Struts example source code file (ConfigurationManager.java)

This example Struts source code file (ConfigurationManager.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 - Struts tags/keywords

arraylist, configuration, configurationmanager, configurationprovider, containerprovider, containerprovider, copyonwritearraylist, copyonwritearraylist, deprecated, deprecated, detected, list, list, reloading, threading, threads, util

The Struts ConfigurationManager.java source code

/*
 * Copyright 2002-2006,2009 The Apache Software Foundation.
 * 
 * Licensed 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 com.opensymphony.xwork2.config;

import com.opensymphony.xwork2.config.impl.DefaultConfiguration;
import com.opensymphony.xwork2.config.providers.XWorkConfigurationProvider;
import com.opensymphony.xwork2.config.providers.XmlConfigurationProvider;
import com.opensymphony.xwork2.util.FileManager;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;


/**
 * ConfigurationManager - central for XWork Configuration management, including
 * its ConfigurationProvider.
 *
 * @author Jason Carreira
 * @author tm_jee
 * @version $Date: 2011-02-02 22:13:23 +0100 (Wed, 02 Feb 2011) $ $Id: ConfigurationManager.java 1066628 2011-02-02 21:13:23Z jafl $
 */
public class ConfigurationManager {

    protected static final Logger LOG = LoggerFactory.getLogger(ConfigurationManager.class);
    protected Configuration configuration;
    protected Lock providerLock = new ReentrantLock();
    private List<ContainerProvider> containerProviders = new CopyOnWriteArrayList();
    private List<PackageProvider> packageProviders = new CopyOnWriteArrayList();
    protected String defaultFrameworkBeanName;

    public ConfigurationManager() {
        this("xwork");
    }
    
    public ConfigurationManager(String name) {
        this.defaultFrameworkBeanName = name;
    }

    /**
     * Get the current XWork configuration object.  By default an instance of DefaultConfiguration will be returned
     *
     * @see com.opensymphony.xwork2.config.impl.DefaultConfiguration
     */
    public synchronized Configuration getConfiguration() {
        if (configuration == null) {
            setConfiguration(createConfiguration(defaultFrameworkBeanName));
            try {
                configuration.reloadContainer(getContainerProviders());
            } catch (ConfigurationException e) {
                setConfiguration(null);
                throw new ConfigurationException("Unable to load configuration.", e);
            }
        } else {
            conditionalReload();
        }

        return configuration;
    }

    protected Configuration createConfiguration(String beanName) {
        return new DefaultConfiguration(beanName);
    }

    public synchronized void setConfiguration(Configuration configuration) {
        this.configuration = configuration;
    }
    
    /**
     * Get the current list of ConfigurationProviders. If no custom ConfigurationProviders have been added, this method
     * will return a list containing only the default ConfigurationProvider, XMLConfigurationProvider.  if a custom
     * ConfigurationProvider has been added, then the XmlConfigurationProvider must be added by hand.
     * </p>
     * <p/>
     * WARNING: This returns only ContainerProviders that can be cast into ConfigurationProviders
     *
     * @return the list of registered ConfigurationProvider objects
     * @see ConfigurationProvider
     * @deprecated Since 2.1, use {@link #getContainerProviders()}
     */
    @Deprecated public List<ConfigurationProvider> getConfigurationProviders() {
        List<ContainerProvider> contProviders = getContainerProviders();
        List<ConfigurationProvider> providers = new ArrayList();
        for (ContainerProvider prov : contProviders) {
            if (prov instanceof ConfigurationProvider) {
                providers.add((ConfigurationProvider) prov);
            }
        }
        return providers;
    }

    /**
     * Get the current list of ConfigurationProviders. If no custom ConfigurationProviders have been added, this method
     * will return a list containing only the default ConfigurationProvider, XMLConfigurationProvider.  if a custom
     * ConfigurationProvider has been added, then the XmlConfigurationProvider must be added by hand.
     * </p>
     * <p/>
     * TODO: the lazy instantiation of XmlConfigurationProvider should be refactored to be elsewhere.  the behavior described above seems unintuitive.
     *
     * @return the list of registered ConfigurationProvider objects
     * @see ConfigurationProvider
     */
    public List<ContainerProvider> getContainerProviders() {
        providerLock.lock();
        try {
            if (containerProviders.size() == 0) {
                containerProviders.add(new XWorkConfigurationProvider());
                containerProviders.add(new XmlConfigurationProvider("xwork.xml", false));
            }

            return containerProviders;
        } finally {
            providerLock.unlock();
        }
    }

    /**
     * Set the list of configuration providers
     *
     * @param configurationProviders
     * @deprecated Since 2.1, use {@link #setContainerProvider()}
     */
    @Deprecated public void setConfigurationProviders(List<ConfigurationProvider> configurationProviders) {
        // Silly copy necessary due to lack of ability to cast generic lists
        List<ContainerProvider> contProviders = new ArrayList();
        contProviders.addAll(configurationProviders);
        
        setContainerProviders(contProviders);
    }
        
    /**
     * Set the list of configuration providers
     *
     * @param containerProviders
     */
    public void setContainerProviders(List<ContainerProvider> containerProviders) {
        providerLock.lock();
        try {
            this.containerProviders = new CopyOnWriteArrayList<ContainerProvider>(containerProviders);
        } finally {
            providerLock.unlock();
        }
    }

    /**
     * adds a configuration provider to the List of ConfigurationProviders.  a given ConfigurationProvider may be added
     * more than once
     *
     * @param provider the ConfigurationProvider to register
     * @deprecated Since 2.1, use {@link #addContainerProvider()}
     */
    @Deprecated public void addConfigurationProvider(ConfigurationProvider provider) {
        addContainerProvider(provider);
    }
        
    /**
     * adds a configuration provider to the List of ConfigurationProviders.  a given ConfigurationProvider may be added
     * more than once
     *
     * @param provider the ConfigurationProvider to register
     */
    public void addContainerProvider(ContainerProvider provider) {
        if (!containerProviders.contains(provider)) {
            containerProviders.add(provider);
        }
    }
    
    /**
     * clears the registered ConfigurationProviders.  this method will call destroy() on each of the registered
     * ConfigurationProviders
     *
     * @see com.opensymphony.xwork2.config.ConfigurationProvider#destroy
     * @deprecated Since 2.1, use {@link #clearContainerProviders()}
     */
    @Deprecated public void clearConfigurationProviders() {
        clearContainerProviders();
    }
    
    public void clearContainerProviders() {
        for (ContainerProvider containerProvider : containerProviders) {
            try {
                containerProvider.destroy();
            }
            catch(Exception e) {
                LOG.warn("error while destroying container provider ["+containerProvider+"]", e);
            }
        }
        containerProviders.clear();
    }

    /**
     * Destroy its managing Configuration instance
     */
    public synchronized void destroyConfiguration() {
        clearConfigurationProviders(); // let's destroy the ConfigurationProvider first
        containerProviders = new CopyOnWriteArrayList<ContainerProvider>();
        if (configuration != null)
            configuration.destroy(); // let's destroy it first, before nulling it.
        configuration = null;
    }


    /**
     * Reloads the Configuration files if the configuration files indicate that they need to be reloaded.
     */
    public synchronized void conditionalReload() {
        if (FileManager.isReloadingConfigs()) {
            boolean reload;

            if (LOG.isDebugEnabled()) {
                LOG.debug("Checking ConfigurationProviders for reload.");
            }

            reload = false;

            List<ContainerProvider> providers = getContainerProviders();
            for (ContainerProvider provider : providers) {
                if (provider.needsReload()) {
                    if (LOG.isInfoEnabled()) {
                        LOG.info("Detected container provider "+provider+" needs to be reloaded.  Reloading all providers.");
                    }
                    reload = true;

                    //break;
                }
            }
            
            if (packageProviders != null && reload) {
                for (PackageProvider provider : packageProviders) {
                    if (provider.needsReload()) {
                        if (LOG.isInfoEnabled()) {
                            LOG.info("Detected package provider "+provider+" needs to be reloaded.  Reloading all providers.");
                        }
                        reload = true;
    
                        //break;
                    }
                }
            }

            if (reload) {
            	for (ContainerProvider containerProvider : containerProviders) {
                	try {
                		containerProvider.destroy();
                	}
                	catch(Exception e) {
                		LOG.warn("error while destroying configuration provider ["+containerProvider+"]", e);
                	}
                }
                packageProviders = configuration.reloadContainer(providers);
            }
        }
    }
    
    public synchronized void reload() {
        packageProviders = getConfiguration().reloadContainer(getContainerProviders());
    }
}