Java tutorial
/* * Copyright 2002-2018 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 * * https://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 java.util.Hashtable; import java.util.Properties; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NameNotFoundException; import javax.naming.NamingException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.lang.Nullable; import org.springframework.util.CollectionUtils; /** * Helper class that simplifies JNDI operations. It provides methods to lookup and * bind objects, and allows implementations of the {@link JndiCallback} interface * to perform any operation they like with a JNDI naming context provided. * * @author Rod Johnson * @author Juergen Hoeller * @see JndiCallback * @see #execute */ public class JndiTemplate { protected final Log logger = LogFactory.getLog(getClass()); @Nullable private Properties environment; /** * Create a new JndiTemplate instance. */ public JndiTemplate() { } /** * Create a new JndiTemplate instance, using the given environment. */ public JndiTemplate(@Nullable Properties environment) { this.environment = environment; } /** * Set the environment for the JNDI InitialContext. */ public void setEnvironment(@Nullable Properties environment) { this.environment = environment; } /** * Return the environment for the JNDI InitialContext, if any. */ @Nullable public Properties getEnvironment() { return this.environment; } /** * Execute the given JNDI context callback implementation. * @param contextCallback the JndiCallback implementation to use * @return a result object returned by the callback, or {@code null} * @throws NamingException thrown by the callback implementation * @see #createInitialContext */ @Nullable public <T> T execute(JndiCallback<T> contextCallback) throws NamingException { Context ctx = getContext(); try { return contextCallback.doInContext(ctx); } finally { releaseContext(ctx); } } /** * Obtain a JNDI context corresponding to this template's configuration. * Called by {@link #execute}; may also be called directly. * <p>The default implementation delegates to {@link #createInitialContext()}. * @return the JNDI context (never {@code null}) * @throws NamingException if context retrieval failed * @see #releaseContext */ public Context getContext() throws NamingException { return createInitialContext(); } /** * Release a JNDI context as obtained from {@link #getContext()}. * @param ctx the JNDI context to release (may be {@code null}) * @see #getContext */ public void releaseContext(@Nullable Context ctx) { if (ctx != null) { try { ctx.close(); } catch (NamingException ex) { logger.debug("Could not close JNDI InitialContext", ex); } } } /** * Create a new JNDI initial context. Invoked by {@link #getContext}. * <p>The default implementation use this template's environment settings. * Can be subclassed for custom contexts, e.g. for testing. * @return the initial Context instance * @throws NamingException in case of initialization errors */ protected Context createInitialContext() throws NamingException { Hashtable<?, ?> icEnv = null; Properties env = getEnvironment(); if (env != null) { icEnv = new Hashtable<>(env.size()); CollectionUtils.mergePropertiesIntoMap(env, icEnv); } return new InitialContext(icEnv); } /** * Look up the object with the given name in the current JNDI context. * @param name the JNDI name of the object * @return object found (cannot be {@code null}; if a not so well-behaved * JNDI implementations returns null, a NamingException gets thrown) * @throws NamingException if there is no object with the given * name bound to JNDI */ public Object lookup(final String name) throws NamingException { if (logger.isDebugEnabled()) { logger.debug("Looking up JNDI object with name [" + name + "]"); } Object result = execute(ctx -> ctx.lookup(name)); if (result == null) { throw new NameNotFoundException( "JNDI object with [" + name + "] not found: JNDI implementation returned null"); } return result; } /** * Look up the object with the given name in the current JNDI context. * @param name the JNDI name of the object * @param requiredType type the JNDI object must match. Can be an interface or * superclass of the actual class, or {@code null} for any match. For example, * if the value is {@code Object.class}, this method will succeed whatever * the class of the returned instance. * @return object found (cannot be {@code null}; if a not so well-behaved * JNDI implementations returns null, a NamingException gets thrown) * @throws NamingException if there is no object with the given * name bound to JNDI */ @SuppressWarnings("unchecked") public <T> T lookup(String name, @Nullable Class<T> requiredType) throws NamingException { Object jndiObject = lookup(name); if (requiredType != null && !requiredType.isInstance(jndiObject)) { throw new TypeMismatchNamingException(name, requiredType, jndiObject.getClass()); } return (T) jndiObject; } /** * Bind the given object to the current JNDI context, using the given name. * @param name the JNDI name of the object * @param object the object to bind * @throws NamingException thrown by JNDI, mostly name already bound */ public void bind(final String name, final Object object) throws NamingException { if (logger.isDebugEnabled()) { logger.debug("Binding JNDI object with name [" + name + "]"); } execute(ctx -> { ctx.bind(name, object); return null; }); } /** * Rebind the given object to the current JNDI context, using the given name. * Overwrites any existing binding. * @param name the JNDI name of the object * @param object the object to rebind * @throws NamingException thrown by JNDI */ public void rebind(final String name, final Object object) throws NamingException { if (logger.isDebugEnabled()) { logger.debug("Rebinding JNDI object with name [" + name + "]"); } execute(ctx -> { ctx.rebind(name, object); return null; }); } /** * Remove the binding for the given name from the current JNDI context. * @param name the JNDI name of the object * @throws NamingException thrown by JNDI, mostly name not found */ public void unbind(final String name) throws NamingException { if (logger.isDebugEnabled()) { logger.debug("Unbinding JNDI object with name [" + name + "]"); } execute(ctx -> { ctx.unbind(name); return null; }); } }