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10344
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1 /*
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2 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 */
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23
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24 import java.io.DataInputStream;
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25 import java.io.File;
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26 import java.io.FileInputStream;
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27 import java.io.FileWriter;
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28 import java.io.IOException;
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29 import java.io.PrintWriter;
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30 import javax.tools.JavaCompiler;
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31 import javax.tools.ToolProvider;
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32
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33 /**
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34 * A class loader that generates new classes.
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35 * The generated classes are made by first emitting java sources with nested
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36 * static classes, these are then compiled and the class files are read back.
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37 * Some efforts are made to make the class instances unique and of not insignificant
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38 * size.
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39 */
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40 public class GeneratedClassLoader extends ClassLoader {
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41 /**
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42 * Holds a pair of class bytecodes and class name (for use with defineClass).
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43 */
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44 private static class GeneratedClass {
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45 public byte[] bytes;
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46 public String name;
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47 public GeneratedClass(byte[] bytes, String name) {
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48 this.bytes = bytes; this.name = name;
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49 }
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50 }
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51
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52 /**
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53 * Used to uniquely name every class generated.
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54 */
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55 private static int count = 0;
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56 /**
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57 * Used to enable/disable keeping the class files and java sources for
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58 * the generated classes.
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59 */
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60 private static boolean deleteFiles = Boolean.parseBoolean(
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61 System.getProperty("GeneratedClassLoader.deleteFiles", "true"));
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62
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63 private static String bigstr =
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64 "Lorem ipsum dolor sit amet, consectetur adipiscing elit. "
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65 + "In facilisis scelerisque vehicula. Donec congue nisi a "
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66 + "leo posuere placerat lobortis felis ultrices. Pellentesque "
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67 + "habitant morbi tristique senectus et netus et malesuada "
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68 + "fames ac turpis egestas. Nam tristique velit at felis "
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69 + "iaculis at tempor sem vestibulum. Sed adipiscing lectus "
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70 + "non mi molestie sagittis. Morbi eu purus urna. Nam tempor "
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71 + "tristique massa eget semper. Mauris cursus, nulla et ornare "
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72 + "vehicula, leo dolor scelerisque metus, sit amet rutrum erat "
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73 + "sapien quis dui. Nullam eleifend risus et velit accumsan sed "
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74 + "suscipit felis pulvinar. Nullam faucibus suscipit gravida. "
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75 + "Pellentesque habitant morbi tristique senectus et netus et "
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76 + "malesuada fames ac turpis egestas. Nullam ut massa augue, "
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77 + "nec viverra mauris.";
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78
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79 private static int getNextCount() {
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80 return count++;
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81 }
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82
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83 ////// end statics
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84
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85 private JavaCompiler javac;
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86 private String nameBase;
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87
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88 public GeneratedClassLoader() {
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89 javac = ToolProvider.getSystemJavaCompiler();
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90 nameBase = "TestSimpleClass";
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91 }
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92
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93 private long getBigValue(int which) {
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94 // > 65536 is too large to encode in the bytecode
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95 // so this will force us to emit a constant pool entry for this int
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96 return (long)which + 65537;
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97 }
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98
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99 private String getBigString(int which) {
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100 return bigstr + which;
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101 }
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102
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103 private String getClassName(int count) {
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104 return nameBase + count;
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105 }
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106
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107 private String generateSource(int count, int sizeFactor, int numClasses) {
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108 StringBuilder sb = new StringBuilder();
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109 sb.append("public class ").append(getClassName(count)).append("{\n");
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110 for (int j = 0; j < numClasses; ++j) {
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111 sb.append("public static class ")
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112 .append("Class")
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113 .append(j)
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114 .append("{\n");
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115 for (int i = 0; i < sizeFactor; ++i) {
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116 int value = i;
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117 sb.append("private long field")
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118 .append(i).append(" = ")
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119 .append(getBigValue(value++))
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120 .append(";\n");
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121 sb.append("public long method")
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122 .append(i)
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123 .append("() {\n");
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124 sb.append("return ")
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125 .append(getBigValue(value++))
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126 .append(";");
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127 sb.append("}\n");
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128 sb.append("private String str").append(i)
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129 .append(" = \"")
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130 .append(getBigString(i))
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131 .append("\";");
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132 }
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133 sb.append("\n}");
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134 }
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135 sb.append("\n}");
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136 return sb.toString();
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137 }
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138
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139 private GeneratedClass[] getGeneratedClass(int sizeFactor, int numClasses) throws IOException {
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140 int uniqueCount = getNextCount();
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141 String src = generateSource(uniqueCount, sizeFactor, numClasses);
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142 String className = getClassName(uniqueCount);
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143 File file = new File(className + ".java");
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144 try (PrintWriter pw = new PrintWriter(new FileWriter(file))) {
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145 pw.append(src);
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146 pw.flush();
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147 }
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148 int exitcode = javac.run(null, null, null, file.getCanonicalPath());
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149 if (exitcode != 0) {
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150 throw new RuntimeException("javac failure when compiling: " +
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151 file.getCanonicalPath());
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152 } else {
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153 if (deleteFiles) {
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154 file.delete();
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155 }
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156 }
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157 GeneratedClass[] gc = new GeneratedClass[numClasses];
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158 for (int i = 0; i < numClasses; ++i) {
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159 String name = className + "$" + "Class" + i;
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160 File classFile = new File(name + ".class");
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161 byte[] bytes;
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162 try (DataInputStream dis = new DataInputStream(new FileInputStream(classFile))) {
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163 bytes = new byte[dis.available()];
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164 dis.readFully(bytes);
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165 }
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166 if (deleteFiles) {
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167 classFile.delete();
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168 }
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169 gc[i] = new GeneratedClass(bytes, name);
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170 }
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171 if (deleteFiles) {
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172 new File(className + ".class").delete();
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173 }
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174 return gc;
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175 }
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176
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177 /**
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178 * Generate a single class, compile it and load it.
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179 * @param sizeFactor Fuzzy measure of how large the class should be.
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180 * @return the Class instance.
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181 * @throws IOException
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182 */
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183 public Class<?> generateClass(int sizeFactor) throws IOException {
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184 return getGeneratedClasses(sizeFactor, 1)[0];
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185 }
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186
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187 /**
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188 * Generate several classes, compile and load them.
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189 * @param sizeFactor Fuzzy measure of how large each class should be.
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190 * @param numClasses The number of classes to create
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191 * @return an array of the Class instances.
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192 * @throws IOException
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193 */
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194 public Class<?>[] getGeneratedClasses(int sizeFactor, int numClasses) throws IOException {
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195 GeneratedClass[] gc = getGeneratedClass(sizeFactor, numClasses);
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196 Class<?>[] classes = new Class[numClasses];
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197 for (int i = 0; i < numClasses; ++i) {
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198 classes[i] = defineClass(gc[i].name, gc[i].bytes, 0 , gc[i].bytes.length);
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199 }
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200 return classes;
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201 }
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202 }
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