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1 /*
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2 * @(#)SeekableByteArrayOutputStream.java 1.0 2010-12-27
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3 *
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4 * Copyright © 2010 Werner Randelshofer, Immensee, Switzerland.
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5 * All rights reserved.
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6 *
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7 * You may not use, copy or modify this file, except in compliance with the
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8 * license agreement you entered into with Werner Randelshofer.
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9 * For details see accompanying license terms.
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10 */
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11
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12 package ca.randelshofer;
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13
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14 import java.io.ByteArrayOutputStream;
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15 import java.io.IOException;
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16 import java.io.OutputStream;
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17 import java.util.Arrays;
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18 import static java.lang.Math.*;
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19 /**
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20 * {@code SeekableByteArrayOutputStream}.
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21 *
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22 * @author Werner Randelshofer
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23 * @version 1.0 2010-12-27 Created.
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24 */
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25 public class SeekableByteArrayOutputStream extends ByteArrayOutputStream {
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26
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27 /**
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28 * The current stream position.
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29 */
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30 private int pos;
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31
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32 /**
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33 * Creates a new byte array output stream. The buffer capacity is
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34 * initially 32 bytes, though its size increases if necessary.
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35 */
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36 public SeekableByteArrayOutputStream() {
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37 this(32);
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38 }
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39
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40 /**
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41 * Creates a new byte array output stream, with a buffer capacity of
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42 * the specified size, in bytes.
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43 *
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44 * @param size the initial size.
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45 * @exception IllegalArgumentException if size is negative.
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46 */
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47 public SeekableByteArrayOutputStream(int size) {
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48 if (size < 0) {
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49 throw new IllegalArgumentException("Negative initial size: "
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50 + size);
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51 }
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52 buf = new byte[size];
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53 }
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54
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55 /**
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56 * Writes the specified byte to this byte array output stream.
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57 *
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58 * @param b the byte to be written.
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59 */
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60 @Override
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61 public synchronized void write(int b) {
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62 int newcount = max(pos + 1, count);
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63 if (newcount > buf.length) {
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64 buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
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65 }
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66 buf[pos++] = (byte)b;
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67 count = newcount;
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68 }
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69
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70 /**
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71 * Writes <code>len</code> bytes from the specified byte array
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72 * starting at offset <code>off</code> to this byte array output stream.
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73 *
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74 * @param b the data.
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75 * @param off the start offset in the data.
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76 * @param len the number of bytes to write.
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77 */
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78 @Override
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79 public synchronized void write(byte b[], int off, int len) {
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80 if ((off < 0) || (off > b.length) || (len < 0) ||
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81 ((off + len) > b.length) || ((off + len) < 0)) {
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82 throw new IndexOutOfBoundsException();
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83 } else if (len == 0) {
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84 return;
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85 }
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86 int newcount = max(pos+len,count);
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87 if (newcount > buf.length) {
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88 buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
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89 }
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90 System.arraycopy(b, off, buf, pos, len);
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91 pos+=len;
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92 count = newcount;
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93 }
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94
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95 /**
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96 * Resets the <code>count</code> field of this byte array output
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97 * stream to zero, so that all currently accumulated output in the
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98 * output stream is discarded. The output stream can be used again,
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99 * reusing the already allocated buffer space.
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100 *
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101 * @see java.io.ByteArrayInputStream#count
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102 */
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103 @Override
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104 public synchronized void reset() {
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105 count = 0;
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106 pos=0;
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107 }
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108
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109 /**
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110 * Sets the current stream position to the desired location. The
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111 * next read will occur at this location. The bit offset is set
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112 * to 0.
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113 *
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114 * <p> An <code>IndexOutOfBoundsException</code> will be thrown if
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115 * <code>pos</code> is smaller than the flushed position (as
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116 * returned by <code>getflushedPosition</code>).
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117 *
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118 * <p> It is legal to seek past the end of the file; an
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119 * <code>EOFException</code> will be thrown only if a read is
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120 * performed.
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121 *
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122 * @param pos a <code>long</code> containing the desired file
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123 * pointer position.
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124 *
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125 * @exception IndexOutOfBoundsException if <code>pos</code> is smaller
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126 * than the flushed position.
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127 * @exception IOException if any other I/O error occurs.
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128 */
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129 public void seek(long pos) throws IOException {
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130 this.pos = (int)pos;
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131 }
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132
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133 /**
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134 * Returns the current byte position of the stream. The next write
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135 * will take place starting at this offset.
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136 *
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137 * @return a long containing the position of the stream.
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138 *
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139 * @exception IOException if an I/O error occurs.
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140 */
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141 public long getStreamPosition() throws IOException {
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142 return pos;
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143 }
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144
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145 /** Writes the contents of the byte array into the specified output
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146 * stream.
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147 * @param out
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148 */
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149 public void toOutputStream(OutputStream out) throws IOException {
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150 out.write(buf, 0, count);
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151 }
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152
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153 }
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