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Posted to commits@commons.apache.org by si...@apache.org on 2011/01/30 15:36:28 UTC
svn commit: r1065296 -
/commons/sandbox/digester3/trunk/src/main/java/org/apache/commons/digester3/CallMethodRule.java
Author: simonetripodi
Date: Sun Jan 30 14:36:27 2011
New Revision: 1065296
URL: http://svn.apache.org/viewvc?rev=1065296&view=rev
Log:
first checkin of CallMethodRule
Added:
commons/sandbox/digester3/trunk/src/main/java/org/apache/commons/digester3/CallMethodRule.java (with props)
Added: commons/sandbox/digester3/trunk/src/main/java/org/apache/commons/digester3/CallMethodRule.java
URL: http://svn.apache.org/viewvc/commons/sandbox/digester3/trunk/src/main/java/org/apache/commons/digester3/CallMethodRule.java?rev=1065296&view=auto
==============================================================================
--- commons/sandbox/digester3/trunk/src/main/java/org/apache/commons/digester3/CallMethodRule.java (added)
+++ commons/sandbox/digester3/trunk/src/main/java/org/apache/commons/digester3/CallMethodRule.java Sun Jan 30 14:36:27 2011
@@ -0,0 +1,351 @@
+/* $Id$
+ *
+ * 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.digester3;
+
+import java.util.Formatter;
+
+import org.apache.commons.beanutils.ConvertUtils;
+import org.apache.commons.beanutils.MethodUtils;
+import org.xml.sax.Attributes;
+
+/**
+ * <p>Rule implementation that calls a method on an object on the stack
+ * (normally the top/parent object), passing arguments collected from
+ * subsequent <code>CallParamRule</code> rules or from the body of this
+ * element. </p>
+ *
+ * <p>By using {@link #CallMethodRule(String methodName)}
+ * a method call can be made to a method which accepts no
+ * arguments.</p>
+ *
+ * <p>Incompatible method parameter types are converted
+ * using <code>org.apache.commons.beanutils.ConvertUtils</code>.
+ * </p>
+ *
+ * <p>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 <code>UseExactMatch</code> to true reverts to the use of this
+ * method.</p>
+ *
+ * <p>Note that the target method is invoked when the <i>end</i> of
+ * the tag the CallMethodRule fired on is encountered, <i>not</i> 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. </p>
+ *
+ * <p>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.</p>
+ *
+ * <p>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 <i>empty string</i> 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.</p>
+ *
+ * <p>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 this.getDigester(). Note, however, that this configuration of CallMethodRule
+ * instances is not commonly required.</p>
+ */
+public class CallMethodRule extends Rule {
+
+ /**
+ * 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.
+ */
+ private final int targetOffset;
+
+ /**
+ * The method name to call on the parent object.
+ */
+ private final String methodName;
+
+ /**
+ * The parameter types of the parameters to be collected.
+ */
+ private final Class<?> paramTypes[];
+
+ /**
+ * Should <code>MethodUtils.invokeExactMethod</code> be used for reflection.
+ */
+ private final boolean useExactMatch;
+
+ /**
+ * The body text collected from this element.
+ */
+ private String bodyText = null;
+
+ /**
+ * Construct a "call method" rule with the specified method name and
+ * parameter types. If <code>paramCount</code> is set to zero the rule
+ * will use the body of this element as the single argument of the
+ * method, unless <code>paramTypes</code> 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 <code>java.lang.Boolean.TYPE</code>
+ * for a <code>boolean</code> parameter)
+ * @param useExactMatch Should <code>MethodUtils.invokeExactMethod</code>
+ * be used for the reflection.
+ */
+ public CallMethodRule(int targetOffset, String methodName, int paramCount, Class<?>[] paramTypes, boolean useExactMatch) {
+ this.targetOffset = targetOffset;
+ this.methodName = methodName;
+
+ // copy the parameter class into an array
+ this.paramTypes = new Class[paramTypes.length];
+ System.arraycopy(paramTypes, 0, this.paramTypes, 0, paramTypes.length);
+
+ this.useExactMatch = useExactMatch;
+ }
+
+ /**
+ * Process the start of this element.
+ *
+ * @param attributes The attribute list for this element
+ */
+ @Override
+ public void begin(String namespace, String name, Attributes attributes) throws Exception {
+ // Push an array to capture the parameter values if necessary
+ if (this.paramTypes.length > 0) {
+ Object parameters[] = new Object[this.paramTypes.length];
+ for (int i = 0; i < parameters.length; i++) {
+ parameters[i] = null;
+ }
+ this.getDigester().pushParams(parameters);
+ }
+ }
+
+ /**
+ * Process the body text of this element.
+ *
+ * @param bodyText The body text of this element
+ */
+ @Override
+ public void body(String namespace, String name, String text) throws Exception {
+ if (this.paramTypes.length == 0) {
+ this.bodyText = text.trim();
+ }
+ }
+
+ /**
+ * Process the end of this element.
+ */
+ @Override
+ public void end(String namespace, String name) throws Exception {
+ // Retrieve or construct the parameter values array
+ Object parameters[] = null;
+ if (this.paramTypes.length > 0) {
+
+ parameters = (Object[]) this.getDigester().popParams();
+
+ if (this.getDigester().getLog().isTraceEnabled()) {
+ Formatter formatter = new Formatter("[CallMethodRule]");
+
+ for (int i = 0, size = parameters.length; i < size; i++) {
+ if (i > 0) {
+ formatter.format(", ");
+ }
+ formatter.format("(%s) %s", i, parameters[i]);
+ }
+
+ this.getDigester().getLog().trace(formatter.toString());
+ }
+
+ // In the case where the target method takes a single parameter
+ // and that parameter does not exist (the CallParamRule never
+ // executed or the CallParamRule was intended to set the parameter
+ // from an attribute but the attribute wasn't present etc) then
+ // skip the method call.
+ //
+ // This is useful when a class has a "default" value that should
+ // only be overridden if data is present in the XML. I don't
+ // know why this should only apply to methods taking *one*
+ // parameter, but it always has been so we can't change it now.
+ if (this.paramTypes.length == 1 && parameters[0] == null) {
+ return;
+ }
+
+ } else if (this.paramTypes != null && this.paramTypes.length != 0) {
+ // Having paramCount == 0 and paramTypes.length == 1 indicates
+ // that we have the special case where the target method has one
+ // parameter being the body text of the current element.
+
+ // There is no body text included in the source XML file,
+ // so skip the method call
+ if (this.bodyText == null) {
+ return;
+ }
+
+ parameters = new Object[]{ this.bodyText };
+ /* TODO this situation has to be managed by the builder
+ if (this.paramTypes.length == 0) {
+ this.paramTypes = new Class[1];
+ this.paramTypes[0] = String.class;
+ } */
+
+ } else {
+ // When paramCount is zero and paramTypes.length is zero it
+ // means that we truly are calling a method with no parameters.
+ // Nothing special needs to be done here.
+ }
+
+ // Construct the parameter values array we will need
+ // We only do the conversion if the param value is a String and
+ // the specified paramType is not String.
+ Object paramValues[] = new Object[this.paramTypes.length];
+ for (int i = 0; i < this.paramTypes.length; i++) {
+ // convert nulls and convert stringy parameters
+ // for non-stringy param types
+ if (parameters[i] == null
+ || (parameters[i] instanceof String
+ && !String.class.isAssignableFrom(this.paramTypes[i]))) {
+
+ paramValues[i] = ConvertUtils.convert((String) parameters[i], this.paramTypes[i]);
+ } else {
+ paramValues[i] = parameters[i];
+ }
+ }
+
+ // Determine the target object for the method call
+ Object target;
+ if (this.targetOffset >= 0) {
+ target = this.getDigester().peek(this.targetOffset);
+ } else {
+ target = this.getDigester().peek(this.getDigester().getCount() + this.targetOffset);
+ }
+
+ if (target == null) {
+ throw new org.xml.sax.SAXException(
+ String.format("[CallMethodRule]{%s} Call target is null (targetOffset=%s, stackdepth=%s)",
+ this.getDigester().getMatch(),
+ this.targetOffset,
+ this.getDigester().getCount()));
+ }
+
+ // Invoke the required method on the top object
+ if (this.getDigester().getLog().isDebugEnabled()) {
+ Formatter formatter = new Formatter()
+ .format("[CallMethodRule]{%s} Call %s.%s(",
+ this.getDigester().getMatch(),
+ target.getClass().getName(),
+ this.methodName);
+
+ for (int i = 0; i < paramValues.length; i++) {
+ if (i > 0) {
+ formatter.format(", ");
+ }
+
+ formatter.format("%s/%s",
+ (paramValues[i] == null ? "null" : paramValues[i].toString()),
+ (this.paramTypes[i] == null ? "null" : this.paramTypes[i].getName()));
+ }
+
+ formatter.format(")");
+ this.getDigester().getLog().debug(formatter.toString());
+ }
+
+ Object result = null;
+ if (this.useExactMatch) {
+ // invoke using exact match
+ result = MethodUtils.invokeExactMethod(target, this.methodName, paramValues, this.paramTypes);
+ } else {
+ // invoke using fuzzier match
+ result = MethodUtils.invokeMethod(target, this.methodName, paramValues, this.paramTypes);
+ }
+
+ processMethodCallResult(result);
+ }
+
+ /**
+ * Clean up after parsing is complete.
+ */
+ @Override
+ public void finish() throws Exception {
+ this.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.
+ */
+ @Override
+ public String toString() {
+ Formatter formatter = new Formatter().format("CallMethodRule[methodName=%s, paramCount=%s, paramTypes={",
+ this.methodName,
+ this.paramTypes.length);
+
+ if (this.paramTypes != null) {
+ for (int i = 0; i < this.paramTypes.length; i++) {
+ if (i > 0) {
+ formatter.format(", ");
+ }
+ formatter.format(this.paramTypes[i].getName());
+ }
+ }
+
+ return formatter.format("}]").toString();
+ }
+
+}
Propchange: commons/sandbox/digester3/trunk/src/main/java/org/apache/commons/digester3/CallMethodRule.java
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