org.jharks.workflow.Rule Maven / Gradle / Ivy

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package org.jharks.workflow;

import java.util.List;


/**
 * The Rule class is an abstract class with a factory method that
 * allows for the instantiation of various rule implementations.  This 
 * ultimately allows for new Rule implementations to be written
 * and then plugged into the architecture by simply modifying the workflow 
 * XML configuration file.
 * 
 * @author Michael J. Rizzo
 * @version 1.0
 */

public abstract class Rule {
    
    /**
     * Check to see if rule applies according to provided input.
     * @param input the submitted input.
     * @return boolean indicating whether rule was applied or not.
     */
    public abstract boolean checkRule(Object input);
    
    /**
     * Abstract method to be implemented by all Rule 
     * implementations to allow for the retrieval of RuleCondition
     * instances that may be part of a Rule instance. 
     * @return the conditions of the Rule.
     */
    public abstract List getRuleConditions();
    
    /**
     * Add condition to conditions map. Performed at initialization time by digester.
     * @param rc the RuleCondition instance to be added to the rule conditions map.
     */
    public abstract void addRuleCondition(RuleCondition rc);
    
    /**
     * Factory method for creation of Rule implementations.
     * @param ruleImplName the class name of rule implementation to be 
     *        instantiated.
     * @return an instance of a Rule object.
     * @throws ClassNotFoundException if can not find classname specified.
     * @throws IllegalAccessException if the protection on object constructor
     *         is violated.
     * @throws InstantiationException if error occurs while instantiating
     *         the object.
     */
    public static Rule getRuleInstance(String ruleImplName) 
                                        throws ClassNotFoundException, 
                                               IllegalAccessException, 
                                               InstantiationException {
        
        return (Rule) Class.forName(ruleImplName).newInstance();     
    }
}