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Spring Framework example source code file (JndiObjectFactoryBean.java)

This example Spring Framework source code file (JndiObjectFactoryBean.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 - Spring Framework tags/keywords

class, class, classloader, factorybean, illegalargumentexception, illegalargumentexception, jndi, jndiobjectlocator, jndiobjecttargetsource, naming, namingexception, namingexception, object, object, proxyfactory

The Spring Framework JndiObjectFactoryBean.java source code

/*
 * Copyright 2002-2008 the original author or authors.
 *
 * 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 org.springframework.jndi;

import javax.naming.NamingException;

import org.springframework.aop.framework.ProxyFactory;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.util.ClassUtils;

/**
 * {@link org.springframework.beans.factory.FactoryBean} that looks up a
 * JNDI object. Exposes the object found in JNDI for bean references,
 * e.g. for data access object's "dataSource" property in case of a
 * {@link javax.sql.DataSource}.
 *
 * <p>The typical usage will be to register this as singleton factory
 * (e.g. for a certain JNDI-bound DataSource) in an application context,
 * and give bean references to application services that need it.
 *
 * <p>The default behavior is to look up the JNDI object on startup and cache it.
 * This can be customized through the "lookupOnStartup" and "cache" properties,
 * using a {@link JndiObjectTargetSource} underneath. Note that you need to specify
 * a "proxyInterface" in such a scenario, since the actual JNDI object type is not
 * known in advance.
 *
 * <p>Of course, bean classes in a Spring environment may lookup e.g. a DataSource
 * from JNDI themselves. This class simply enables central configuration of the
 * JNDI name, and easy switching to non-JNDI alternatives. The latter is
 * particularly convenient for test setups, reuse in standalone clients, etc.
 *
 * <p>Note that switching to e.g. DriverManagerDataSource is just a matter of
 * configuration: Simply replace the definition of this FactoryBean with a
 * {@link org.springframework.jdbc.datasource.DriverManagerDataSource} definition!
 *
 * @author Juergen Hoeller
 * @since 22.05.2003
 * @see #setProxyInterface
 * @see #setLookupOnStartup
 * @see #setCache
 * @see JndiObjectTargetSource
 */
public class JndiObjectFactoryBean extends JndiObjectLocator implements FactoryBean, BeanClassLoaderAware {

	private Class[] proxyInterfaces;

	private boolean lookupOnStartup = true;

	private boolean cache = true;

	private Object defaultObject;

	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

	private Object jndiObject;


	/**
	 * Specify the proxy interface to use for the JNDI object.
	 * <p>Typically used in conjunction with "lookupOnStartup"=false and/or "cache"=false.
	 * Needs to be specified because the actual JNDI object type is not known
	 * in advance in case of a lazy lookup.
	 * @see #setProxyInterfaces
	 * @see #setLookupOnStartup
	 * @see #setCache
	 */
	public void setProxyInterface(Class proxyInterface) {
		this.proxyInterfaces = new Class[] {proxyInterface};
	}

	/**
	 * Specify multiple proxy interfaces to use for the JNDI object.
	 * <p>Typically used in conjunction with "lookupOnStartup"=false and/or "cache"=false.
	 * Note that proxy interfaces will be autodetected from a specified "expectedType",
	 * if necessary.
	 * @see #setExpectedType
	 * @see #setLookupOnStartup
	 * @see #setCache
	 */
	public void setProxyInterfaces(Class[] proxyInterfaces) {
		this.proxyInterfaces = proxyInterfaces;
	}

	/**
	 * Set whether to look up the JNDI object on startup. Default is "true".
	 * <p>Can be turned off to allow for late availability of the JNDI object.
	 * In this case, the JNDI object will be fetched on first access.
	 * <p>For a lazy lookup, a proxy interface needs to be specified.
	 * @see #setProxyInterface
	 * @see #setCache
	 */
	public void setLookupOnStartup(boolean lookupOnStartup) {
		this.lookupOnStartup = lookupOnStartup;
	}

	/**
	 * Set whether to cache the JNDI object once it has been located.
	 * Default is "true".
	 * <p>Can be turned off to allow for hot redeployment of JNDI objects.
	 * In this case, the JNDI object will be fetched for each invocation.
	 * <p>For hot redeployment, a proxy interface needs to be specified.
	 * @see #setProxyInterface
	 * @see #setLookupOnStartup
	 */
	public void setCache(boolean cache) {
		this.cache = cache;
	}

	/**
	 * Specify a default object to fall back to if the JNDI lookup fails.
	 * Default is none.
	 * <p>This can be an arbitrary bean reference or literal value.
	 * It is typically used for literal values in scenarios where the JNDI environment
	 * might define specific config settings but those are not required to be present.
	 * <p>Note: This is only supported for lookup on startup.
	 * @see #setLookupOnStartup
	 */
	public void setDefaultObject(Object defaultObject) {
		this.defaultObject = defaultObject;
	}

	public void setBeanClassLoader(ClassLoader classLoader) {
		this.beanClassLoader = classLoader;
	}


	/**
	 * Look up the JNDI object and store it.
	 */
	public void afterPropertiesSet() throws IllegalArgumentException, NamingException {
		super.afterPropertiesSet();

		if (!this.lookupOnStartup || !this.cache) {
			// We need to create a proxy for this...
			if (this.proxyInterfaces == null) {
				Class expectedType = getExpectedType();
				if (expectedType != null) {
					this.proxyInterfaces = ClassUtils.getAllInterfacesForClass(expectedType, this.beanClassLoader);
				}
			}
			if (this.proxyInterfaces == null) {
				throw new IllegalArgumentException(
						"Cannot deactivate 'lookupOnStartup' or 'cache' without specifying a 'proxyInterface'");
			}
		}

		if (this.proxyInterfaces != null) {
			if (this.defaultObject != null) {
				throw new IllegalArgumentException(
						"'defaultObject' is not supported in combination with 'proxyInterface'");
			}
			// We need a proxy and a JndiObjectTargetSource.
			this.jndiObject = JndiObjectProxyFactory.createJndiObjectProxy(this);
		}

		else {
			if (this.defaultObject != null && getExpectedType() != null &&
					!getExpectedType().isInstance(this.defaultObject)) {
				throw new IllegalArgumentException("Default object [" + this.defaultObject +
						"] of type [" + this.defaultObject.getClass().getName() +
						"] is not of expected type [" + getExpectedType().getName() + "]");
			}
			// Locate specified JNDI object.
			this.jndiObject = lookupWithFallback();
		}
	}

	/**
	 * Lookup variant that that returns the specified "defaultObject"
	 * (if any) in case of lookup failure.
	 * @return the located object, or the "defaultObject" as fallback
	 * @throws NamingException in case of lookup failure without fallback
	 * @see #setDefaultObject
	 */
	protected Object lookupWithFallback() throws NamingException {
		ClassLoader originalClassLoader = ClassUtils.overrideThreadContextClassLoader(this.beanClassLoader);
		try {
			return lookup();
		}
		catch (TypeMismatchNamingException ex) {
			// Always let TypeMismatchNamingException through -
			// we don't want to fall back to the defaultObject in this case.
			throw ex;
		}
		catch (NamingException ex) {
			if (this.defaultObject != null) {
				if (logger.isDebugEnabled()) {
					logger.debug("JNDI lookup failed - returning specified default object instead", ex);
				}
				else if (logger.isInfoEnabled()) {
					logger.info("JNDI lookup failed - returning specified default object instead: " + ex);
				}
				return this.defaultObject;
			}
			throw ex;
		}
		finally {
			if (originalClassLoader != null) {
				Thread.currentThread().setContextClassLoader(originalClassLoader);
			}
		}
	}


	/**
	 * Return the singleton JNDI object.
	 */
	public Object getObject() {
		return this.jndiObject;
	}

	public Class getObjectType() {
		if (this.proxyInterfaces != null) {
			if (this.proxyInterfaces.length == 1) {
				return this.proxyInterfaces[0];
			}
			else if (this.proxyInterfaces.length > 1) {
				return createCompositeInterface(this.proxyInterfaces);
			}
		}
		if (this.jndiObject != null) {
			return this.jndiObject.getClass();
		}
		else {
			return getExpectedType();
		}
	}

	public boolean isSingleton() {
		return true;
	}


	/**
	 * Create a composite interface Class for the given interfaces,
	 * implementing the given interfaces in one single Class.
	 * <p>The default implementation builds a JDK proxy class for the
	 * given interfaces.
	 * @param interfaces the interfaces to merge
	 * @return the merged interface as Class
	 * @see java.lang.reflect.Proxy#getProxyClass
	 */
	protected Class createCompositeInterface(Class[] interfaces) {
		return ClassUtils.createCompositeInterface(interfaces, this.beanClassLoader);
	}


	/**
	 * Inner class to just introduce an AOP dependency when actually creating a proxy.
	 */
	private static class JndiObjectProxyFactory {

		private static Object createJndiObjectProxy(JndiObjectFactoryBean jof) throws NamingException {
			// Create a JndiObjectTargetSource that mirrors the JndiObjectFactoryBean's configuration.
			JndiObjectTargetSource targetSource = new JndiObjectTargetSource();
			targetSource.setJndiTemplate(jof.getJndiTemplate());
			targetSource.setJndiName(jof.getJndiName());
			targetSource.setExpectedType(jof.getExpectedType());
			targetSource.setResourceRef(jof.isResourceRef());
			targetSource.setLookupOnStartup(jof.lookupOnStartup);
			targetSource.setCache(jof.cache);
			targetSource.afterPropertiesSet();

			// Create a proxy with JndiObjectFactoryBean's proxy interface and the JndiObjectTargetSource.
			ProxyFactory proxyFactory = new ProxyFactory();
			proxyFactory.setInterfaces(jof.proxyInterfaces);
			proxyFactory.setTargetSource(targetSource);
			return proxyFactory.getProxy(jof.beanClassLoader);
		}
	}

}

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