1 | /*
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2 | * Copyright 2003-2005 The Apache Software Foundation
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3 | *
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4 | * Licensed under the Apache License, Version 2.0 (the "License");
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5 | * you may not use this file except in compliance with the License.
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6 | * You may obtain a copy of the License at
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7 | *
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8 | * http://www.apache.org/licenses/LICENSE-2.0
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9 | *
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10 | * Unless required by applicable law or agreed to in writing, software
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11 | * distributed under the License is distributed on an "AS IS" BASIS,
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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13 | * See the License for the specific language governing permissions and
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14 | * limitations under the License.
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15 | *
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16 | */
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17 | package org.apache.tools.ant.util;
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18 |
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19 | import java.io.File;
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20 | import java.io.FileOutputStream;
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21 | import java.io.IOException;
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22 | import java.io.OutputStream;
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23 |
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24 | /**
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25 | * Class that delays opening the output file until the first bytes
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26 | * shall be written or the method {@link #open open} has been invoked
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27 | * explicitly.
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28 | *
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29 | * @since Ant 1.6
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30 | */
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31 | public class LazyFileOutputStream extends OutputStream {
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32 |
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33 | private FileOutputStream fos;
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34 | private File file;
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35 | private boolean append;
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36 | private boolean alwaysCreate;
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37 | private boolean opened = false;
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38 | private boolean closed = false;
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39 |
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40 | /**
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41 | * Creates a stream that will eventually write to the file with
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42 | * the given name and replace it.
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43 | */
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44 | public LazyFileOutputStream(String name) {
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45 | this(name, false);
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46 | }
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47 |
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48 | /**
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49 | * Creates a stream that will eventually write to the file with
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50 | * the given name and optionally append to instead of replacing
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51 | * it.
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52 | */
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53 | public LazyFileOutputStream(String name, boolean append) {
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54 | this(new File(name), append);
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55 | }
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56 |
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57 | /**
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58 | * Creates a stream that will eventually write to the file with
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59 | * the given name and replace it.
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60 | */
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61 | public LazyFileOutputStream(File f) {
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62 | this(f, false);
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63 | }
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64 |
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65 | /**
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66 | * Creates a stream that will eventually write to the file with
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67 | * the given name and optionally append to instead of replacing
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68 | * it.
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69 | */
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70 | public LazyFileOutputStream(File file, boolean append) {
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71 | this(file, append, false);
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72 | }
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73 |
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74 | /**
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75 | * Creates a stream that will eventually write to the file with
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76 | * the given name, optionally append to instead of replacing
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77 | * it, and optionally always create a file (even if zero length).
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78 | */
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79 | public LazyFileOutputStream(File file, boolean append,
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80 | boolean alwaysCreate) {
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81 | this.file = file;
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82 | this.append = append;
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83 | this.alwaysCreate = alwaysCreate;
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84 | }
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85 |
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86 | /**
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87 | * Explicitly open the file for writing.
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88 | *
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89 | * <p>Returns silently if the file has already been opened.</p>
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90 | */
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91 | public void open() throws IOException {
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92 | ensureOpened();
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93 | }
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94 |
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95 | public synchronized void close() throws IOException {
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96 | if (alwaysCreate && !closed) {
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97 | ensureOpened();
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98 | }
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99 | if (opened) {
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100 | fos.close();
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101 | }
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102 | closed = true;
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103 | }
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104 |
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105 | /**
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106 | * Delegates to the three-arg version.
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107 | */
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108 | public void write(byte[] b) throws IOException {
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109 | write(b, 0, b.length);
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110 | }
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111 |
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112 | //inherit doc
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113 | public synchronized void write(byte[] b, int offset, int len)
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114 | throws IOException {
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115 | ensureOpened();
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116 | fos.write(b, offset, len);
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117 | }
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118 |
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119 | //inherit doc
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120 | public synchronized void write(int b) throws IOException {
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121 | ensureOpened();
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122 | fos.write(b);
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123 | }
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124 |
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125 | private synchronized void ensureOpened() throws IOException {
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126 | if (closed) {
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127 | throw new IOException(file + " has already been closed.");
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128 | }
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129 |
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130 | if (!opened) {
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131 | fos = new FileOutputStream(file.getAbsolutePath(), append);
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132 | opened = true;
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133 | }
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134 | }
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135 | }
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