http://commons.apache.org/digester/: The Digester package lets you configure an XML to Java object mapping module which triggers certain actions called rules whenever a particular pattern of nested XML elements is recognized. (The Apache Software Foundation)
  • Bradley M. Handy
  • Christopher Lenz
  • Ted Husted
  • David H. Martin
  • Henri Chen
  • Janek Bogucki
  • Mark Huisman
  • Paul Jack
  • Anton Maslovsky
  • Matt Cleveland
  • Gabriele Carcassi
  • Wendy Smoak
  • Kevin Ross
  • Craig McClanahan
  • Robert Burrell Donkin
  • Scott Sanders
  • James Strachan
  • Jason van Zyl
  • Tim OBrien
  • Jean-Francois Arcand
  • Simon Kitching
  • Rahul Akolkar
  • Simone Tripodi 
/* $Id: SetNextRule.java 992060 2010-09-02 19:09:47Z simonetripodi $
 *
 * 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.MethodUtils;



Rule implementation that calls a method on the (top-1) (parent)
object, passing the top object (child) as an argument.  It is
commonly used to establish parent-child relationships.


This rule now supports more flexible method matching by default. It is possible that this may break (some) code written against release 1.1.1 or earlier. See isExactMatch() for more details.
 

Note that while CallMethodRule uses commons-beanutils' data-conversion
functionality (ConvertUtils class) to convert parameter values into
the appropriate type for the parameter to the called method, this
rule does not. Needing to use ConvertUtils functionality when building
parent-child relationships is expected to be very rare; however if you 
do need this then instead of using this rule, create a CallMethodRule
specifying targetOffset of 1 in the constructor.


/**
 * <p>Rule implementation that calls a method on the (top-1) (parent)
 * object, passing the top object (child) as an argument.  It is
 * commonly used to establish parent-child relationships.</p>
 *
 * <p>This rule now supports more flexible method matching by default.
 * It is possible that this may break (some) code 
 * written against release 1.1.1 or earlier.
 * See {@link #isExactMatch()} for more details.</p> 
 *
 * <p>Note that while CallMethodRule uses commons-beanutils' data-conversion
 * functionality (ConvertUtils class) to convert parameter values into
 * the appropriate type for the parameter to the called method, this
 * rule does not. Needing to use ConvertUtils functionality when building
 * parent-child relationships is expected to be very rare; however if you 
 * do need this then instead of using this rule, create a CallMethodRule
 * specifying targetOffset of 1 in the constructor.</p>
 */

public class SetNextRule extends Rule {


    // ----------------------------------------------------------- Constructors


    
Construct a "set next" rule with the specified method name.  The
method's argument type is assumed to be the class of the
child object.

Params:
  • digester – The associated Digester
  • methodName – Method name of the parent method to call
Deprecated:The digester instance is now set in the Digester.addRule method. Use SetNextRule(String methodName) instead.
/**
     * Construct a "set next" rule with the specified method name.  The
     * method's argument type is assumed to be the class of the
     * child object.
     *
     * @param digester The associated Digester
     * @param methodName Method name of the parent method to call
     *
     * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
     * Use {@link #SetNextRule(String methodName)} instead.
     */
    @Deprecated
    public SetNextRule(Digester digester, String methodName) {

        this(methodName);

    }


    
Construct a "set next" rule with the specified method name.

Params:
  • digester – The associated Digester
  • methodName – Method name of the parent method to call
  • paramType – Java class of the parent method's argument
 (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 Digester.addRule method. Use SetNextRule(String methodName, String paramType) instead.
/**
     * Construct a "set next" rule with the specified method name.
     *
     * @param digester The associated Digester
     * @param methodName Method name of the parent method to call
     * @param paramType Java class of the parent method's argument
     *  (if you wish to use a primitive type, specify the corresonding
     *  Java wrapper class instead, such as <code>java.lang.Boolean</code>
     *  for a <code>boolean</code> parameter)
     *
     * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
     * Use {@link #SetNextRule(String methodName,String paramType)} instead.
     */
    @Deprecated
    public SetNextRule(Digester digester, String methodName,
                       String paramType) {

        this(methodName, paramType);

    }

    
Construct a "set next" rule with the specified method name.  The
method's argument type is assumed to be the class of the
child object.

Params:
  • methodName – Method name of the parent method to call
/**
     * Construct a "set next" rule with the specified method name.  The
     * method's argument type is assumed to be the class of the
     * child object.
     *
     * @param methodName Method name of the parent method to call
     */
    public SetNextRule(String methodName) {

        this(methodName, null);

    }


    
Construct a "set next" rule with the specified method name.

Params:
  • methodName – Method name of the parent method to call
  • paramType – Java class of the parent method's argument
 (if you wish to use a primitive type, specify the corresonding
 Java wrapper class instead, such as java.lang.Boolean
 for a boolean parameter)
/**
     * Construct a "set next" rule with the specified method name.
     *
     * @param methodName Method name of the parent method to call
     * @param paramType Java class of the parent method's argument
     *  (if you wish to use a primitive type, specify the corresonding
     *  Java wrapper class instead, such as <code>java.lang.Boolean</code>
     *  for a <code>boolean</code> parameter)
     */
    public SetNextRule(String methodName,
                       String paramType) {

        this.methodName = methodName;
        this.paramType = paramType;

    }


    // ----------------------------------------------------- Instance Variables


    
The method name to call on the parent object.

/**
     * The method name to call on the parent object.
     */
    protected String methodName = null;


    
The Java class name of the parameter type expected by the method.

/**
     * The Java class name of the parameter type expected by the method.
     */
    protected String paramType = null;

    
Should we use exact matching. Default is no.

/**
     * Should we use exact matching. Default is no.
     */
    protected boolean useExactMatch = false;

    // --------------------------------------------------------- Public Methods


    
Is exact matching being used.


This rule uses org.apache.commons.beanutils.MethodUtils 
to introspect the relevent objects so that the right method can be called.
Originally, MethodUtils.invokeExactMethod was used.
This matches methods very strictly 
and so may not find a matching method when one exists.
This is still the behaviour when exact matching is enabled.


When exact matching is disabled, MethodUtils.invokeMethod is used.
This method finds more methods but is less precise when there are several methods 
with correct signatures.
So, if you want to choose an exact signature you might need to enable this property.


The default setting is to disable exact matches.


Returns:true iff exact matching is enabled
Since:Digester Release 1.1.1
/**
     * <p>Is exact matching being used.</p>
     *
     * <p>This rule uses <code>org.apache.commons.beanutils.MethodUtils</code> 
     * to introspect the relevent objects so that the right method can be called.
     * Originally, <code>MethodUtils.invokeExactMethod</code> was used.
     * This matches methods very strictly 
     * and so may not find a matching method when one exists.
     * This is still the behaviour when exact matching is enabled.</p>
     *
     * <p>When exact matching is disabled, <code>MethodUtils.invokeMethod</code> is used.
     * This method finds more methods but is less precise when there are several methods 
     * with correct signatures.
     * So, if you want to choose an exact signature you might need to enable this property.</p>
     *
     * <p>The default setting is to disable exact matches.</p>
     *
     * @return true iff exact matching is enabled
     * @since Digester Release 1.1.1
     */
    public boolean isExactMatch() {
    
        return useExactMatch;
    }
    
    
Set whether exact matching is enabled.


See isExactMatch().


Params:
  • useExactMatch – should this rule use exact method matching
Since:Digester Release 1.1.1
/**
     * <p>Set whether exact matching is enabled.</p>
     *
     * <p>See {@link #isExactMatch()}.</p>
     *
     * @param useExactMatch should this rule use exact method matching
     * @since Digester Release 1.1.1
     */    
    public void setExactMatch(boolean useExactMatch) {

        this.useExactMatch = useExactMatch;
    }

    
Process the end of this element.

/**
     * Process the end of this element.
     */
    @Override
    public void end() throws Exception {

        // Identify the objects to be used
        Object child = digester.peek(0);
        Object parent = digester.peek(1);
        if (digester.log.isDebugEnabled()) {
            if (parent == null) {
                digester.log.debug("[SetNextRule]{" + digester.match +
                        "} Call [NULL PARENT]." +
                        methodName + "(" + child + ")");
            } else {
                digester.log.debug("[SetNextRule]{" + digester.match +
                        "} Call " + parent.getClass().getName() + "." +
                        methodName + "(" + child + ")");
            }
        }

        // Call the specified method
        Class<?> paramTypes[] = new Class<?>[1];
        if (paramType != null) {
            paramTypes[0] =
                    digester.getClassLoader().loadClass(paramType);
        } else {
            paramTypes[0] = child.getClass();
        }
        
        if (useExactMatch) {
        
            MethodUtils.invokeExactMethod(parent, methodName,
                new Object[]{ child }, paramTypes);
                
        } else {
        
            MethodUtils.invokeMethod(parent, methodName,
                new Object[]{ child }, paramTypes);
        
        }
    }


    
Render a printable version of this Rule.

/**
     * Render a printable version of this Rule.
     */
    @Override
    public String toString() {

        StringBuffer sb = new StringBuffer("SetNextRule[");
        sb.append("methodName=");
        sb.append(methodName);
        sb.append(", paramType=");
        sb.append(paramType);
        sb.append("]");
        return (sb.toString());

    }


}