com.netspective.commons.report.tabular.calc.TabularReportCalcs.java Source code

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Here is the source code for com.netspective.commons.report.tabular.calc.TabularReportCalcs.java

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/*
 * Copyright (c) 2000-2004 Netspective Communications LLC. All rights reserved.
 *
 * Netspective Communications LLC ("Netspective") permits redistribution, modification and use of this file in source
 * and binary form ("The Software") under the Netspective Source License ("NSL" or "The License"). The following
 * conditions are provided as a summary of the NSL but the NSL remains the canonical license and must be accepted
 * before using The Software. Any use of The Software indicates agreement with the NSL.
 *
 * 1. Each copy or derived work of The Software must preserve the copyright notice and this notice unmodified.
 *
 * 2. Redistribution of The Software is allowed in object code form only (as Java .class files or a .jar file
 *    containing the .class files) and only as part of an application that uses The Software as part of its primary
 *    functionality. No distribution of the package is allowed as part of a software development kit, other library,
 *    or development tool without written consent of Netspective. Any modified form of The Software is bound by these
 *    same restrictions.
 *
 * 3. Redistributions of The Software in any form must include an unmodified copy of The License, normally in a plain
 *    ASCII text file unless otherwise agreed to, in writing, by Netspective.
 *
 * 4. The names "Netspective", "Axiom", "Commons", "Junxion", and "Sparx" are trademarks of Netspective and may not be
 *    used to endorse or appear in products derived from The Software without written consent of Netspective.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT,
 * ARE HEREBY DISCLAIMED.
 *
 * NETSPECTIVE AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE OR ANY THIRD PARTY AS A
 * RESULT OF USING OR DISTRIBUTING THE SOFTWARE. IN NO EVENT WILL NETSPECTIVE OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THE SOFTWARE, EVEN
 * IF IT HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 */
package com.netspective.commons.report.tabular.calc;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.apache.commons.discovery.tools.DiscoverClass;
import org.apache.commons.discovery.tools.DiscoverSingleton;
import org.apache.commons.lang.exception.NestableRuntimeException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class TabularReportCalcs {
    private static DiscoverClass discoverClass = new DiscoverClass();
    public static final String CALCMETHODNAME_GETIDENTIFIERS = "getIdentifiers";
    protected static final Log log = LogFactory.getLog(TabularReportCalcs.class);

    private static TabularReportCalcs instance = (TabularReportCalcs) DiscoverSingleton
            .find(TabularReportCalcs.class, TabularReportCalcs.class.getName());

    private Map calcsClassesMap = new HashMap();
    private Set calcsClassesSet = new HashSet();

    public static TabularReportCalcs getInstance() {
        return instance;
    }

    public void registerColumnDataCalc(Class cls) {
        Class actualClass = discoverClass.find(cls, cls.getName());
        String[] identifiers = getCalcIdentifiers(actualClass);
        for (int i = 0; i < identifiers.length; i++) {
            calcsClassesMap.put(identifiers[i], actualClass);
            if (log.isTraceEnabled())
                log.trace("Registered column data calculator " + actualClass.getName() + " as '" + identifiers[i]
                        + "'.");
        }
        calcsClassesSet.add(actualClass);
    }

    public String[] getCalcIdentifiers(Class vsClass) {
        Method getIdsMethod = null;
        try {
            getIdsMethod = vsClass.getMethod(CALCMETHODNAME_GETIDENTIFIERS, null);
        } catch (NoSuchMethodException e) {
            log.error("Error retrieving method " + CALCMETHODNAME_GETIDENTIFIERS, e);
            throw new NestableRuntimeException("Static method 'String[] " + CALCMETHODNAME_GETIDENTIFIERS
                    + "()' not found in column data calc " + vsClass.getName(), e);
        }

        try {
            return (String[]) getIdsMethod.invoke(null, null);
        } catch (Exception e) {
            log.error("Error executing method " + CALCMETHODNAME_GETIDENTIFIERS, e);
            throw new NestableRuntimeException("Exception while obtaining identifiers using 'String[] "
                    + CALCMETHODNAME_GETIDENTIFIERS + "()' method in column data calc " + vsClass.getName(), e);
        }
    }

    /**
     * Returns a freshly instantiated ColumnDataCalculator named "cmd". If "cmd" is an already-existing named
     * class it will return a newInstance() of that class. If the "cmd" is a class name, a newInstance() of that
     * particular class will be created and the class will be cached in the calcsClasses Map.
     */

    public ColumnDataCalculator createDataCalc(String id) {
        Class cls = (Class) calcsClassesMap.get(id);
        if (cls == null) {
            try {
                cls = Class.forName(id);
                registerColumnDataCalc(cls);
            } catch (ClassNotFoundException e) {
                return null;
            }
        }

        try {
            return (ColumnDataCalculator) cls.newInstance();
        } catch (Exception e) {
            throw new RuntimeException(e.toString());
        }
    }
}