Stuart McCulloch | bb01437 | 2012-06-07 21:57:32 +0000 | [diff] [blame^] | 1 | package aQute.lib.json; |
| 2 | |
| 3 | import java.io.*; |
| 4 | import java.lang.reflect.*; |
| 5 | import java.util.*; |
| 6 | import java.util.regex.*; |
| 7 | |
| 8 | /** |
| 9 | * This is a simple JSON Coder and Encoder that uses the Java type system to |
| 10 | * convert data objects to JSON and JSON to (type safe) Java objects. The |
| 11 | * conversion is very much driven by classes and their public fields. Generic |
| 12 | * information, when present is taken into account. </p> Usage patterns to |
| 13 | * encode: |
| 14 | * |
| 15 | * <pre> |
| 16 | * JSONCoder codec = new JSONCodec(); // |
| 17 | * assert "1".equals( codec.enc().to().put(1).toString()); |
| 18 | * assert "[1,2,3]".equals( codec.enc().to().put(Arrays.asList(1,2,3).toString()); |
| 19 | * |
| 20 | * Map m = new HashMap(); |
| 21 | * m.put("a", "A"); |
| 22 | * assert "{\"a\":\"A\"}".equals( codec.enc().to().put(m).toString()); |
| 23 | * |
| 24 | * static class D { public int a; } |
| 25 | * D d = new D(); |
| 26 | * d.a = 41; |
| 27 | * assert "{\"a\":41}".equals( codec.enc().to().put(d).toString()); |
| 28 | * </pre> |
| 29 | * |
| 30 | * It is possible to redirect the encoder to another output (default is a |
| 31 | * string). See {@link Encoder#to()},{@link Encoder#to(File))}, |
| 32 | * {@link Encoder#to(OutputStream)}, {@link Encoder#to(Appendable))}. To reset |
| 33 | * the string output call {@link Encoder#to()}. |
| 34 | * <p/> |
| 35 | * This Codec class can be used in a concurrent environment. The Decoders and |
| 36 | * Encoders, however, must only be used in a single thread. |
| 37 | */ |
| 38 | public class JSONCodec { |
| 39 | final static String START_CHARACTERS = "[{\"-0123456789tfn"; |
| 40 | |
| 41 | // Handlers |
| 42 | private final static WeakHashMap<Type, Handler> handlers = new WeakHashMap<Type, Handler>(); |
| 43 | private static StringHandler sh = new StringHandler(); |
| 44 | private static BooleanHandler bh = new BooleanHandler(); |
| 45 | private static CharacterHandler ch = new CharacterHandler(); |
| 46 | private static CollectionHandler dch = new CollectionHandler( |
| 47 | ArrayList.class, |
| 48 | Object.class); |
| 49 | private static SpecialHandler sph = new SpecialHandler( |
| 50 | Pattern.class, |
| 51 | null, null); |
| 52 | private static DateHandler sdh = new DateHandler(); |
| 53 | private static FileHandler fh = new FileHandler(); |
| 54 | private static ByteArrayHandler byteh = new ByteArrayHandler(); |
| 55 | |
| 56 | /** |
| 57 | * Create a new Encoder with the state and appropriate API. |
| 58 | * |
| 59 | * @return an Encoder |
| 60 | */ |
| 61 | public Encoder enc() { |
| 62 | return new Encoder(this); |
| 63 | } |
| 64 | |
| 65 | /** |
| 66 | * Create a new Decoder with the state and appropriate API. |
| 67 | * |
| 68 | * @return a Decoder |
| 69 | */ |
| 70 | public Decoder dec() { |
| 71 | return new Decoder(this); |
| 72 | } |
| 73 | |
| 74 | /* |
| 75 | * Work horse encode methods, all encoding ends up here. |
| 76 | */ |
| 77 | void encode(Encoder app, Object object, Type type, Map<Object, Type> visited) throws Exception { |
| 78 | |
| 79 | // Get the null out of the way |
| 80 | |
| 81 | if (object == null) { |
| 82 | app.append("null"); |
| 83 | return; |
| 84 | } |
| 85 | |
| 86 | // If we have no type or the type is Object.class |
| 87 | // we take the type of the object itself. Normally types |
| 88 | // come from declaration sites (returns, fields, methods, etc) |
| 89 | // and contain generic info. |
| 90 | |
| 91 | if (type == null || type == Object.class) |
| 92 | type = object.getClass(); |
| 93 | |
| 94 | // Dispatch to the handler who knows how to handle the given type. |
| 95 | Handler h = getHandler(type); |
| 96 | h.encode(app, object, visited); |
| 97 | } |
| 98 | |
| 99 | /* |
| 100 | * This method figures out which handler should handle the type specific |
| 101 | * stuff. It returns a handler for each type. If no appropriate handler |
| 102 | * exists, it will create one for the given type. There are actually quite a |
| 103 | * lot of handlers since Java is not very object oriented. |
| 104 | * |
| 105 | * @param type |
| 106 | * |
| 107 | * @return |
| 108 | * |
| 109 | * @throws Exception |
| 110 | */ |
| 111 | Handler getHandler(Type type) throws Exception { |
| 112 | |
| 113 | // First the static hard coded handlers for the common types. |
| 114 | |
| 115 | if (type == String.class) |
| 116 | return sh; |
| 117 | |
| 118 | if (type == Boolean.class || type == boolean.class) |
| 119 | return bh; |
| 120 | |
| 121 | if (type == byte[].class) |
| 122 | return byteh; |
| 123 | |
| 124 | if (Character.class == type || char.class == type) |
| 125 | return ch; |
| 126 | |
| 127 | if (Pattern.class == type) |
| 128 | return sph; |
| 129 | |
| 130 | if (Date.class == type) |
| 131 | return sdh; |
| 132 | |
| 133 | if (File.class == type) |
| 134 | return fh; |
| 135 | |
| 136 | Handler h; |
| 137 | synchronized (handlers) { |
| 138 | h = handlers.get(type); |
| 139 | } |
| 140 | |
| 141 | if (h != null) |
| 142 | return h; |
| 143 | |
| 144 | if (type instanceof Class) { |
| 145 | |
| 146 | Class<?> clazz = (Class<?>) type; |
| 147 | |
| 148 | if (Enum.class.isAssignableFrom(clazz)) |
| 149 | h = new EnumHandler(clazz); |
| 150 | else if (Collection.class.isAssignableFrom(clazz)) // A Non Generic |
| 151 | // collection |
| 152 | |
| 153 | h = dch; |
| 154 | else if (clazz.isArray()) // Non generic array |
| 155 | h = new ArrayHandler(clazz, clazz.getComponentType()); |
| 156 | else if (Map.class.isAssignableFrom(clazz)) // A Non Generic map |
| 157 | h = new MapHandler(clazz, Object.class, Object.class); |
| 158 | else if (Number.class.isAssignableFrom(clazz) || clazz.isPrimitive()) |
| 159 | h = new NumberHandler(clazz); |
| 160 | else { |
| 161 | Method valueOf = null; |
| 162 | Constructor<?> constructor = null; |
| 163 | |
| 164 | try { |
| 165 | constructor = clazz.getConstructor(String.class); |
| 166 | } catch (Exception e) { |
| 167 | // Ignore |
| 168 | } |
| 169 | try { |
| 170 | valueOf = clazz.getMethod("valueOf", String.class); |
| 171 | } catch (Exception e) { |
| 172 | // Ignore |
| 173 | } |
| 174 | if (constructor != null || valueOf != null) |
| 175 | h = new SpecialHandler(clazz, constructor, valueOf); |
| 176 | else |
| 177 | h = new ObjectHandler(this, clazz); // Hmm, might not be a |
| 178 | // data class ... |
| 179 | } |
| 180 | |
| 181 | } else { |
| 182 | |
| 183 | // We have generic information available |
| 184 | // We only support generics on Collection, Map, and arrays |
| 185 | |
| 186 | if (type instanceof ParameterizedType) { |
| 187 | ParameterizedType pt = (ParameterizedType) type; |
| 188 | Type rawType = pt.getRawType(); |
| 189 | if (rawType instanceof Class) { |
| 190 | Class<?> rawClass = (Class<?>) rawType; |
| 191 | if (Collection.class.isAssignableFrom(rawClass)) |
| 192 | h = new CollectionHandler(rawClass, pt.getActualTypeArguments()[0]); |
| 193 | else if (Map.class.isAssignableFrom(rawClass)) |
| 194 | h = new MapHandler(rawClass, pt.getActualTypeArguments()[0], |
| 195 | pt.getActualTypeArguments()[1]); |
| 196 | else |
| 197 | throw new IllegalArgumentException( |
| 198 | "Found a parameterized type that is not a map or collection"); |
| 199 | } |
| 200 | } else if (type instanceof GenericArrayType) { |
| 201 | GenericArrayType gat = (GenericArrayType) type; |
| 202 | h = new ArrayHandler(getRawClass(type), gat.getGenericComponentType()); |
| 203 | } else |
| 204 | throw new IllegalArgumentException( |
| 205 | "Found a parameterized type that is not a map or collection"); |
| 206 | } |
| 207 | synchronized (handlers) { |
| 208 | // We might actually have duplicates |
| 209 | // but who cares? They should be identical |
| 210 | handlers.put(type, h); |
| 211 | } |
| 212 | return h; |
| 213 | } |
| 214 | |
| 215 | Object decode(Type type, Decoder isr) throws Exception { |
| 216 | int c = isr.skipWs(); |
| 217 | Handler h; |
| 218 | |
| 219 | if (type == null || type == Object.class) { |
| 220 | |
| 221 | // Establish default behavior when we run without |
| 222 | // type information |
| 223 | |
| 224 | switch (c) { |
| 225 | case '{': |
| 226 | type = LinkedHashMap.class; |
| 227 | break; |
| 228 | |
| 229 | case '[': |
| 230 | type = ArrayList.class; |
| 231 | break; |
| 232 | |
| 233 | case '"': |
| 234 | return parseString(isr); |
| 235 | |
| 236 | case 'n': |
| 237 | isr.expect("ull"); |
| 238 | return null; |
| 239 | |
| 240 | case 't': |
| 241 | isr.expect("rue"); |
| 242 | return true; |
| 243 | |
| 244 | case 'f': |
| 245 | isr.expect("alse"); |
| 246 | return false; |
| 247 | |
| 248 | case '0': |
| 249 | case '1': |
| 250 | case '2': |
| 251 | case '3': |
| 252 | case '4': |
| 253 | case '5': |
| 254 | case '6': |
| 255 | case '7': |
| 256 | case '8': |
| 257 | case '9': |
| 258 | case '-': |
| 259 | return parseNumber(isr); |
| 260 | |
| 261 | default: |
| 262 | throw new IllegalArgumentException("Invalid character at begin of token: " |
| 263 | + (char) c); |
| 264 | } |
| 265 | } |
| 266 | |
| 267 | h = getHandler(type); |
| 268 | |
| 269 | switch (c) { |
| 270 | case '{': |
| 271 | return h.decodeObject(isr); |
| 272 | |
| 273 | case '[': |
| 274 | return h.decodeArray(isr); |
| 275 | |
| 276 | case '"': |
| 277 | return h.decode(parseString(isr)); |
| 278 | |
| 279 | case 'n': |
| 280 | isr.expect("ull"); |
| 281 | return h.decode(); |
| 282 | |
| 283 | case 't': |
| 284 | isr.expect("rue"); |
| 285 | return h.decode(Boolean.TRUE); |
| 286 | |
| 287 | case 'f': |
| 288 | isr.expect("alse"); |
| 289 | return h.decode(Boolean.FALSE); |
| 290 | |
| 291 | case '0': |
| 292 | case '1': |
| 293 | case '2': |
| 294 | case '3': |
| 295 | case '4': |
| 296 | case '5': |
| 297 | case '6': |
| 298 | case '7': |
| 299 | case '8': |
| 300 | case '9': |
| 301 | case '-': |
| 302 | return h.decode(parseNumber(isr)); |
| 303 | |
| 304 | default: |
| 305 | throw new IllegalArgumentException("Unexpected character in input stream: " + (char) c); |
| 306 | } |
| 307 | } |
| 308 | |
| 309 | String parseString(Decoder r) throws Exception { |
| 310 | assert r.current() == '"'; |
| 311 | |
| 312 | int c = r.next(); // skip first " |
| 313 | |
| 314 | StringBuilder sb = new StringBuilder(); |
| 315 | while (c != '"') { |
| 316 | if (c < 0 || Character.isISOControl(c)) |
| 317 | throw new IllegalArgumentException( |
| 318 | "JSON strings may not contain control characters: " + r.current()); |
| 319 | |
| 320 | if (c == '\\') { |
| 321 | c = r.read(); |
| 322 | switch (c) { |
| 323 | case '"': |
| 324 | case '\\': |
| 325 | case '/': |
| 326 | sb.append((char)c); |
| 327 | break; |
| 328 | |
| 329 | case 'b': |
| 330 | sb.append('\b'); |
| 331 | break; |
| 332 | |
| 333 | case 'f': |
| 334 | sb.append('\f'); |
| 335 | break; |
| 336 | case 'n': |
| 337 | sb.append('\n'); |
| 338 | break; |
| 339 | case 'r': |
| 340 | sb.append('\r'); |
| 341 | break; |
| 342 | case 't': |
| 343 | sb.append('\t'); |
| 344 | break; |
| 345 | case 'u': |
| 346 | int a3 = hexDigit(r.read()) << 12; |
| 347 | int a2 = hexDigit(r.read()) << 8; |
| 348 | int a1 = hexDigit(r.read()) << 4; |
| 349 | int a0 = hexDigit(r.read()) << 0; |
| 350 | c = a3 + a2 + a1 + a0; |
| 351 | sb.append((char) c); |
| 352 | break; |
| 353 | |
| 354 | default: |
| 355 | throw new IllegalArgumentException( |
| 356 | "The only characters after a backslash are \", \\, b, f, n, r, t, and u but got " |
| 357 | + c); |
| 358 | } |
| 359 | } else |
| 360 | sb.append((char) c); |
| 361 | |
| 362 | c = r.read(); |
| 363 | } |
| 364 | assert c == '"'; |
| 365 | r.read(); // skip quote |
| 366 | return sb.toString(); |
| 367 | } |
| 368 | |
| 369 | private int hexDigit(int c) throws EOFException { |
| 370 | if (c >= '0' && c <= '9') |
| 371 | return c - '0'; |
| 372 | |
| 373 | if (c >= 'A' && c <= 'F') |
| 374 | return c - 'A' + 10; |
| 375 | |
| 376 | if (c >= 'a' && c <= 'f') |
| 377 | return c - 'a' + 10; |
| 378 | |
| 379 | throw new IllegalArgumentException("Invalid hex character: " + c); |
| 380 | } |
| 381 | |
| 382 | private Number parseNumber(Decoder r) throws Exception { |
| 383 | StringBuilder sb = new StringBuilder(); |
| 384 | boolean d = false; |
| 385 | |
| 386 | if (r.current() == '-') { |
| 387 | sb.append('-'); |
| 388 | r.read(); |
| 389 | } |
| 390 | |
| 391 | int c = r.current(); |
| 392 | if (c == '0') { |
| 393 | sb.append('0'); |
| 394 | c = r.read(); |
| 395 | } else if (c >= '1' && c <= '9') { |
| 396 | sb.append((char) c); |
| 397 | c = r.read(); |
| 398 | |
| 399 | while (c >= '0' && c <= '9') { |
| 400 | sb.append((char) c); |
| 401 | c = r.read(); |
| 402 | } |
| 403 | } else |
| 404 | throw new IllegalArgumentException("Expected digit"); |
| 405 | |
| 406 | if (c == '.') { |
| 407 | d = true; |
| 408 | sb.append('.'); |
| 409 | c = r.read(); |
| 410 | while (c >= '0' && c <= '9') { |
| 411 | sb.append((char) c); |
| 412 | c = r.read(); |
| 413 | } |
| 414 | } |
| 415 | if (c == 'e' || c == 'E') { |
| 416 | d = true; |
| 417 | sb.append('e'); |
| 418 | c = r.read(); |
| 419 | if (c == '+') { |
| 420 | sb.append('+'); |
| 421 | c = r.read(); |
| 422 | } else if (c == '-') { |
| 423 | sb.append('-'); |
| 424 | c = r.read(); |
| 425 | } |
| 426 | while (c >= '0' && c <= '9') { |
| 427 | sb.append((char) c); |
| 428 | c = r.read(); |
| 429 | } |
| 430 | } |
| 431 | if (d) |
| 432 | return Double.parseDouble(sb.toString()); |
| 433 | long l = Long.parseLong(sb.toString()); |
| 434 | if (l > Integer.MAX_VALUE || l < Integer.MIN_VALUE) |
| 435 | return l; |
| 436 | return (int) l; |
| 437 | } |
| 438 | |
| 439 | void parseArray(Collection<Object> list, Type componentType, Decoder r) throws Exception { |
| 440 | assert r.current() == '['; |
| 441 | int c = r.next(); |
| 442 | while (START_CHARACTERS.indexOf(c) >= 0) { |
| 443 | Object o = decode(componentType, r); |
| 444 | list.add(o); |
| 445 | |
| 446 | c = r.skipWs(); |
| 447 | if (c == ']') |
| 448 | break; |
| 449 | |
| 450 | if (c == ',') { |
| 451 | c = r.next(); |
| 452 | continue; |
| 453 | } |
| 454 | |
| 455 | throw new IllegalArgumentException( |
| 456 | "Invalid character in parsing list, expected ] or , but found " + (char) c); |
| 457 | } |
| 458 | assert r.current() == ']'; |
| 459 | r.read(); // skip closing |
| 460 | } |
| 461 | |
| 462 | @SuppressWarnings("rawtypes") |
| 463 | Class<?> getRawClass(Type type) { |
| 464 | if (type instanceof Class) |
| 465 | return (Class) type; |
| 466 | |
| 467 | if (type instanceof ParameterizedType) |
| 468 | return getRawClass(((ParameterizedType) type).getRawType()); |
| 469 | |
| 470 | if (type instanceof GenericArrayType) { |
| 471 | Type subType = ((GenericArrayType) type).getGenericComponentType(); |
| 472 | Class c = getRawClass(subType); |
| 473 | return Array.newInstance(c, 0).getClass(); |
| 474 | } |
| 475 | |
| 476 | throw new IllegalArgumentException( |
| 477 | "Does not support generics beyond Parameterized Type and GenericArrayType, got " |
| 478 | + type); |
| 479 | } |
| 480 | |
| 481 | } |