closeablebeanfactoryprovider.java

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package org.directwebremoting.guice.spring;

import com.google.inject.Provider;

import java.io.Closeable;
import java.io.IOException;

import org.directwebremoting.util.Logger;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.DisposableBean;


/**
 * Lazily creates a singleton BeanFactory and, when {@code close()} is 
 * called, destroys it if it exists and is a {@code DisposableBean}.
 */
class CloseableBeanFactoryProvider implements Closeable, Provider<BeanFactory> 
{    
    CloseableBeanFactoryProvider(BeanFactoryLoader loader)
    {
        this.loader = loader;
    }
    
    public synchronized BeanFactory get() {
        if (beanFactory == null)
        {
            beanFactory = loader.loadBeanFactory();
        }
        return beanFactory;
    }
    
    public synchronized void close() throws IOException 
    {
        if (beanFactory != null && beanFactory instanceof DisposableBean)
        {
            try 
            {
                ((DisposableBean) beanFactory).destroy();
                log.info("Destroyed BeanFactory from Guice provider.");
            } 
            catch (IOException e) 
            {
                log.info("Caught IO exception destroying BeanFactory: " + e);
                throw e;
            } 
            catch (Exception e) 
            {
                log.info("Unexpected exception while destroying BeanFactory: " + e);
                throw new RuntimeException(e);
            }
        }
    }
    
    private final BeanFactoryLoader loader;
    
    /* @GuardedBy("this") */ private BeanFactory beanFactory;

    /**
     * The log stream
     */
    private static final Logger log = Logger.getLogger(CloseableBeanFactoryProvider.class);
}