naminghelper.java

用Java实现的23个常用设计模式源代码

//$Id: NamingHelper.java,v 1.6 2003/06/15 12:45:08 oneovthafew Exp $
package net.sf.hibernate.util;

import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Properties;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.Name;
import javax.naming.NameNotFoundException;
import javax.naming.NamingException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import net.sf.hibernate.cfg.Environment;

public final class NamingHelper {
	
	private static final Log log = LogFactory.getLog(NamingHelper.class);
	
	public static InitialContext getInitialContext(Properties props) throws NamingException {
		
		Hashtable hash = getJndiProperties(props);
		log.info("JNDI InitialContext properties:" + hash);
		try {
			return ( hash.size()==0 ) ?
			new InitialContext() :
			new InitialContext(hash);
		}
		catch (NamingException e) {
			log.error("Could not obtain initial context", e);
			throw e;
		}
	}
	
	/**
	 * Bind val to name in ctx, and make sure that all intermediate contexts exist.
	 *
	 * @param ctx the root context
	 * @param name the name as a string
	 * @param val the object to be bound
	 * @throws NamingException
	 */
	public static void bind(Context ctx, String name, Object val) throws NamingException {
		try {
			log.trace("binding: " + name);
			ctx.rebind(name, val);
		}
		catch (Exception e) {
			Name n = ctx.getNameParser(StringHelper.EMPTY_STRING).parse(name);
			while ( n.size() > 1 ) {
				String ctxName = n.get(0);
				
				Context subctx=null;
				try {
					log.trace("lookup: " + ctxName);
					subctx = (Context) ctx.lookup(ctxName);
				}
				catch (NameNotFoundException nfe) {}
				
				if (subctx!=null) {
					log.debug("Found subcontext: " + ctxName);
					ctx = subctx;
				}
				else {
					log.info("Creating subcontext: " + ctxName);
					ctx = ctx.createSubcontext(ctxName);
				}
				n = n.getSuffix(1);
			}
			log.trace("binding: " + n);
			ctx.rebind(n, val);
		}
		log.debug("Bound name: " + name);
	}
	
	/**
	 * Transform JNDI properties passed in the form <tt>hibernate.jndi.*</tt> to the
	 * format accepted by <tt>InitialContext</tt> by triming the leading "<tt>hibernate.jndi</tt>".
	 */
	public static Properties getJndiProperties(Properties properties) {
		
		HashSet specialProps = new HashSet();
		specialProps.add(Environment.JNDI_CLASS);
		specialProps.add(Environment.JNDI_URL);
		
		Iterator iter = properties.keySet().iterator();
		Properties result = new Properties();
		while ( iter.hasNext() ) {
			String prop = (String) iter.next();
			if ( prop.indexOf(Environment.JNDI_PREFIX) > -1 && !specialProps.contains(prop) ) {
				result.setProperty(
					prop.substring( Environment.JNDI_PREFIX.length()+1 ),
					properties.getProperty(prop)
				);
			}
		}
		
		String jndiClass = properties.getProperty(Environment.JNDI_CLASS);
		String jndiURL = properties.getProperty(Environment.JNDI_URL);
		// we want to be able to just use the defaults,
		// if JNDI environment properties are not supplied
		// so don't put null in anywhere
		if (jndiClass != null) result.put(Context.INITIAL_CONTEXT_FACTORY, jndiClass);
		if (jndiURL != null) result.put(Context.PROVIDER_URL, jndiURL);
		
		return result;
	}
	
	private NamingHelper() {}
	
}