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/* $Id: CallMethodRule.java 729106 2008-12-23 20:48:09Z rahul $
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.digester;
import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.MethodUtils;
import org.xml.sax.Attributes;
/**
* Rule implementation that calls a method on an object on the stack
* (normally the top/parent object), passing arguments collected from
* subsequent CallParamRule rules or from the body of this
* element.
*
* By using {@link #CallMethodRule(String methodName)}
* a method call can be made to a method which accepts no
* arguments.
*
* Incompatible method parameter types are converted
* using org.apache.commons.beanutils.ConvertUtils.
*
*
* This rule now uses {@link MethodUtils#invokeMethod} by default.
* This increases the kinds of methods successfully and allows primitives
* to be matched by passing in wrapper classes.
* There are rare cases when {@link MethodUtils#invokeExactMethod}
* (the old default) is required.
* This method is much stricter in it's reflection.
* Setting the UseExactMatch to true reverts to the use of this
* method.
*
* Note that the target method is invoked when the end of
* the tag the CallMethodRule fired on is encountered, not when the
* last parameter becomes available. This implies that rules which fire on
* tags nested within the one associated with the CallMethodRule will
* fire before the CallMethodRule invokes the target method. This behaviour is
* not configurable.
*
* Note also that if a CallMethodRule is expecting exactly one parameter
* and that parameter is not available (eg CallParamRule is used with an
* attribute name but the attribute does not exist) then the method will
* not be invoked. If a CallMethodRule is expecting more than one parameter,
* then it is always invoked, regardless of whether the parameters were
* available or not; missing parameters are converted to the appropriate target
* type by calling ConvertUtils.convert. Note that the default ConvertUtils
* converters for the String type returns a null when passed a null, meaning
* that CallMethodRule will passed null for all String parameters for which
* there is no parameter info available from the XML. However parameters of
* type Float and Integer will be passed a real object containing a zero value
* as that is the output of the default ConvertUtils converters for those
* types when passed a null. You can register custom converters to change
* this behaviour; see the beautils library documentation for more info.
*
* Note that when a constructor is used with paramCount=0, indicating that
* the body of the element is to be passed to the target method, an empty
* element will cause an empty string to be passed to the target method,
* not null. And if automatic type conversion is being applied (ie if the
* target function takes something other than a string as a parameter) then
* the conversion will fail if the converter class does not accept an empty
* string as valid input.
*
* CallMethodRule has a design flaw which can cause it to fail under
* certain rule configurations. All CallMethodRule instances share a single
* parameter stack, and all CallParamRule instances simply store their data
* into the parameter-info structure that is on the top of the stack. This
* means that two CallMethodRule instances cannot be associated with the
* same pattern without getting scrambled parameter data. This same issue
* also applies when a CallMethodRule matches some element X, a different
* CallMethodRule matches a child element Y and some of the CallParamRules
* associated with the first CallMethodRule match element Y or one of its
* child elements. This issue has been present since the very first release
* of Digester. Note, however, that this configuration of CallMethodRule
* instances is not commonly required.
*/
public class CallMethodRule extends Rule {
// ----------------------------------------------------------- Constructors
/**
* Construct a "call method" rule with the specified method name. The
* parameter types (if any) default to java.lang.String.
*
* @param digester The associated Digester
* @param methodName Method name of the parent method to call
* @param paramCount The number of parameters to collect, or
* zero for a single argument from the body of this element.
*
*
* @deprecated The digester instance is now set in the {@link Digester#addRule} method.
* Use {@link #CallMethodRule(String methodName,int paramCount)} instead.
*/
public CallMethodRule(Digester digester, String methodName,
int paramCount) {
this(methodName, paramCount);
}
/**
* Construct a "call method" rule with the specified method name.
*
* @param digester The associated Digester
* @param methodName Method name of the parent method to call
* @param paramCount The number of parameters to collect, or
* zero for a single argument from the body of ths element
* @param paramTypes The Java class names of the arguments
* (if you wish to use a primitive type, specify the corresonding
* Java wrapper class instead, such as java.lang.Boolean
* for a boolean parameter)
*
* @deprecated The digester instance is now set in the {@link Digester#addRule} method.
* Use {@link #CallMethodRule(String methodName,int paramCount, String [] paramTypes)} instead.
*/
public CallMethodRule(Digester digester, String methodName,
int paramCount, String paramTypes[]) {
this(methodName, paramCount, paramTypes);
}
/**
* Construct a "call method" rule with the specified method name.
*
* @param digester The associated Digester
* @param methodName Method name of the parent method to call
* @param paramCount The number of parameters to collect, or
* zero for a single argument from the body of ths element
* @param paramTypes The Java classes that represent the
* parameter types of the method arguments
* (if you wish to use a primitive type, specify the corresonding
* Java wrapper class instead, such as java.lang.Boolean.TYPE
* for a boolean parameter)
*
* @deprecated The digester instance is now set in the {@link Digester#addRule} method.
* Use {@link #CallMethodRule(String methodName,int paramCount, Class [] paramTypes)} instead.
*/
public CallMethodRule(Digester digester, String methodName,
int paramCount, Class paramTypes[]) {
this(methodName, paramCount, paramTypes);
}
/**
* Construct a "call method" rule with the specified method name. The
* parameter types (if any) default to java.lang.String.
*
* @param methodName Method name of the parent method to call
* @param paramCount The number of parameters to collect, or
* zero for a single argument from the body of this element.
*/
public CallMethodRule(String methodName,
int paramCount) {
this(0, methodName, paramCount);
}
/**
* Construct a "call method" rule with the specified method name. The
* parameter types (if any) default to java.lang.String.
*
* @param targetOffset location of the target object. Positive numbers are
* relative to the top of the digester object stack. Negative numbers
* are relative to the bottom of the stack. Zero implies the top
* object on the stack.
* @param methodName Method name of the parent method to call
* @param paramCount The number of parameters to collect, or
* zero for a single argument from the body of this element.
*/
public CallMethodRule(int targetOffset,
String methodName,
int paramCount) {
this.targetOffset = targetOffset;
this.methodName = methodName;
this.paramCount = paramCount;
if (paramCount == 0) {
this.paramTypes = new Class[] { String.class };
} else {
this.paramTypes = new Class[paramCount];
for (int i = 0; i < this.paramTypes.length; i++) {
this.paramTypes[i] = String.class;
}
}
}
/**
* Construct a "call method" rule with the specified method name.
* The method should accept no parameters.
*
* @param methodName Method name of the parent method to call
*/
public CallMethodRule(String methodName) {
this(0, methodName, 0, (Class[]) null);
}
/**
* Construct a "call method" rule with the specified method name.
* The method should accept no parameters.
*
* @param targetOffset location of the target object. Positive numbers are
* relative to the top of the digester object stack. Negative numbers
* are relative to the bottom of the stack. Zero implies the top
* object on the stack.
* @param methodName Method name of the parent method to call
*/
public CallMethodRule(int targetOffset, String methodName) {
this(targetOffset, methodName, 0, (Class[]) null);
}
/**
* Construct a "call method" rule with the specified method name and
* parameter types. If paramCount is set to zero the rule
* will use the body of this element as the single argument of the
* method, unless paramTypes is null or empty, in this
* case the rule will call the specified method with no arguments.
*
* @param methodName Method name of the parent method to call
* @param paramCount The number of parameters to collect, or
* zero for a single argument from the body of ths element
* @param paramTypes The Java class names of the arguments
* (if you wish to use a primitive type, specify the corresonding
* Java wrapper class instead, such as java.lang.Boolean
* for a boolean parameter)
*/
public CallMethodRule(
String methodName,
int paramCount,
String paramTypes[]) {
this(0, methodName, paramCount, paramTypes);
}
/**
* Construct a "call method" rule with the specified method name and
* parameter types. If paramCount is set to zero the rule
* will use the body of this element as the single argument of the
* method, unless paramTypes is null or empty, in this
* case the rule will call the specified method with no arguments.
*
* @param targetOffset location of the target object. Positive numbers are
* relative to the top of the digester object stack. Negative numbers
* are relative to the bottom of the stack. Zero implies the top
* object on the stack.
* @param methodName Method name of the parent method to call
* @param paramCount The number of parameters to collect, or
* zero for a single argument from the body of ths element
* @param paramTypes The Java class names of the arguments
* (if you wish to use a primitive type, specify the corresonding
* Java wrapper class instead, such as java.lang.Boolean
* for a boolean parameter)
*/
public CallMethodRule( int targetOffset,
String methodName,
int paramCount,
String paramTypes[]) {
this.targetOffset = targetOffset;
this.methodName = methodName;
this.paramCount = paramCount;
if (paramTypes == null) {
this.paramTypes = new Class[paramCount];
for (int i = 0; i < this.paramTypes.length; i++) {
this.paramTypes[i] = String.class;
}
} else {
// copy the parameter class names into an array
// the classes will be loaded when the digester is set
this.paramClassNames = new String[paramTypes.length];
for (int i = 0; i < this.paramClassNames.length; i++) {
this.paramClassNames[i] = paramTypes[i];
}
}
}
/**
* Construct a "call method" rule with the specified method name and
* parameter types. If paramCount is set to zero the rule
* will use the body of this element as the single argument of the
* method, unless paramTypes is null or empty, in this
* case the rule will call the specified method with no arguments.
*
* @param methodName Method name of the parent method to call
* @param paramCount The number of parameters to collect, or
* zero for a single argument from the body of ths element
* @param paramTypes The Java classes that represent the
* parameter types of the method arguments
* (if you wish to use a primitive type, specify the corresonding
* Java wrapper class instead, such as java.lang.Boolean.TYPE
* for a boolean parameter)
*/
public CallMethodRule(
String methodName,
int paramCount,
Class paramTypes[]) {
this(0, methodName, paramCount, paramTypes);
}
/**
* Construct a "call method" rule with the specified method name and
* parameter types. If paramCount is set to zero the rule
* will use the body of this element as the single argument of the
* method, unless paramTypes is null or empty, in this
* case the rule will call the specified method with no arguments.
*
* @param targetOffset location of the target object. Positive numbers are
* relative to the top of the digester object stack. Negative numbers
* are relative to the bottom of the stack. Zero implies the top
* object on the stack.
* @param methodName Method name of the parent method to call
* @param paramCount The number of parameters to collect, or
* zero for a single argument from the body of ths element
* @param paramTypes The Java classes that represent the
* parameter types of the method arguments
* (if you wish to use a primitive type, specify the corresonding
* Java wrapper class instead, such as java.lang.Boolean.TYPE
* for a boolean parameter)
*/
public CallMethodRule( int targetOffset,
String methodName,
int paramCount,
Class paramTypes[]) {
this.targetOffset = targetOffset;
this.methodName = methodName;
this.paramCount = paramCount;
if (paramTypes == null) {
this.paramTypes = new Class[paramCount];
for (int i = 0; i < this.paramTypes.length; i++) {
this.paramTypes[i] = String.class;
}
} else {
this.paramTypes = new Class[paramTypes.length];
for (int i = 0; i < this.paramTypes.length; i++) {
this.paramTypes[i] = paramTypes[i];
}
}
}
// ----------------------------------------------------- Instance Variables
/**
* The body text collected from this element.
*/
protected String bodyText = null;
/**
* location of the target object for the call, relative to the
* top of the digester object stack. The default value of zero
* means the target object is the one on top of the stack.
*/
protected int targetOffset = 0;
/**
* The method name to call on the parent object.
*/
protected String methodName = null;
/**
* The number of parameters to collect from MethodParam rules.
* If this value is zero, a single parameter will be collected from the
* body of this element.
*/
protected int paramCount = 0;
/**
* The parameter types of the parameters to be collected.
*/
protected Class paramTypes[] = null;
/**
* The names of the classes of the parameters to be collected.
* This attribute allows creation of the classes to be postponed until the digester is set.
*/
private String paramClassNames[] = null;
/**
* Should MethodUtils.invokeExactMethod be used for reflection.
*/
protected boolean useExactMatch = false;
// --------------------------------------------------------- Public Methods
/**
* Should MethodUtils.invokeExactMethod
* be used for the reflection.
*/
public boolean getUseExactMatch() {
return useExactMatch;
}
/**
* Set whether MethodUtils.invokeExactMethod
* should be used for the reflection.
*/
public void setUseExactMatch(boolean useExactMatch)
{
this.useExactMatch = useExactMatch;
}
/**
* Set the associated digester.
* If needed, this class loads the parameter classes from their names.
*/
public void setDigester(Digester digester)
{
// call superclass
super.setDigester(digester);
// if necessary, load parameter classes
if (this.paramClassNames != null) {
this.paramTypes = new Class[paramClassNames.length];
for (int i = 0; i < this.paramClassNames.length; i++) {
try {
this.paramTypes[i] =
digester.getClassLoader().loadClass(this.paramClassNames[i]);
} catch (ClassNotFoundException e) {
// use the digester log
digester.getLogger().error("(CallMethodRule) Cannot load class " + this.paramClassNames[i], e);
this.paramTypes[i] = null; // Will cause NPE later
}
}
}
}
/**
* Process the start of this element.
*
* @param attributes The attribute list for this element
*/
public void begin(Attributes attributes) throws Exception {
// Push an array to capture the parameter values if necessary
if (paramCount > 0) {
Object parameters[] = new Object[paramCount];
for (int i = 0; i < parameters.length; i++) {
parameters[i] = null;
}
digester.pushParams(parameters);
}
}
/**
* Process the body text of this element.
*
* @param bodyText The body text of this element
*/
public void body(String bodyText) throws Exception {
if (paramCount == 0) {
this.bodyText = bodyText.trim();
}
}
/**
* Process the end of this element.
*/
public void end() throws Exception {
// Retrieve or construct the parameter values array
Object parameters[] = null;
if (paramCount > 0) {
parameters = (Object[]) digester.popParams();
if (digester.log.isTraceEnabled()) {
for (int i=0,size=parameters.length;i= 0) {
target = digester.peek(targetOffset);
} else {
target = digester.peek( digester.getCount() + targetOffset );
}
if (target == null) {
StringBuffer sb = new StringBuffer();
sb.append("[CallMethodRule]{");
sb.append(digester.match);
sb.append("} Call target is null (");
sb.append("targetOffset=");
sb.append(targetOffset);
sb.append(",stackdepth=");
sb.append(digester.getCount());
sb.append(")");
throw new org.xml.sax.SAXException(sb.toString());
}
// Invoke the required method on the top object
if (digester.log.isDebugEnabled()) {
StringBuffer sb = new StringBuffer("[CallMethodRule]{");
sb.append(digester.match);
sb.append("} Call ");
sb.append(target.getClass().getName());
sb.append(".");
sb.append(methodName);
sb.append("(");
for (int i = 0; i < paramValues.length; i++) {
if (i > 0) {
sb.append(",");
}
if (paramValues[i] == null) {
sb.append("null");
} else {
sb.append(paramValues[i].toString());
}
sb.append("/");
if (paramTypes[i] == null) {
sb.append("null");
} else {
sb.append(paramTypes[i].getName());
}
}
sb.append(")");
digester.log.debug(sb.toString());
}
Object result = null;
if (useExactMatch) {
// invoke using exact match
result = MethodUtils.invokeExactMethod(target, methodName,
paramValues, paramTypes);
} else {
// invoke using fuzzier match
result = MethodUtils.invokeMethod(target, methodName,
paramValues, paramTypes);
}
processMethodCallResult(result);
}
/**
* Clean up after parsing is complete.
*/
public void finish() throws Exception {
bodyText = null;
}
/**
* Subclasses may override this method to perform additional processing of the
* invoked method's result.
*
* @param result the Object returned by the method invoked, possibly null
*/
protected void processMethodCallResult(Object result) {
// do nothing
}
/**
* Render a printable version of this Rule.
*/
public String toString() {
StringBuffer sb = new StringBuffer("CallMethodRule[");
sb.append("methodName=");
sb.append(methodName);
sb.append(", paramCount=");
sb.append(paramCount);
sb.append(", paramTypes={");
if (paramTypes != null) {
for (int i = 0; i < paramTypes.length; i++) {
if (i > 0) {
sb.append(", ");
}
sb.append(paramTypes[i].getName());
}
}
sb.append("}");
sb.append("]");
return (sb.toString());
}
}
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