| 1 | /* |
| 2 | * Copyright 2006-2007 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.springframework.batch.item; |
| 18 | |
| 19 | import java.io.Serializable; |
| 20 | import java.util.Map; |
| 21 | import java.util.Set; |
| 22 | import java.util.Map.Entry; |
| 23 | import java.util.concurrent.ConcurrentHashMap; |
| 24 | |
| 25 | import org.springframework.util.Assert; |
| 26 | |
| 27 | /** |
| 28 | * Object representing a context for an {@link ItemStream}. It is a thin wrapper |
| 29 | * for a map that allows optionally for type safety on reads. It also allows for |
| 30 | * dirty checking by setting a 'dirty' flag whenever any put is called. |
| 31 | * |
| 32 | * Note that putting <code>null</code> value is equivalent to removing the entry |
| 33 | * for the given key. |
| 34 | * |
| 35 | * @author Lucas Ward |
| 36 | * @author Douglas Kaminsky |
| 37 | */ |
| 38 | public class ExecutionContext implements Serializable { |
| 39 | |
| 40 | private volatile boolean dirty = false; |
| 41 | |
| 42 | private final Map<String, Object> map; |
| 43 | |
| 44 | /** |
| 45 | * Default constructor. Initializes a new execution context with an empty |
| 46 | * internal map. |
| 47 | */ |
| 48 | public ExecutionContext() { |
| 49 | map = new ConcurrentHashMap<String, Object>(); |
| 50 | } |
| 51 | |
| 52 | /** |
| 53 | * Initializes a new execution context with the contents of another map. |
| 54 | * |
| 55 | * @param map Initial contents of context. |
| 56 | */ |
| 57 | public ExecutionContext(Map<String, Object> map) { |
| 58 | this.map = new ConcurrentHashMap<String, Object>(map); |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | * @param executionContext |
| 63 | */ |
| 64 | public ExecutionContext(ExecutionContext executionContext) { |
| 65 | this(); |
| 66 | if (executionContext == null) { |
| 67 | return; |
| 68 | } |
| 69 | for (Entry<String, Object> entry : executionContext.entrySet()) { |
| 70 | this.map.put(entry.getKey(), entry.getValue()); |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | /** |
| 75 | * Adds a String value to the context. |
| 76 | * |
| 77 | * @param key Key to add to context |
| 78 | * @param value Value to associate with key |
| 79 | */ |
| 80 | |
| 81 | public void putString(String key, String value) { |
| 82 | |
| 83 | put(key, value); |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Adds a Long value to the context. |
| 88 | * |
| 89 | * @param key Key to add to context |
| 90 | * @param value Value to associate with key |
| 91 | */ |
| 92 | public void putLong(String key, long value) { |
| 93 | |
| 94 | put(key, Long.valueOf(value)); |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * Adds an Integer value to the context. |
| 99 | * |
| 100 | * @param key Key to add to context |
| 101 | * @param value Value to associate with key |
| 102 | */ |
| 103 | public void putInt(String key, int value) { |
| 104 | put(key, Integer.valueOf(value)); |
| 105 | } |
| 106 | |
| 107 | /** |
| 108 | * Add a Double value to the context. |
| 109 | * |
| 110 | * @param key Key to add to context |
| 111 | * @param value Value to associate with key |
| 112 | */ |
| 113 | public void putDouble(String key, double value) { |
| 114 | |
| 115 | put(key, Double.valueOf(value)); |
| 116 | } |
| 117 | |
| 118 | /** |
| 119 | * Add an Object value to the context (must be Serializable). Putting |
| 120 | * <code>null</code> value for a given key removes the key. |
| 121 | * |
| 122 | * @param key Key to add to context |
| 123 | * @param value Value to associate with key |
| 124 | */ |
| 125 | public void put(String key, Object value) { |
| 126 | if (value != null) { |
| 127 | Assert.isInstanceOf(Serializable.class, value, "Value: [ " + value + "must be serializable."); |
| 128 | Object result = map.put(key, value); |
| 129 | dirty = result==null || result!=null && !result.equals(value); |
| 130 | } |
| 131 | else { |
| 132 | Object result = map.remove(key); |
| 133 | dirty = result!=null; |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | /** |
| 138 | * Indicates if context has been changed with a "put" operation since the |
| 139 | * dirty flag was last cleared. Note that the last time the flag was cleared |
| 140 | * might correspond to creation of the context. |
| 141 | * |
| 142 | * @return True if "put" operation has occurred since flag was last cleared |
| 143 | */ |
| 144 | public boolean isDirty() { |
| 145 | return dirty; |
| 146 | } |
| 147 | |
| 148 | /** |
| 149 | * Typesafe Getter for the String represented by the provided key. |
| 150 | * |
| 151 | * @param key The key to get a value for |
| 152 | * @return The <code>String</code> value |
| 153 | */ |
| 154 | public String getString(String key) { |
| 155 | |
| 156 | return (String) readAndValidate(key, String.class); |
| 157 | } |
| 158 | |
| 159 | /** |
| 160 | * Typesafe Getter for the String represented by the provided key with |
| 161 | * default value to return if key is not represented. |
| 162 | * |
| 163 | * @param key The key to get a value for |
| 164 | * @param defaultString Default to return if key is not represented |
| 165 | * @return The <code>String</code> value if key is repreesnted, specified |
| 166 | * default otherwise |
| 167 | */ |
| 168 | public String getString(String key, String defaultString) { |
| 169 | if (!map.containsKey(key)) { |
| 170 | return defaultString; |
| 171 | } |
| 172 | |
| 173 | return (String) readAndValidate(key, String.class); |
| 174 | } |
| 175 | |
| 176 | /** |
| 177 | * Typesafe Getter for the Long represented by the provided key. |
| 178 | * |
| 179 | * @param key The key to get a value for |
| 180 | * @return The <code>Long</code> value |
| 181 | */ |
| 182 | public long getLong(String key) { |
| 183 | |
| 184 | return ((Long) readAndValidate(key, Long.class)).longValue(); |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * Typesafe Getter for the Long represented by the provided key with default |
| 189 | * value to return if key is not represented. |
| 190 | * |
| 191 | * @param key The key to get a value for |
| 192 | * @param defaultLong Default to return if key is not represented |
| 193 | * @return The <code>long</code> value if key is represented, specified |
| 194 | * default otherwise |
| 195 | */ |
| 196 | public long getLong(String key, long defaultLong) { |
| 197 | if (!map.containsKey(key)) { |
| 198 | return defaultLong; |
| 199 | } |
| 200 | |
| 201 | return ((Long) readAndValidate(key, Long.class)).longValue(); |
| 202 | } |
| 203 | |
| 204 | /** |
| 205 | * Typesafe Getter for the Integer represented by the provided key. |
| 206 | * |
| 207 | * @param key The key to get a value for |
| 208 | * @return The <code>Integer</code> value |
| 209 | */ |
| 210 | public int getInt(String key) { |
| 211 | |
| 212 | return ((Integer) readAndValidate(key, Integer.class)).intValue(); |
| 213 | } |
| 214 | |
| 215 | /** |
| 216 | * Typesafe Getter for the Integer represented by the provided key with |
| 217 | * default value to return if key is not represented. |
| 218 | * |
| 219 | * @param key The key to get a value for |
| 220 | * @param defaultInt Default to return if key is not represented |
| 221 | * @return The <code>int</code> value if key is represented, specified |
| 222 | * default otherwise |
| 223 | */ |
| 224 | public int getInt(String key, int defaultInt) { |
| 225 | if (!map.containsKey(key)) { |
| 226 | return defaultInt; |
| 227 | } |
| 228 | |
| 229 | return ((Integer) readAndValidate(key, Integer.class)).intValue(); |
| 230 | } |
| 231 | |
| 232 | /** |
| 233 | * Typesafe Getter for the Double represented by the provided key. |
| 234 | * |
| 235 | * @param key The key to get a value for |
| 236 | * @return The <code>Double</code> value |
| 237 | */ |
| 238 | public double getDouble(String key) { |
| 239 | return ((Double) readAndValidate(key, Double.class)).doubleValue(); |
| 240 | } |
| 241 | |
| 242 | /** |
| 243 | * Typesafe Getter for the Double represented by the provided key with |
| 244 | * default value to return if key is not represented. |
| 245 | * |
| 246 | * @param key The key to get a value for |
| 247 | * @param defaultDouble Default to return if key is not represented |
| 248 | * @return The <code>double</code> value if key is represented, specified |
| 249 | * default otherwise |
| 250 | */ |
| 251 | public double getDouble(String key, double defaultDouble) { |
| 252 | if (!map.containsKey(key)) { |
| 253 | return defaultDouble; |
| 254 | } |
| 255 | |
| 256 | return ((Double) readAndValidate(key, Double.class)).doubleValue(); |
| 257 | } |
| 258 | |
| 259 | /** |
| 260 | * Getter for the value represented by the provided key. |
| 261 | * |
| 262 | * @param key The key to get a value for |
| 263 | * @return The value represented by the given key |
| 264 | */ |
| 265 | public Object get(String key) { |
| 266 | return map.get(key); |
| 267 | } |
| 268 | |
| 269 | /** |
| 270 | * Utility method that attempts to take a value represented by a given key |
| 271 | * and validate it as a member of the specified type. |
| 272 | * |
| 273 | * @param key The key to validate a value for |
| 274 | * @param type Class against which value should be validated |
| 275 | * @return Value typed to the specified <code>Class</code> |
| 276 | */ |
| 277 | private Object readAndValidate(String key, Class<?> type) { |
| 278 | |
| 279 | Object value = map.get(key); |
| 280 | |
| 281 | if (!type.isInstance(value)) { |
| 282 | throw new ClassCastException("Value for key=[" + key + "] is not of type: [" + type + "], it is [" |
| 283 | + (value == null ? null : "(" + value.getClass() + ")" + value) + "]"); |
| 284 | } |
| 285 | |
| 286 | return value; |
| 287 | } |
| 288 | |
| 289 | /** |
| 290 | * Indicates whether or not the context is empty. |
| 291 | * |
| 292 | * @return True if the context has no entries, false otherwise. |
| 293 | * @see java.util.Map#isEmpty() |
| 294 | */ |
| 295 | public boolean isEmpty() { |
| 296 | return map.isEmpty(); |
| 297 | } |
| 298 | |
| 299 | /** |
| 300 | * Clears the dirty flag. |
| 301 | */ |
| 302 | public void clearDirtyFlag() { |
| 303 | dirty = false; |
| 304 | } |
| 305 | |
| 306 | /** |
| 307 | * Returns the entry set containing the contents of this context. |
| 308 | * |
| 309 | * @return A set representing the contents of the context |
| 310 | * @see java.util.Map#entrySet() |
| 311 | */ |
| 312 | public Set<Entry<String, Object>> entrySet() { |
| 313 | return map.entrySet(); |
| 314 | } |
| 315 | |
| 316 | /** |
| 317 | * Indicates whether or not a key is represented in this context. |
| 318 | * |
| 319 | * @param key Key to check existence for |
| 320 | * @return True if key is represented in context, false otherwise |
| 321 | * @see java.util.Map#containsKey(Object) |
| 322 | */ |
| 323 | public boolean containsKey(String key) { |
| 324 | return map.containsKey(key); |
| 325 | } |
| 326 | |
| 327 | /** |
| 328 | * Removes the mapping for a key from this context if it is present. |
| 329 | * |
| 330 | * @see java.util.Map#remove(Object) |
| 331 | */ |
| 332 | public Object remove(String key) { |
| 333 | return map.remove(key); |
| 334 | } |
| 335 | |
| 336 | /** |
| 337 | * Indicates whether or not a value is represented in this context. |
| 338 | * |
| 339 | * @param value Value to check existence for |
| 340 | * @return True if value is represented in context, false otherwise |
| 341 | * @see java.util.Map#containsValue(Object) |
| 342 | */ |
| 343 | public boolean containsValue(Object value) { |
| 344 | return map.containsValue(value); |
| 345 | } |
| 346 | |
| 347 | /* |
| 348 | * (non-Javadoc) |
| 349 | * |
| 350 | * @see java.lang.Object#equals(java.lang.Object) |
| 351 | */ |
| 352 | public boolean equals(Object obj) { |
| 353 | if (obj instanceof ExecutionContext == false) { |
| 354 | return false; |
| 355 | } |
| 356 | if (this == obj) { |
| 357 | return true; |
| 358 | } |
| 359 | ExecutionContext rhs = (ExecutionContext) obj; |
| 360 | return this.entrySet().equals(rhs.entrySet()); |
| 361 | } |
| 362 | |
| 363 | /* |
| 364 | * (non-Javadoc) |
| 365 | * |
| 366 | * @see java.lang.Object#hashCode() |
| 367 | */ |
| 368 | public int hashCode() { |
| 369 | return map.hashCode(); |
| 370 | } |
| 371 | |
| 372 | /* |
| 373 | * (non-Javadoc) |
| 374 | * |
| 375 | * @see java.lang.Object#toString() |
| 376 | */ |
| 377 | public String toString() { |
| 378 | return map.toString(); |
| 379 | } |
| 380 | |
| 381 | /** |
| 382 | * Returns number of entries in the context |
| 383 | * |
| 384 | * @return Number of entries in the context |
| 385 | * @see java.util.Map#size() |
| 386 | */ |
| 387 | public int size() { |
| 388 | return map.size(); |
| 389 | } |
| 390 | |
| 391 | } |