54 | - * Creates a new instance of the BufferedRandomAccessFile. | |
55 | - * | |
56 | - * @param filename The path of the file to open. | |
57 | - * @param mode Specifies the mode to use ("r", "rw", etc.) See the BufferedLineReader | |
58 | - * documentation for more information. | |
59 | - * @param bufsize The buffer size (in bytes) to use. | |
60 | - * @throws FileNotFoundException If the mode is "r" but the given string does not denote an | |
61 | - * existing regular file, or if the mode begins with "rw" but the given string does not denote | |
62 | - * an existing, writable regular file and a new regular file of that name cannot be created, or | |
63 | - * if some other error occurs while opening or creating the file. | |
64 | - */ | |
65 | - public BufferedRandomAccessFile(String filename, String mode, int bufsize) | |
66 | - throws FileNotFoundException | |
67 | - { | |
68 | - super(filename, mode); | |
69 | - BUFSIZE = bufsize; | |
70 | - buffer = new byte[BUFSIZE]; | |
71 | - } | |
43 | + /** | |
44 | + * The position inside the actual file. | |
45 | + */ | |
46 | + private long realpos = 0; | |
72 | 47 | |
73 | - /** | |
74 | - * Creates a new instance of the BufferedRandomAccessFile. | |
75 | - * | |
76 | - * @param file The file to open. | |
77 | - * @param mode Specifies the mode to use ("r", "rw", etc.) See the BufferedLineReader | |
78 | - * documentation for more information. | |
79 | - * @throws FileNotFoundException If the mode is "r" but the given file path does not denote an | |
80 | - * existing regular file, or if the mode begins with "rw" but the given file path does not denote | |
81 | - * an existing, writable regular file and a new regular file of that name cannot be created, or | |
82 | - * if some other error occurs while opening or creating the file. | |
83 | - */ | |
84 | - public BufferedRandomAccessFile(File file, String mode) | |
85 | - throws FileNotFoundException | |
86 | - { | |
87 | - super(file, mode); | |
88 | - BUFSIZE = 8192; | |
89 | - buffer = new byte[BUFSIZE]; | |
90 | - } | |
48 | + /** | |
49 | + * Buffer size. | |
50 | + */ | |
51 | + private final int BUFSIZE; | |
91 | 52 | |
92 | - /** | |
93 | - * {@inheritDoc} | |
94 | - */ | |
95 | - @Override | |
96 | - public final int read() throws IOException | |
97 | - { | |
98 | - if (bufpos >= bufend && fillBuffer() < 0) | |
99 | - { | |
100 | - return -1; | |
101 | - } | |
102 | - if (bufend == 0) | |
103 | - { | |
104 | - return -1; | |
105 | - } | |
106 | - // FIX to handle unsigned bytes | |
107 | - return (buffer[bufpos++] + 256) & 0xFF; | |
108 | - // End of fix | |
109 | - } | |
53 | + /** | |
54 | + * Creates a new instance of the BufferedRandomAccessFile. | |
55 | + * | |
56 | + * @param filename | |
57 | + * The path of the file to open. | |
58 | + * @param mode | |
59 | + * Specifies the mode to use ("r", "rw", etc.) See the | |
60 | + * BufferedLineReader documentation for more information. | |
61 | + * @param bufsize | |
62 | + * The buffer size (in bytes) to use. | |
63 | + * @throws FileNotFoundException | |
64 | + * If the mode is "r" but the given string does not denote an | |
65 | + * existing regular file, or if the mode begins with "rw" but the | |
66 | + * given string does not denote an existing, writable regular file | |
67 | + * and a new regular file of that name cannot be created, or if some | |
68 | + * other error occurs while opening or creating the file. | |
69 | + */ | |
70 | + public BufferedRandomAccessFile(String filename, String mode, int bufsize) throws FileNotFoundException { | |
71 | + super(filename, mode); | |
72 | + BUFSIZE = bufsize; | |
73 | + buffer = new byte[BUFSIZE]; | |
74 | + } | |
110 | 75 | |
111 | - /** | |
112 | - * Reads the next BUFSIZE bytes into the internal buffer. | |
113 | - * | |
114 | - * @return The total number of bytes read into the buffer, or -1 if there is no more data | |
115 | - * because the end of the file has been reached. | |
116 | - * @throws IOException If the first byte cannot be read for any reason other than end of file, | |
117 | - * or if the random access file has been closed, or if some other I/O error occurs. | |
118 | - */ | |
119 | - private int fillBuffer() throws IOException | |
120 | - { | |
121 | - int n = super.read(buffer, 0, BUFSIZE); | |
76 | + /** | |
77 | + * Creates a new instance of the BufferedRandomAccessFile. | |
78 | + * | |
79 | + * @param file | |
80 | + * The file to open. | |
81 | + * @param mode | |
82 | + * Specifies the mode to use ("r", "rw", etc.) See the | |
83 | + * BufferedLineReader documentation for more information. | |
84 | + * @throws FileNotFoundException | |
85 | + * If the mode is "r" but the given file path does not denote an | |
86 | + * existing regular file, or if the mode begins with "rw" but the | |
87 | + * given file path does not denote an existing, writable regular | |
88 | + * file and a new regular file of that name cannot be created, or if | |
89 | + * some other error occurs while opening or creating the file. | |
90 | + */ | |
91 | + public BufferedRandomAccessFile(File file, String mode) throws FileNotFoundException { | |
92 | + super(file, mode); | |
93 | + BUFSIZE = 512; | |
94 | + buffer = new byte[BUFSIZE]; | |
95 | + } | |
122 | 96 | |
123 | - if (n >= 0) | |
124 | - { | |
125 | - realpos += n; | |
126 | - bufend = n; | |
127 | - bufpos = 0; | |
128 | - } | |
129 | - return n; | |
130 | - } | |
97 | + /** | |
98 | + * {@inheritDoc} | |
99 | + */ | |
100 | + @Override | |
101 | + public final int read() throws IOException { | |
102 | + if (bufpos >= bufend && fillBuffer() < 0) { | |
103 | + return -1; | |
104 | + } | |
105 | + if (bufend == 0) { | |
106 | + return -1; | |
107 | + } | |
108 | + // FIX to handle unsigned bytes | |
109 | + return (buffer[bufpos++] + 256) & 0xFF; | |
110 | + // End of fix | |
111 | + } | |
131 | 112 | |
132 | - /** | |
133 | - * Clears the local buffer. | |
134 | - * | |
135 | - * @throws IOException If an I/O error occurs. | |
136 | - */ | |
137 | - private void invalidate() throws IOException | |
138 | - { | |
139 | - bufend = 0; | |
140 | - bufpos = 0; | |
141 | - realpos = super.getFilePointer(); | |
142 | - } | |
113 | + /** | |
114 | + * Reads the next BUFSIZE bytes into the internal buffer. | |
115 | + * | |
116 | + * @return The total number of bytes read into the buffer, or -1 if there is no | |
117 | + * more data because the end of the file has been reached. | |
118 | + * @throws IOException | |
119 | + * If the first byte cannot be read for any reason other than end of | |
120 | + * file, or if the random access file has been closed, or if some | |
121 | + * other I/O error occurs. | |
122 | + */ | |
123 | + private int fillBuffer() throws IOException { | |
124 | + int n = super.read(buffer, 0, BUFSIZE); | |
143 | 125 | |
144 | - /** | |
145 | - * {@inheritDoc} | |
146 | - */ | |
147 | - @Override | |
148 | - public int read(byte b[]) throws IOException { | |
149 | - return this.read(b, 0, b.length); | |
150 | - } | |
151 | - | |
152 | - /** | |
153 | - * {@inheritDoc} | |
154 | - */ | |
155 | - @Override | |
156 | - public int read(byte b[], int off, int len) throws IOException | |
157 | - { | |
158 | - int leftover = bufend - bufpos; | |
159 | - if (len <= leftover) | |
160 | - { | |
161 | - System.arraycopy(buffer, bufpos, b, off, len); | |
162 | - bufpos += len; | |
163 | - return len; | |
164 | - } | |
165 | - System.arraycopy(buffer, bufpos, b, off, leftover); | |
166 | - bufpos += leftover; | |
167 | - if (fillBuffer() > 0) | |
168 | - { | |
169 | - int bytesRead = read(b, off + leftover, len - leftover); | |
170 | - if (bytesRead > 0) | |
171 | - { | |
172 | - leftover += bytesRead; | |
173 | - } | |
174 | - } | |
175 | - return leftover > 0 ? leftover : -1; | |
176 | - } | |
126 | + if (n >= 0) { | |
127 | + realpos += n; | |
128 | + bufend = n; | |
129 | + bufpos = 0; | |
130 | + } | |
131 | + return n; | |
132 | + } | |
177 | 133 | |
178 | - /** | |
179 | - * {@inheritDoc} | |
180 | - */ | |
181 | - @Override | |
182 | - public long getFilePointer() throws IOException | |
183 | - { | |
184 | - return realpos - bufend + bufpos; | |
185 | - } | |
134 | + /** | |
135 | + * Clears the local buffer. | |
136 | + * | |
137 | + * @throws IOException | |
138 | + * If an I/O error occurs. | |
139 | + */ | |
140 | + private void invalidate() throws IOException { | |
141 | + bufend = 0; | |
142 | + bufpos = 0; | |
143 | + realpos = super.getFilePointer(); | |
144 | + } | |
186 | 145 | |
187 | - /** | |
188 | - * {@inheritDoc} | |
189 | - */ | |
190 | - @Override | |
191 | - public void seek(long pos) throws IOException | |
192 | - { | |
193 | - int n = (int) (realpos - pos); | |
194 | - if (n >= 0 && n <= bufend) | |
195 | - { | |
196 | - bufpos = bufend - n; | |
197 | - } | |
198 | - else | |
199 | - { | |
200 | - super.seek(pos); | |
201 | - invalidate(); | |
202 | - } | |
203 | - } | |
146 | + /** | |
147 | + * {@inheritDoc} | |
148 | + */ | |
149 | + @Override | |
150 | + public int read(byte b[]) throws IOException { | |
151 | + return this.read(b, 0, b.length); | |
152 | + } | |
153 | + | |
154 | + /** | |
155 | + * {@inheritDoc} | |
156 | + */ | |
157 | + @Override | |
158 | + public int read(byte b[], int off, int len) throws IOException { | |
159 | + int leftover = bufend - bufpos; | |
160 | + if (len <= leftover) { | |
161 | + System.arraycopy(buffer, bufpos, b, off, len); | |
162 | + bufpos += len; | |
163 | + return len; | |
164 | + } | |
165 | + System.arraycopy(buffer, bufpos, b, off, leftover); | |
166 | + bufpos += leftover; | |
167 | + if (fillBuffer() > 0) { | |
168 | + int bytesRead = read(b, off + leftover, len - leftover); | |
169 | + if (bytesRead > 0) { | |
170 | + leftover += bytesRead; | |
171 | + } | |
172 | + } | |
173 | + return leftover > 0 ? leftover : -1; | |
174 | + } | |
175 | + | |
176 | + /** | |
177 | + * {@inheritDoc} | |
178 | + */ | |
179 | + @Override | |
180 | + public long getFilePointer() throws IOException { | |
181 | + return realpos - bufend + bufpos; | |
182 | + } | |
183 | + | |
184 | + /** | |
185 | + * {@inheritDoc} | |
186 | + */ | |
187 | + @Override | |
188 | + public void seek(long pos) throws IOException { | |
189 | + int n = (int) (realpos - pos); | |
190 | + if (n >= 0 && n <= bufend) { | |
191 | + bufpos = bufend - n; | |
192 | + } else { | |
193 | + super.seek(pos); | |
194 | + invalidate(); | |
195 | + } | |
196 | + } | |
204 | 197 | } |
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