001 /* $Id: CallMethodRule.java 499574 2007-01-24 21:25:51Z nuttycom $ 002 * 003 * Licensed to the Apache Software Foundation (ASF) under one or more 004 * contributor license agreements. See the NOTICE file distributed with 005 * this work for additional information regarding copyright ownership. 006 * The ASF licenses this file to You under the Apache License, Version 2.0 007 * (the "License"); you may not use this file except in compliance with 008 * the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019 020 package org.apache.commons.digester; 021 022 023 import org.apache.commons.beanutils.ConvertUtils; 024 import org.apache.commons.beanutils.MethodUtils; 025 import org.xml.sax.Attributes; 026 027 028 /** 029 * <p>Rule implementation that calls a method on an object on the stack 030 * (normally the top/parent object), passing arguments collected from 031 * subsequent <code>CallParamRule</code> rules or from the body of this 032 * element. </p> 033 * 034 * <p>By using {@link #CallMethodRule(String methodName)} 035 * a method call can be made to a method which accepts no 036 * arguments.</p> 037 * 038 * <p>Incompatible method parameter types are converted 039 * using <code>org.apache.commons.beanutils.ConvertUtils</code>. 040 * </p> 041 * 042 * <p>This rule now uses {@link MethodUtils#invokeMethod} by default. 043 * This increases the kinds of methods successfully and allows primitives 044 * to be matched by passing in wrapper classes. 045 * There are rare cases when {@link MethodUtils#invokeExactMethod} 046 * (the old default) is required. 047 * This method is much stricter in it's reflection. 048 * Setting the <code>UseExactMatch</code> to true reverts to the use of this 049 * method.</p> 050 * 051 * <p>Note that the target method is invoked when the <i>end</i> of 052 * the tag the CallMethodRule fired on is encountered, <i>not</i> when the 053 * last parameter becomes available. This implies that rules which fire on 054 * tags nested within the one associated with the CallMethodRule will 055 * fire before the CallMethodRule invokes the target method. This behaviour is 056 * not configurable. </p> 057 * 058 * <p>Note also that if a CallMethodRule is expecting exactly one parameter 059 * and that parameter is not available (eg CallParamRule is used with an 060 * attribute name but the attribute does not exist) then the method will 061 * not be invoked. If a CallMethodRule is expecting more than one parameter, 062 * then it is always invoked, regardless of whether the parameters were 063 * available or not; missing parameters are converted to the appropriate target 064 * type by calling ConvertUtils.convert. Note that the default ConvertUtils 065 * converters for the String type returns a null when passed a null, meaning 066 * that CallMethodRule will passed null for all String parameters for which 067 * there is no parameter info available from the XML. However parameters of 068 * type Float and Integer will be passed a real object containing a zero value 069 * as that is the output of the default ConvertUtils converters for those 070 * types when passed a null. You can register custom converters to change 071 * this behaviour; see the beautils library documentation for more info.</p> 072 * 073 * <p>Note that when a constructor is used with paramCount=0, indicating that 074 * the body of the element is to be passed to the target method, an empty 075 * element will cause an <i>empty string</i> to be passed to the target method, 076 * not null. And if automatic type conversion is being applied (ie if the 077 * target function takes something other than a string as a parameter) then 078 * the conversion will fail if the converter class does not accept an empty 079 * string as valid input.</p> 080 * 081 * <p>CallMethodRule has a design flaw which can cause it to fail under 082 * certain rule configurations. All CallMethodRule instances share a single 083 * parameter stack, and all CallParamRule instances simply store their data 084 * into the parameter-info structure that is on the top of the stack. This 085 * means that two CallMethodRule instances cannot be associated with the 086 * same pattern without getting scrambled parameter data. This same issue 087 * also applies when a CallMethodRule matches some element X, a different 088 * CallMethodRule matches a child element Y and some of the CallParamRules 089 * associated with the first CallMethodRule match element Y or one of its 090 * child elements. This issue has been present since the very first release 091 * of Digester. Note, however, that this configuration of CallMethodRule 092 * instances is not commonly required.</p> 093 */ 094 095 public class CallMethodRule extends Rule { 096 097 // ----------------------------------------------------------- Constructors 098 099 /** 100 * Construct a "call method" rule with the specified method name. The 101 * parameter types (if any) default to java.lang.String. 102 * 103 * @param digester The associated Digester 104 * @param methodName Method name of the parent method to call 105 * @param paramCount The number of parameters to collect, or 106 * zero for a single argument from the body of this element. 107 * 108 * 109 * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 110 * Use {@link #CallMethodRule(String methodName,int paramCount)} instead. 111 */ 112 public CallMethodRule(Digester digester, String methodName, 113 int paramCount) { 114 115 this(methodName, paramCount); 116 117 } 118 119 120 /** 121 * Construct a "call method" rule with the specified method name. 122 * 123 * @param digester The associated Digester 124 * @param methodName Method name of the parent method to call 125 * @param paramCount The number of parameters to collect, or 126 * zero for a single argument from the body of ths element 127 * @param paramTypes The Java class names of the arguments 128 * (if you wish to use a primitive type, specify the corresonding 129 * Java wrapper class instead, such as <code>java.lang.Boolean</code> 130 * for a <code>boolean</code> parameter) 131 * 132 * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 133 * Use {@link #CallMethodRule(String methodName,int paramCount, String [] paramTypes)} instead. 134 */ 135 public CallMethodRule(Digester digester, String methodName, 136 int paramCount, String paramTypes[]) { 137 138 this(methodName, paramCount, paramTypes); 139 140 } 141 142 143 /** 144 * Construct a "call method" rule with the specified method name. 145 * 146 * @param digester The associated Digester 147 * @param methodName Method name of the parent method to call 148 * @param paramCount The number of parameters to collect, or 149 * zero for a single argument from the body of ths element 150 * @param paramTypes The Java classes that represent the 151 * parameter types of the method arguments 152 * (if you wish to use a primitive type, specify the corresonding 153 * Java wrapper class instead, such as <code>java.lang.Boolean.TYPE</code> 154 * for a <code>boolean</code> parameter) 155 * 156 * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 157 * Use {@link #CallMethodRule(String methodName,int paramCount, Class [] paramTypes)} instead. 158 */ 159 public CallMethodRule(Digester digester, String methodName, 160 int paramCount, Class paramTypes[]) { 161 162 this(methodName, paramCount, paramTypes); 163 } 164 165 166 /** 167 * Construct a "call method" rule with the specified method name. The 168 * parameter types (if any) default to java.lang.String. 169 * 170 * @param methodName Method name of the parent method to call 171 * @param paramCount The number of parameters to collect, or 172 * zero for a single argument from the body of this element. 173 */ 174 public CallMethodRule(String methodName, 175 int paramCount) { 176 this(0, methodName, paramCount); 177 } 178 179 /** 180 * Construct a "call method" rule with the specified method name. The 181 * parameter types (if any) default to java.lang.String. 182 * 183 * @param targetOffset location of the target object. Positive numbers are 184 * relative to the top of the digester object stack. Negative numbers 185 * are relative to the bottom of the stack. Zero implies the top 186 * object on the stack. 187 * @param methodName Method name of the parent method to call 188 * @param paramCount The number of parameters to collect, or 189 * zero for a single argument from the body of this element. 190 */ 191 public CallMethodRule(int targetOffset, 192 String methodName, 193 int paramCount) { 194 195 this.targetOffset = targetOffset; 196 this.methodName = methodName; 197 this.paramCount = paramCount; 198 if (paramCount == 0) { 199 this.paramTypes = new Class[] { String.class }; 200 } else { 201 this.paramTypes = new Class[paramCount]; 202 for (int i = 0; i < this.paramTypes.length; i++) { 203 this.paramTypes[i] = String.class; 204 } 205 } 206 207 } 208 209 /** 210 * Construct a "call method" rule with the specified method name. 211 * The method should accept no parameters. 212 * 213 * @param methodName Method name of the parent method to call 214 */ 215 public CallMethodRule(String methodName) { 216 217 this(0, methodName, 0, (Class[]) null); 218 219 } 220 221 222 /** 223 * Construct a "call method" rule with the specified method name. 224 * The method should accept no parameters. 225 * 226 * @param targetOffset location of the target object. Positive numbers are 227 * relative to the top of the digester object stack. Negative numbers 228 * are relative to the bottom of the stack. Zero implies the top 229 * object on the stack. 230 * @param methodName Method name of the parent method to call 231 */ 232 public CallMethodRule(int targetOffset, String methodName) { 233 234 this(targetOffset, methodName, 0, (Class[]) null); 235 236 } 237 238 239 /** 240 * Construct a "call method" rule with the specified method name and 241 * parameter types. If <code>paramCount</code> is set to zero the rule 242 * will use the body of this element as the single argument of the 243 * method, unless <code>paramTypes</code> is null or empty, in this 244 * case the rule will call the specified method with no arguments. 245 * 246 * @param methodName Method name of the parent method to call 247 * @param paramCount The number of parameters to collect, or 248 * zero for a single argument from the body of ths element 249 * @param paramTypes The Java class names of the arguments 250 * (if you wish to use a primitive type, specify the corresonding 251 * Java wrapper class instead, such as <code>java.lang.Boolean</code> 252 * for a <code>boolean</code> parameter) 253 */ 254 public CallMethodRule( 255 String methodName, 256 int paramCount, 257 String paramTypes[]) { 258 this(0, methodName, paramCount, paramTypes); 259 } 260 261 /** 262 * Construct a "call method" rule with the specified method name and 263 * parameter types. If <code>paramCount</code> is set to zero the rule 264 * will use the body of this element as the single argument of the 265 * method, unless <code>paramTypes</code> is null or empty, in this 266 * case the rule will call the specified method with no arguments. 267 * 268 * @param targetOffset location of the target object. Positive numbers are 269 * relative to the top of the digester object stack. Negative numbers 270 * are relative to the bottom of the stack. Zero implies the top 271 * object on the stack. 272 * @param methodName Method name of the parent method to call 273 * @param paramCount The number of parameters to collect, or 274 * zero for a single argument from the body of ths element 275 * @param paramTypes The Java class names of the arguments 276 * (if you wish to use a primitive type, specify the corresonding 277 * Java wrapper class instead, such as <code>java.lang.Boolean</code> 278 * for a <code>boolean</code> parameter) 279 */ 280 public CallMethodRule( int targetOffset, 281 String methodName, 282 int paramCount, 283 String paramTypes[]) { 284 285 this.targetOffset = targetOffset; 286 this.methodName = methodName; 287 this.paramCount = paramCount; 288 if (paramTypes == null) { 289 this.paramTypes = new Class[paramCount]; 290 for (int i = 0; i < this.paramTypes.length; i++) { 291 this.paramTypes[i] = String.class; 292 } 293 } else { 294 // copy the parameter class names into an array 295 // the classes will be loaded when the digester is set 296 this.paramClassNames = new String[paramTypes.length]; 297 for (int i = 0; i < this.paramClassNames.length; i++) { 298 this.paramClassNames[i] = paramTypes[i]; 299 } 300 } 301 302 } 303 304 305 /** 306 * Construct a "call method" rule with the specified method name and 307 * parameter types. If <code>paramCount</code> is set to zero the rule 308 * will use the body of this element as the single argument of the 309 * method, unless <code>paramTypes</code> is null or empty, in this 310 * case the rule will call the specified method with no arguments. 311 * 312 * @param methodName Method name of the parent method to call 313 * @param paramCount The number of parameters to collect, or 314 * zero for a single argument from the body of ths element 315 * @param paramTypes The Java classes that represent the 316 * parameter types of the method arguments 317 * (if you wish to use a primitive type, specify the corresonding 318 * Java wrapper class instead, such as <code>java.lang.Boolean.TYPE</code> 319 * for a <code>boolean</code> parameter) 320 */ 321 public CallMethodRule( 322 String methodName, 323 int paramCount, 324 Class paramTypes[]) { 325 this(0, methodName, paramCount, paramTypes); 326 } 327 328 /** 329 * Construct a "call method" rule with the specified method name and 330 * parameter types. If <code>paramCount</code> is set to zero the rule 331 * will use the body of this element as the single argument of the 332 * method, unless <code>paramTypes</code> is null or empty, in this 333 * case the rule will call the specified method with no arguments. 334 * 335 * @param targetOffset location of the target object. Positive numbers are 336 * relative to the top of the digester object stack. Negative numbers 337 * are relative to the bottom of the stack. Zero implies the top 338 * object on the stack. 339 * @param methodName Method name of the parent method to call 340 * @param paramCount The number of parameters to collect, or 341 * zero for a single argument from the body of ths element 342 * @param paramTypes The Java classes that represent the 343 * parameter types of the method arguments 344 * (if you wish to use a primitive type, specify the corresonding 345 * Java wrapper class instead, such as <code>java.lang.Boolean.TYPE</code> 346 * for a <code>boolean</code> parameter) 347 */ 348 public CallMethodRule( int targetOffset, 349 String methodName, 350 int paramCount, 351 Class paramTypes[]) { 352 353 this.targetOffset = targetOffset; 354 this.methodName = methodName; 355 this.paramCount = paramCount; 356 if (paramTypes == null) { 357 this.paramTypes = new Class[paramCount]; 358 for (int i = 0; i < this.paramTypes.length; i++) { 359 this.paramTypes[i] = String.class; 360 } 361 } else { 362 this.paramTypes = new Class[paramTypes.length]; 363 for (int i = 0; i < this.paramTypes.length; i++) { 364 this.paramTypes[i] = paramTypes[i]; 365 } 366 } 367 368 } 369 370 371 // ----------------------------------------------------- Instance Variables 372 373 374 /** 375 * The body text collected from this element. 376 */ 377 protected String bodyText = null; 378 379 380 /** 381 * location of the target object for the call, relative to the 382 * top of the digester object stack. The default value of zero 383 * means the target object is the one on top of the stack. 384 */ 385 protected int targetOffset = 0; 386 387 /** 388 * The method name to call on the parent object. 389 */ 390 protected String methodName = null; 391 392 393 /** 394 * The number of parameters to collect from <code>MethodParam</code> rules. 395 * If this value is zero, a single parameter will be collected from the 396 * body of this element. 397 */ 398 protected int paramCount = 0; 399 400 401 /** 402 * The parameter types of the parameters to be collected. 403 */ 404 protected Class paramTypes[] = null; 405 406 /** 407 * The names of the classes of the parameters to be collected. 408 * This attribute allows creation of the classes to be postponed until the digester is set. 409 */ 410 private String paramClassNames[] = null; 411 412 /** 413 * Should <code>MethodUtils.invokeExactMethod</code> be used for reflection. 414 */ 415 protected boolean useExactMatch = false; 416 417 // --------------------------------------------------------- Public Methods 418 419 /** 420 * Should <code>MethodUtils.invokeExactMethod</code> 421 * be used for the reflection. 422 */ 423 public boolean getUseExactMatch() { 424 return useExactMatch; 425 } 426 427 /** 428 * Set whether <code>MethodUtils.invokeExactMethod</code> 429 * should be used for the reflection. 430 */ 431 public void setUseExactMatch(boolean useExactMatch) 432 { 433 this.useExactMatch = useExactMatch; 434 } 435 436 /** 437 * Set the associated digester. 438 * If needed, this class loads the parameter classes from their names. 439 */ 440 public void setDigester(Digester digester) 441 { 442 // call superclass 443 super.setDigester(digester); 444 // if necessary, load parameter classes 445 if (this.paramClassNames != null) { 446 this.paramTypes = new Class[paramClassNames.length]; 447 for (int i = 0; i < this.paramClassNames.length; i++) { 448 try { 449 this.paramTypes[i] = 450 digester.getClassLoader().loadClass(this.paramClassNames[i]); 451 } catch (ClassNotFoundException e) { 452 // use the digester log 453 digester.getLogger().error("(CallMethodRule) Cannot load class " + this.paramClassNames[i], e); 454 this.paramTypes[i] = null; // Will cause NPE later 455 } 456 } 457 } 458 } 459 460 /** 461 * Process the start of this element. 462 * 463 * @param attributes The attribute list for this element 464 */ 465 public void begin(Attributes attributes) throws Exception { 466 467 // Push an array to capture the parameter values if necessary 468 if (paramCount > 0) { 469 Object parameters[] = new Object[paramCount]; 470 for (int i = 0; i < parameters.length; i++) { 471 parameters[i] = null; 472 } 473 digester.pushParams(parameters); 474 } 475 476 } 477 478 479 /** 480 * Process the body text of this element. 481 * 482 * @param bodyText The body text of this element 483 */ 484 public void body(String bodyText) throws Exception { 485 486 if (paramCount == 0) { 487 this.bodyText = bodyText.trim(); 488 } 489 490 } 491 492 493 /** 494 * Process the end of this element. 495 */ 496 public void end() throws Exception { 497 498 // Retrieve or construct the parameter values array 499 Object parameters[] = null; 500 if (paramCount > 0) { 501 502 parameters = (Object[]) digester.popParams(); 503 504 if (digester.log.isTraceEnabled()) { 505 for (int i=0,size=parameters.length;i<size;i++) { 506 digester.log.trace("[CallMethodRule](" + i + ")" + parameters[i]) ; 507 } 508 } 509 510 // In the case where the target method takes a single parameter 511 // and that parameter does not exist (the CallParamRule never 512 // executed or the CallParamRule was intended to set the parameter 513 // from an attribute but the attribute wasn't present etc) then 514 // skip the method call. 515 // 516 // This is useful when a class has a "default" value that should 517 // only be overridden if data is present in the XML. I don't 518 // know why this should only apply to methods taking *one* 519 // parameter, but it always has been so we can't change it now. 520 if (paramCount == 1 && parameters[0] == null) { 521 return; 522 } 523 524 } else if (paramTypes != null && paramTypes.length != 0) { 525 // Having paramCount == 0 and paramTypes.length == 1 indicates 526 // that we have the special case where the target method has one 527 // parameter being the body text of the current element. 528 529 // There is no body text included in the source XML file, 530 // so skip the method call 531 if (bodyText == null) { 532 return; 533 } 534 535 parameters = new Object[1]; 536 parameters[0] = bodyText; 537 if (paramTypes.length == 0) { 538 paramTypes = new Class[1]; 539 paramTypes[0] = String.class; 540 } 541 542 } else { 543 // When paramCount is zero and paramTypes.length is zero it 544 // means that we truly are calling a method with no parameters. 545 // Nothing special needs to be done here. 546 ; 547 } 548 549 // Construct the parameter values array we will need 550 // We only do the conversion if the param value is a String and 551 // the specified paramType is not String. 552 Object paramValues[] = new Object[paramTypes.length]; 553 for (int i = 0; i < paramTypes.length; i++) { 554 // convert nulls and convert stringy parameters 555 // for non-stringy param types 556 if( 557 parameters[i] == null || 558 (parameters[i] instanceof String && 559 !String.class.isAssignableFrom(paramTypes[i]))) { 560 561 paramValues[i] = 562 ConvertUtils.convert((String) parameters[i], paramTypes[i]); 563 } else { 564 paramValues[i] = parameters[i]; 565 } 566 } 567 568 // Determine the target object for the method call 569 Object target; 570 if (targetOffset >= 0) { 571 target = digester.peek(targetOffset); 572 } else { 573 target = digester.peek( digester.getCount() + targetOffset ); 574 } 575 576 if (target == null) { 577 StringBuffer sb = new StringBuffer(); 578 sb.append("[CallMethodRule]{"); 579 sb.append(digester.match); 580 sb.append("} Call target is null ("); 581 sb.append("targetOffset="); 582 sb.append(targetOffset); 583 sb.append(",stackdepth="); 584 sb.append(digester.getCount()); 585 sb.append(")"); 586 throw new org.xml.sax.SAXException(sb.toString()); 587 } 588 589 // Invoke the required method on the top object 590 if (digester.log.isDebugEnabled()) { 591 StringBuffer sb = new StringBuffer("[CallMethodRule]{"); 592 sb.append(digester.match); 593 sb.append("} Call "); 594 sb.append(target.getClass().getName()); 595 sb.append("."); 596 sb.append(methodName); 597 sb.append("("); 598 for (int i = 0; i < paramValues.length; i++) { 599 if (i > 0) { 600 sb.append(","); 601 } 602 if (paramValues[i] == null) { 603 sb.append("null"); 604 } else { 605 sb.append(paramValues[i].toString()); 606 } 607 sb.append("/"); 608 if (paramTypes[i] == null) { 609 sb.append("null"); 610 } else { 611 sb.append(paramTypes[i].getName()); 612 } 613 } 614 sb.append(")"); 615 digester.log.debug(sb.toString()); 616 } 617 618 Object result = null; 619 if (useExactMatch) { 620 // invoke using exact match 621 result = MethodUtils.invokeExactMethod(target, methodName, 622 paramValues, paramTypes); 623 624 } else { 625 // invoke using fuzzier match 626 result = MethodUtils.invokeMethod(target, methodName, 627 paramValues, paramTypes); 628 } 629 630 processMethodCallResult(result); 631 } 632 633 634 /** 635 * Clean up after parsing is complete. 636 */ 637 public void finish() throws Exception { 638 639 bodyText = null; 640 641 } 642 643 /** 644 * Subclasses may override this method to perform additional processing of the 645 * invoked method's result. 646 * 647 * @param result the Object returned by the method invoked, possibly null 648 */ 649 protected void processMethodCallResult(Object result) { 650 // do nothing 651 } 652 653 /** 654 * Render a printable version of this Rule. 655 */ 656 public String toString() { 657 658 StringBuffer sb = new StringBuffer("CallMethodRule["); 659 sb.append("methodName="); 660 sb.append(methodName); 661 sb.append(", paramCount="); 662 sb.append(paramCount); 663 sb.append(", paramTypes={"); 664 if (paramTypes != null) { 665 for (int i = 0; i < paramTypes.length; i++) { 666 if (i > 0) { 667 sb.append(", "); 668 } 669 sb.append(paramTypes[i].getName()); 670 } 671 } 672 sb.append("}"); 673 sb.append("]"); 674 return (sb.toString()); 675 676 } 677 678 679 }