Commons Digester example source code file (SetTopRule.java)

This example Commons Digester source code file (SetTopRule.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Digester tags/keywords

call, child, class, deprecated, deprecated, object, object, override, rule, settoprule, settoprule, string, string, stringbuffer

The Commons Digester SetTopRule.java source code

/* $Id: SetTopRule.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;


/**
 * <p>Rule implementation that calls a "set parent" method on the top (child)
 * object, passing the (top-1) (parent) object as an argument.</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>
 */

public class SetTopRule extends Rule {


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


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

        this(methodName);

    }


    /**
     * Construct a "set parent" rule with the specified method name.
     *
     * @param digester The associated Digester
     * @param methodName Method name of the "set parent" method to call
     * @param paramType Java class of the "set 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
     *  for a <code>boolean parameter)
     *
     * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
     * Use {@link #SetTopRule(String methodName, String paramType)} instead.
     */
    @Deprecated
    public SetTopRule(Digester digester, String methodName,
                      String paramType) {

        this(methodName, paramType);

    }

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

        this(methodName, null);

    }


    /**
     * Construct a "set parent" rule with the specified method name.
     *
     * @param methodName Method name of the "set parent" method to call
     * @param paramType Java class of the "set 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
     *  for a <code>boolean parameter)
     */
    public SetTopRule(String methodName,
                      String paramType) {

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

    }


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


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


    /**
     * The Java class name of the parameter type expected by the method.
     */
    protected String paramType = null;
    
    /**
     * Should we use exact matching. Default is no.
     */
    protected boolean useExactMatch = false;


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

    /**
     * <p>Is exact matching being used.

     *
     * <p>This rule uses org.apache.commons.beanutils.MethodUtils 
     * to introspect the relevent objects so that the right method can be called.
     * Originally, <code>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.</p>
     *
     * <p>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.</p>
     *
     * <p>The default setting is to disable exact matches.

     *
     * @return true iff exact matching is enabled
     * @since Digester Release 1.1.1
     */
    public boolean isExactMatch() {
    
        return useExactMatch;
    }
    
    /**
     * <p>Set whether exact matching is enabled.

     *
     * <p>See {@link #isExactMatch()}.

     *
     * @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.
     */
    @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 (child == null) {
                digester.log.debug("[SetTopRule]{" + digester.match +
                        "} Call [NULL CHILD]." +
                        methodName + "(" + parent + ")");
            } else {
                digester.log.debug("[SetTopRule]{" + digester.match +
                        "} Call " + child.getClass().getName() + "." +
                        methodName + "(" + parent + ")");
            }
        }

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

        if (useExactMatch) {
        
            MethodUtils.invokeExactMethod(child, methodName,
                new Object[]{ parent }, paramTypes);
                
        } else {
        
            MethodUtils.invokeMethod(child, methodName,
                new Object[]{ parent }, paramTypes);
        
        }
    }


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

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

    }


}