selectorcontext.java

业界著名的tomcat服务器的最新6.0的源代码。

     * <p>
     * This method is idempotent. It succeeds even if the terminal atomic 
     * name is not bound in the target context, but throws 
     * NameNotFoundException if any of the intermediate contexts do not exist. 
     * 
     * In a federated naming system, a context from one naming system may be 
     * bound to a name in another. One can subsequently look up and perform 
     * operations on the foreign context using a composite name. However, an 
     * attempt destroy the context using this composite name will fail with 
     * NotContextException, because the foreign context is not a "subcontext" 
     * of the context in which it is bound. Instead, use unbind() to remove 
     * the binding of the foreign context. Destroying the foreign context 
     * requires that the destroySubcontext() be performed on a context from 
     * the foreign context's "native" naming system.
     * 
     * @param name the name of the context to be destroyed; may not be empty
     * @exception NameNotFoundException if an intermediate context does not 
     * exist
     * @exception NotContextException if the name is bound but does not name 
     * a context, or does not name a context of the appropriate type
     */
    public void destroySubcontext(Name name)
        throws NamingException {
        getBoundContext().destroySubcontext(parseName(name));
    }


    /**
     * Destroys the named context and removes it from the namespace.
     * 
     * @param name the name of the context to be destroyed; may not be empty
     * @exception NameNotFoundException if an intermediate context does not 
     * exist
     * @exception NotContextException if the name is bound but does not name 
     * a context, or does not name a context of the appropriate type
     */
    public void destroySubcontext(String name)
        throws NamingException {
        getBoundContext().destroySubcontext(parseName(name));
    }


    /**
     * Creates and binds a new context. Creates a new context with the given 
     * name and binds it in the target context (that named by all but 
     * terminal atomic component of the name). All intermediate contexts and 
     * the target context must already exist.
     * 
     * @param name the name of the context to create; may not be empty
     * @return the newly created context
     * @exception NameAlreadyBoundException if name is already bound
     * @exception InvalidAttributesException if creation of the subcontext 
     * requires specification of mandatory attributes
     * @exception NamingException if a naming exception is encountered
     */
    public Context createSubcontext(Name name)
        throws NamingException {
        return getBoundContext().createSubcontext(parseName(name));
    }


    /**
     * Creates and binds a new context.
     * 
     * @param name the name of the context to create; may not be empty
     * @return the newly created context
     * @exception NameAlreadyBoundException if name is already bound
     * @exception InvalidAttributesException if creation of the subcontext 
     * requires specification of mandatory attributes
     * @exception NamingException if a naming exception is encountered
     */
    public Context createSubcontext(String name)
        throws NamingException {
        return getBoundContext().createSubcontext(parseName(name));
    }


    /**
     * Retrieves the named object, following links except for the terminal 
     * atomic component of the name. If the object bound to name is not a 
     * link, returns the object itself.
     * 
     * @param name the name of the object to look up
     * @return the object bound to name, not following the terminal link 
     * (if any).
     * @exception NamingException if a naming exception is encountered
     */
    public Object lookupLink(Name name)
        throws NamingException {
        return getBoundContext().lookupLink(parseName(name));
    }


    /**
     * Retrieves the named object, following links except for the terminal 
     * atomic component of the name.
     * 
     * @param name the name of the object to look up
     * @return the object bound to name, not following the terminal link 
     * (if any).
     * @exception NamingException if a naming exception is encountered
     */
    public Object lookupLink(String name)
        throws NamingException {
        return getBoundContext().lookupLink(parseName(name));
    }


    /**
     * Retrieves the parser associated with the named context. In a 
     * federation of namespaces, different naming systems will parse names 
     * differently. This method allows an application to get a parser for 
     * parsing names into their atomic components using the naming convention 
     * of a particular naming system. Within any single naming system, 
     * NameParser objects returned by this method must be equal (using the 
     * equals() test).
     * 
     * @param name the name of the context from which to get the parser
     * @return a name parser that can parse compound names into their atomic 
     * components
     * @exception NamingException if a naming exception is encountered
     */
    public NameParser getNameParser(Name name)
        throws NamingException {
        return getBoundContext().getNameParser(parseName(name));
    }


    /**
     * Retrieves the parser associated with the named context.
     * 
     * @param name the name of the context from which to get the parser
     * @return a name parser that can parse compound names into their atomic 
     * components
     * @exception NamingException if a naming exception is encountered
     */
    public NameParser getNameParser(String name)
        throws NamingException {
        return getBoundContext().getNameParser(parseName(name));
    }


    /**
     * Composes the name of this context with a name relative to this context.
     * <p>
     * Given a name (name) relative to this context, and the name (prefix) 
     * of this context relative to one of its ancestors, this method returns 
     * the composition of the two names using the syntax appropriate for the 
     * naming system(s) involved. That is, if name names an object relative 
     * to this context, the result is the name of the same object, but 
     * relative to the ancestor context. None of the names may be null.
     * 
     * @param name a name relative to this context
     * @param prefix the name of this context relative to one of its ancestors
     * @return the composition of prefix and name
     * @exception NamingException if a naming exception is encountered
     */
    public Name composeName(Name name, Name prefix)
        throws NamingException {
        prefix = (Name) prefix.clone();
        return prefix.addAll(name);
    }


    /**
     * Composes the name of this context with a name relative to this context.
     * 
     * @param name a name relative to this context
     * @param prefix the name of this context relative to one of its ancestors
     * @return the composition of prefix and name
     * @exception NamingException if a naming exception is encountered
     */
    public String composeName(String name, String prefix)
        throws NamingException {
        return prefix + "/" + name;
    }


    /**
     * Adds a new environment property to the environment of this context. If 
     * the property already exists, its value is overwritten.
     * 
     * @param propName the name of the environment property to add; may not 
     * be null
     * @param propVal the value of the property to add; may not be null
     * @exception NamingException if a naming exception is encountered
     */
    public Object addToEnvironment(String propName, Object propVal)
        throws NamingException {
        return getBoundContext().addToEnvironment(propName, propVal);
    }


    /**
     * Removes an environment property from the environment of this context. 
     * 
     * @param propName the name of the environment property to remove; 
     * may not be null
     * @exception NamingException if a naming exception is encountered
     */
    public Object removeFromEnvironment(String propName)
        throws NamingException {
        return getBoundContext().removeFromEnvironment(propName);
    }


    /**
     * Retrieves the environment in effect for this context. See class 
     * description for more details on environment properties. 
     * The caller should not make any changes to the object returned: their 
     * effect on the context is undefined. The environment of this context 
     * may be changed using addToEnvironment() and removeFromEnvironment().
     * 
     * @return the environment of this context; never null
     * @exception NamingException if a naming exception is encountered
     */
    public Hashtable getEnvironment()
        throws NamingException {
        return getBoundContext().getEnvironment();
    }


    /**
     * Closes this context. This method releases this context's resources 
     * immediately, instead of waiting for them to be released automatically 
     * by the garbage collector.
     * This method is idempotent: invoking it on a context that has already 
     * been closed has no effect. Invoking any other method on a closed 
     * context is not allowed, and results in undefined behaviour.
     * 
     * @exception NamingException if a naming exception is encountered
     */
    public void close()
        throws NamingException {
        getBoundContext().close();
    }


    /**
     * Retrieves the full name of this context within its own namespace.
     * <p>
     * Many naming services have a notion of a "full name" for objects in 
     * their respective namespaces. For example, an LDAP entry has a 
     * distinguished name, and a DNS record has a fully qualified name. This 
     * method allows the client application to retrieve this name. The string 
     * returned by this method is not a JNDI composite name and should not be 
     * passed directly to context methods. In naming systems for which the 
     * notion of full name does not make sense, 
     * OperationNotSupportedException is thrown.
     * 
     * @return this context's name in its own namespace; never null
     * @exception OperationNotSupportedException if the naming system does 
     * not have the notion of a full name
     * @exception NamingException if a naming exception is encountered
     */
    public String getNameInNamespace()
        throws NamingException {
        return prefix;
    }


    // ------------------------------------------------------ Protected Methods


    /**
     * Get the bound context.
     */
    protected Context getBoundContext()
        throws NamingException {

        if (initialContext) {
            String ICName = IC_PREFIX;
            if (ContextBindings.isThreadBound()) {
                ICName += ContextBindings.getThreadName();
            } else if (ContextBindings.isClassLoaderBound()) {
                ICName += ContextBindings.getClassLoaderName();
            }
            Context initialContext = ContextBindings.getContext(ICName);
            if (initialContext == null) {
                // Allocating a new context and binding it to the appropriate 
                // name
                initialContext = new NamingContext(env, ICName);
                ContextBindings.bindContext(ICName, initialContext);
            }
            return initialContext;
        } else {
            if (ContextBindings.isThreadBound()) {
                return ContextBindings.getThread();
            } else {
                return ContextBindings.getClassLoader();
            }
        }

    }


    /**
     * Strips the URL header.
     * 
     * @return the parsed name
     * @exception NamingException if there is no "java:" header or if no 
     * naming context has been bound to this thread
     */
    protected String parseName(String name) 
        throws NamingException {
        
        if ((!initialContext) && (name.startsWith(prefix))) {
            return (name.substring(prefixLength));
        } else {
            if (initialContext) {
                return (name);
            } else {
                throw new NamingException
                    (sm.getString("selectorContext.noJavaUrl"));
            }
        }
        
    }


    /**
     * Strips the URL header.
     * 
     * @return the parsed name
     * @exception NamingException if there is no "java:" header or if no 
     * naming context has been bound to this thread
     */
    protected Name parseName(Name name) 
        throws NamingException {

        if ((!initialContext) && (!name.isEmpty()) 
            && (name.get(0).equals(prefix))) {
            return (name.getSuffix(1));
        } else {
            if (initialContext) {
                return (name);
            } else {
                throw new NamingException
                    (sm.getString("selectorContext.noJavaUrl"));
            }
        }

    }


}