abstractfunctionmap.java

一个工作流设计及定义的系统,可以直接与数据库结合进行系统工作流程的定义及应用.

/*
 * Copyright (c) 2005, John Mettraux, OpenWFE.org
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * 
 * . Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.  
 * 
 * . Redistributions in binary form must reproduce the above copyright notice, 
 *   this list of conditions and the following disclaimer in the documentation 
 *   and/or other materials provided with the distribution.
 * 
 * . Neither the name of the "OpenWFE" nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without
 *   specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * $Id: AbstractFunctionMap.java,v 1.8 2005/06/25 08:31:42 jmettraux Exp $
 */

//
// AbstractFunctionMap.java
//
// [e-mail]
//
// generated with 
// jtmpl 1.1.01 2004/05/19 ([e-mail])
//

package openwfe.org.engine.functions;

import java.lang.reflect.Method;

import openwfe.org.AbstractService;
import openwfe.org.ReflectionUtils;
import openwfe.org.ServiceException;
import openwfe.org.ApplicationContext;
import openwfe.org.engine.workitem.InFlowWorkItem;
import openwfe.org.engine.expressions.FlowExpression;


/**
 * The beginning of the implementation of a FunctionMap, it implements
 * the eval job, but not the parsing of the function map itself, may it
 * be XML or whatever.
 *
 * <p><font size=2>CVS Info :
 * <br>$Author: jmettraux $
 * <br>$Id: AbstractFunctionMap.java,v 1.8 2005/06/25 08:31:42 jmettraux Exp $ </font>
 *
 * @author [e-mail]
 */
public abstract class AbstractFunctionMap

    extends AbstractService

    implements FunctionMap

{

    private final static org.apache.log4j.Logger log = org.apache.log4j.Logger
        .getLogger(AbstractFunctionMap.class.getName());

    //
    // CONSTANTS & co

    private final static Class[] FUNCTION_ARG_TYPES =
        new Class[] 
        { 
            FlowExpression.class, 
            InFlowWorkItem.class, 
            String[].class 
        };

    //
    // FIELDS

    private java.util.List classes = null;
    private java.util.Map functionMap = null;

    //
    // CONSTRUCTORS

    /**
     * Builds this service (this is called by ApplicationContext upon
     * parsing a configuration file)
     */
    public void init 
        (final String serviceName, 
         final ApplicationContext context, 
         final java.util.Map serviceParams)
    throws 
        ServiceException
    {
        super.init(serviceName, context, serviceParams);

        buildMap();
    }

    //
    // METHODS from FunctionMap

    protected java.util.List getClasses () { return this.classes; }
    protected java.util.Map getFunctionMap () { return this.functionMap; }

    protected void setClasses (java.util.List l) { this.classes = l; }
    protected void setFunctionMap (java.util.Map m) { this.functionMap = m; }

    /*
     * Iterates through the classes registered in this map to find a given
     * function by its name.
     */
    private Class findClass (final String functionName)
    {
        final java.util.Iterator it = this.classes.iterator();
        while (it.hasNext())
        {
            final Class clazz = (Class)it.next();
            try
            {
                final Method m = clazz
                    .getMethod(functionName, FUNCTION_ARG_TYPES);
                return clazz;
            }
            catch (final Throwable t)
            {
                log.warn
                    ("findClass() did not find class for function named '"+
                     functionName+"' in class '"+clazz.getName()+"'");
                // continue;
            }
        }

        return null;
    }

    /**
     * This is the main method of a FunctionMap, given a functionName, a
     * workitem and an array of args.
     * Basic functions like "today()" do not care about args or the workitem.
     */
    public String eval 
        (final String functionName, 
         final FlowExpression fe,
         final InFlowWorkItem wi, 
         final String[] args)
    {
        Class clazz = (Class)this.functionMap.get(functionName);

        if (clazz == null)
        {
            clazz = findClass(functionName);

            if (clazz == null)
            {
                log.info
                    ("eval() did not find any class for function '"+
                     functionName+"'");
                return "";
            }

            log.debug("eval() class holding function is "+clazz.getName());

            this.functionMap.put(functionName, clazz);
                // cache
        }

        try
        {
            return (String)ReflectionUtils.invokeStatic
                (clazz,
                 functionName,
                 FUNCTION_ARG_TYPES,
                 new Object[] { fe, wi, args });
        }
        catch (Exception e)
        {
            log.warn("eval() failed", e);

            return e.toString();
        }
    }

    //
    // METHODS

    //
    // METHODS from Service

    //
    // ABSTRACT METHODS

    /**
     * This method has to be implemented in order to have a full featured
     * FunctionMap, it tells how to look for classes containing function
     * implementations.
     */
    protected abstract void buildMap () throws ServiceException;

    //
    // STATIC METHODS

}