| 1 | /* This file is part of the project "Hilbert II" - http://www.qedeq.org |
| 2 | * |
| 3 | * Copyright 2000-2014, Michael Meyling <mime@qedeq.org>. |
| 4 | * |
| 5 | * "Hilbert II" is free software; you can redistribute |
| 6 | * it and/or modify it under the terms of the GNU General Public |
| 7 | * License as published by the Free Software Foundation; either |
| 8 | * version 2 of the License, or (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | */ |
| 15 | |
| 16 | package org.qedeq.base.utility; |
| 17 | |
| 18 | import java.lang.reflect.Field; |
| 19 | import java.lang.reflect.InvocationTargetException; |
| 20 | import java.lang.reflect.Method; |
| 21 | |
| 22 | |
| 23 | /** |
| 24 | * We learned so much from the great Jedi master. Using the force we can get and set private |
| 25 | * fields of arbitrary objects. We can even execute private methods... |
| 26 | * |
| 27 | * @author Michael Meyling |
| 28 | */ |
| 29 | public abstract class YodaUtility { |
| 30 | |
| 31 | /** |
| 32 | * Constructor, should never be called. |
| 33 | */ |
| 34 | private YodaUtility() { |
| 35 | // don't call me |
| 36 | } |
| 37 | |
| 38 | /** |
| 39 | * Analyze if a class or one of its super classes contains a given method. |
| 40 | * <p> |
| 41 | * Example: you can test with <code>YodaUtility.existsMethod("java.net.URLConnection", |
| 42 | * "setConnectTimeout", new Class[] {Integer.TYPE}</code> with JDK 1.4.2 and if you run it |
| 43 | * with a 1.5 JRE or higher then it will be successfully executed. |
| 44 | * |
| 45 | * @param clazz Class to analyze. |
| 46 | * @param name Method name. |
| 47 | * @param parameterTypes Parameter types. |
| 48 | * @return Does the class (or one of its super classes) have such a method? |
| 49 | */ |
| 50 | public static boolean existsMethod(final String clazz, final String name, |
| 51 | final Class[] parameterTypes) { |
| 52 | Class c; |
| 53 | try { |
| 54 | c = Class.forName(clazz); |
| 55 | } catch (ClassNotFoundException e) { |
| 56 | return false; |
| 57 | } |
| 58 | return existsMethod(c, name, parameterTypes); |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | * Analyze if a class or one of its super classes contains a given method. |
| 63 | * <p> |
| 64 | * Example: you can test with <code>YodaUtility.existsMethod(URLConnection.class, |
| 65 | * "setConnectTimeout", new Class[] {Integer.TYPE}</code> with JDK 1.4.2 and if you run it |
| 66 | * with a 1.5 JRE or higher then it will be successfully executed. |
| 67 | * |
| 68 | * @param clazz Class to analyze. |
| 69 | * @param name Method name. |
| 70 | * @param parameterTypes Parameter types. |
| 71 | * @return Does the class (or one of its super classes) have such a method? |
| 72 | */ |
| 73 | public static boolean existsMethod(final Class clazz, final String name, |
| 74 | final Class[] parameterTypes) { |
| 75 | Method method = null; |
| 76 | Class cl = clazz; |
| 77 | try { |
| 78 | while (!Object.class.equals(cl)) { |
| 79 | try { |
| 80 | method = cl.getDeclaredMethod(name, parameterTypes); |
| 81 | break; |
| 82 | } catch (NoSuchMethodException ex) { |
| 83 | cl = cl.getSuperclass(); |
| 84 | } |
| 85 | } |
| 86 | if (method == null) { |
| 87 | return false; |
| 88 | } |
| 89 | return true; |
| 90 | } catch (SecurityException e) { |
| 91 | throw new RuntimeException(e); |
| 92 | } |
| 93 | } |
| 94 | |
| 95 | /** |
| 96 | * This method executes a method on an object or one of its super instances (even if it is |
| 97 | * private). |
| 98 | * <p> |
| 99 | * Example: you can compile <code>YodaUtility.executeMethod((URLConnection) httpConnection, |
| 100 | * "setConnectTimeout", new Class[] {Integer.TYPE}, new Object[] { new Integer(100)});</code> |
| 101 | * with JDK 1.4.2 and if you run it with a 1.5 JRE or higher then it will be successfully |
| 102 | * executed. |
| 103 | * |
| 104 | * @param obj Object. |
| 105 | * @param name Method name. |
| 106 | * @param parameterTypes Parameter types. |
| 107 | * @param parameter Parameter values. |
| 108 | * @return Execution result. |
| 109 | * @throws NoSuchMethodException Method not found. |
| 110 | * @throws InvocationTargetException Wrapped exception. |
| 111 | */ |
| 112 | public static Object executeMethod(final Object obj, final String name, |
| 113 | final Class[] parameterTypes, final Object[] parameter) throws NoSuchMethodException, |
| 114 | InvocationTargetException { |
| 115 | Method method = null; |
| 116 | try { |
| 117 | Class cl = obj.getClass(); |
| 118 | while (!Object.class.equals(cl)) { |
| 119 | try { |
| 120 | method = cl.getDeclaredMethod(name, parameterTypes); |
| 121 | break; |
| 122 | } catch (NoSuchMethodException ex) { |
| 123 | cl = cl.getSuperclass(); |
| 124 | } |
| 125 | } |
| 126 | if (method == null) { |
| 127 | throw new NoSuchMethodException(name); |
| 128 | } |
| 129 | method.setAccessible(true); |
| 130 | } catch (SecurityException e) { |
| 131 | throw new RuntimeException(e); |
| 132 | } |
| 133 | try { |
| 134 | return method.invoke(obj, parameter); |
| 135 | } catch (IllegalArgumentException e) { |
| 136 | throw new RuntimeException(e); |
| 137 | } catch (IllegalAccessException e) { |
| 138 | throw new RuntimeException(e); |
| 139 | } |
| 140 | } |
| 141 | |
| 142 | /** |
| 143 | * This method executes a static class method (even if it is private). |
| 144 | * <p> |
| 145 | * Example: you can compile <code>YodaUtility.executeMethod( |
| 146 | * "java.util.concurrent.locks.LockSupport", |
| 147 | * "park", new Class[0], new Object[0]);</code> |
| 148 | * with JDK 1.4.2 and if you run it with a 1.5 JRE or higher then it will be successfully |
| 149 | * executed. |
| 150 | * |
| 151 | * @param clazzName Name of class. |
| 152 | * @param name Name of static method to execute. |
| 153 | * @param parameterTypes Parameter types. |
| 154 | * @param parameter Parameter values. |
| 155 | * @return Execution result. |
| 156 | * @throws NoSuchMethodException Method not found. |
| 157 | * @throws InvocationTargetException Wrapped exception. |
| 158 | */ |
| 159 | public static Object executeMethod(final String clazzName, final String name, |
| 160 | final Class[] parameterTypes, final Object[] parameter) throws NoSuchMethodException, |
| 161 | InvocationTargetException { |
| 162 | Method method = null; |
| 163 | try { |
| 164 | Class cl = Class.forName(clazzName); |
| 165 | method = cl.getDeclaredMethod(name, parameterTypes); |
| 166 | if (method == null) { |
| 167 | throw new NoSuchMethodException(name); |
| 168 | } |
| 169 | method.setAccessible(true); |
| 170 | return method.invoke(cl, parameter); |
| 171 | } catch (SecurityException e) { |
| 172 | throw new RuntimeException(e); |
| 173 | } catch (ClassNotFoundException e) { |
| 174 | throw new RuntimeException(e); |
| 175 | } catch (IllegalAccessException e) { |
| 176 | throw new RuntimeException(e); |
| 177 | } |
| 178 | } |
| 179 | |
| 180 | /** |
| 181 | * This method returns the contents of an object variable .The class hierarchy is recursively |
| 182 | * searched to find such a field (even if it is private). |
| 183 | * |
| 184 | * @param obj Object. |
| 185 | * @param name Variable name. |
| 186 | * @return Contents of variable. |
| 187 | * @throws NoSuchFieldException Variable of given name was not found. |
| 188 | */ |
| 189 | public static Object getFieldValue(final Object obj, final String name) throws NoSuchFieldException { |
| 190 | final Field field = getField(obj, name); |
| 191 | try { |
| 192 | return field.get(obj); |
| 193 | } catch (IllegalArgumentException e) { |
| 194 | throw new RuntimeException(e); |
| 195 | } catch (IllegalAccessException e) { |
| 196 | throw new RuntimeException(e); |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | /** |
| 201 | * This method sets the contents of an object variable. The class hierarchy is recursively |
| 202 | * searched to find such a field (even if it is private). |
| 203 | * |
| 204 | * @param obj Object. |
| 205 | * @param name Variable name. |
| 206 | * @param value Value to set. |
| 207 | * @throws NoSuchFieldException Variable of given name was not found. |
| 208 | */ |
| 209 | public static void setFieldContent(final Object obj, final String name, final Object value) |
| 210 | throws NoSuchFieldException { |
| 211 | final Field field = getField(obj, name); |
| 212 | try { |
| 213 | field.set(obj, value); |
| 214 | } catch (IllegalArgumentException e) { |
| 215 | throw new RuntimeException(e); |
| 216 | } catch (IllegalAccessException e) { |
| 217 | throw new RuntimeException(e); |
| 218 | } |
| 219 | } |
| 220 | |
| 221 | /** |
| 222 | * Get field of given name in given object. The class hierarchy is recursively searched |
| 223 | * to find such a field (even if it is private). |
| 224 | * |
| 225 | * @param obj Object to work on. |
| 226 | * @param name Search this field. |
| 227 | * @return Found field. |
| 228 | * @throws NoSuchFieldException Field with name <code>name</code> was not found. |
| 229 | */ |
| 230 | public static Field getField(final Object obj, final String name) throws NoSuchFieldException { |
| 231 | Field field = null; |
| 232 | try { |
| 233 | Class cl = obj.getClass(); |
| 234 | while (!Object.class.equals(cl)) { |
| 235 | try { |
| 236 | field = cl.getDeclaredField(name); |
| 237 | break; |
| 238 | } catch (NoSuchFieldException ex) { |
| 239 | cl = cl.getSuperclass(); |
| 240 | } |
| 241 | } |
| 242 | if (field == null) { |
| 243 | throw (new NoSuchFieldException(name + " within " + obj.getClass())); |
| 244 | } |
| 245 | field.setAccessible(true); |
| 246 | } catch (SecurityException e) { |
| 247 | throw new RuntimeException(e); |
| 248 | } |
| 249 | return field; |
| 250 | } |
| 251 | |
| 252 | } |
| 253 | |