proxydircontext.java

业界著名的tomcat服务器的最新6.0的源代码。

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.naming.resources;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Hashtable;

import javax.naming.Context;
import javax.naming.Name;
import javax.naming.NameNotFoundException;
import javax.naming.NameParser;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.directory.Attributes;
import javax.naming.directory.DirContext;
import javax.naming.directory.ModificationItem;
import javax.naming.directory.SearchControls;

import org.apache.naming.StringManager;

/**
 * Proxy Directory Context implementation.
 *
 * @author Remy Maucherat
 * @version $Revision: 467222 $ $Date: 2006-10-24 05:17:11 +0200 (mar., 24 oct. 2006) $
 */

public class ProxyDirContext implements DirContext {


    // -------------------------------------------------------------- Constants


    public static final String CONTEXT = "context";
    public static final String HOST = "host";


    // ----------------------------------------------------------- Constructors


    /**
     * Builds a proxy directory context using the given environment.
     */
    public ProxyDirContext(Hashtable env, DirContext dirContext) {
        this.env = env;
        this.dirContext = dirContext;
        if (dirContext instanceof BaseDirContext) {
            // Initialize parameters based on the associated dir context, like
            // the caching policy.
            BaseDirContext baseDirContext = (BaseDirContext) dirContext;
            if (baseDirContext.isCached()) {
                try {
                    cache = (ResourceCache) 
                        Class.forName(cacheClassName).newInstance();
                } catch (Exception e) {
                    //FIXME
                    e.printStackTrace();
                }
                cache.setCacheMaxSize(baseDirContext.getCacheMaxSize());
                cacheTTL = baseDirContext.getCacheTTL();
                cacheObjectMaxSize = baseDirContext.getCacheMaxSize() / 20;
            }
        }
        hostName = (String) env.get(HOST);
        contextName = (String) env.get(CONTEXT);
    }


    /**
     * Builds a clone of this proxy dir context, wrapping the given directory
     * context, and sharing the same cache.
     */
    // TODO: Refactor using the proxy field
    /*
    protected ProxyDirContext(ProxyDirContext proxyDirContext, 
                              DirContext dirContext, String vPath) {
        this.env = proxyDirContext.env;
        this.dirContext = dirContext;
        this.vPath = vPath;
        this.cache = proxyDirContext.cache;
        this.cacheMaxSize = proxyDirContext.cacheMaxSize;
        this.cacheSize = proxyDirContext.cacheSize;
        this.cacheTTL = proxyDirContext.cacheTTL;
        this.cacheObjectMaxSize = proxyDirContext.cacheObjectMaxSize;
        this.notFoundCache = proxyDirContext.notFoundCache;
        this.hostName = proxyDirContext.hostName;
        this.contextName = proxyDirContext.contextName;
    }
    */


    // ----------------------------------------------------- Instance Variables


    /**
     * Proxy DirContext (either this or the real proxy).
     */
    protected ProxyDirContext proxy = this;


    /**
     * Environment.
     */
    protected Hashtable env;


    /**
     * The string manager for this package.
     */
    protected StringManager sm = StringManager.getManager(Constants.Package);


    /**
     * Associated DirContext.
     */
    protected DirContext dirContext;


    /**
     * Virtual path.
     */
    protected String vPath = null;


    /**
     * Host name.
     */
    protected String hostName;


    /**
     * Context name.
     */
    protected String contextName;


    /**
     * Cache class.
     */
    protected String cacheClassName = 
        "org.apache.naming.resources.ResourceCache";


    /**
     * Cache.
     */
    protected ResourceCache cache = null;


    /**
     * Cache TTL.
     */
    protected int cacheTTL = 5000; // 5s


    /**
     * Max size of resources which will have their content cached.
     */
    protected int cacheObjectMaxSize = 512; // 512 KB


    /**
     * Immutable name not found exception.
     */
    protected NameNotFoundException notFoundException =
        new ImmutableNameNotFoundException();


    /**
     * Non cacheable resources.
     */
    protected String[] nonCacheable = { "/WEB-INF/lib/", "/WEB-INF/classes/" };


    // --------------------------------------------------------- Public Methods


    /**
     * Get the cache used for this context.
     */
    public ResourceCache getCache() {
        return cache;
    }


    /**
     * Return the actual directory context we are wrapping.
     */
    public DirContext getDirContext() {
        return this.dirContext;
    }


    /**
     * Return the document root for this component.
     */
    public String getDocBase() {
        if (dirContext instanceof BaseDirContext)
            return ((BaseDirContext) dirContext).getDocBase();
        else
            return "";
    }


    /**
     * Return the host name.
     */
    public String getHostName() {
        return this.hostName;
    }


    /**
     * Return the context name.
     */
    public String getContextName() {
        return this.contextName;
    }


    // -------------------------------------------------------- Context Methods


    /**
     * Retrieves the named object. If name is empty, returns a new instance 
     * of this context (which represents the same naming context as this 
     * context, but its environment may be modified independently and it may 
     * be accessed concurrently).
     * 
     * @param name the name of the object to look up
     * @return the object bound to name
     * @exception NamingException if a naming exception is encountered
     */
    public Object lookup(Name name)
        throws NamingException {
        CacheEntry entry = cacheLookup(name.toString());
        if (entry != null) {
            if (!entry.exists) {
                throw notFoundException;
            }
            if (entry.resource != null) {
                // Check content caching.
                return entry.resource;
            } else {
                return entry.context;
            }
        }
        Object object = dirContext.lookup(parseName(name));
        if (object instanceof InputStream)
            return new Resource((InputStream) object);
        else
            return object;
    }


    /**
     * Retrieves the named object.
     * 
     * @param name the name of the object to look up
     * @return the object bound to name
     * @exception NamingException if a naming exception is encountered
     */
    public Object lookup(String name)
        throws NamingException {
        CacheEntry entry = cacheLookup(name);
        if (entry != null) {
            if (!entry.exists) {
                throw notFoundException;
            }
            if (entry.resource != null) {
                return entry.resource;
            } else {
                return entry.context;
            }
        }
        Object object = dirContext.lookup(parseName(name));
        if (object instanceof InputStream) {
            return new Resource((InputStream) object);
        } else if (object instanceof DirContext) {
            return object;
        } else if (object instanceof Resource) {
            return object;
        } else {
            return new Resource(new ByteArrayInputStream
                (object.toString().getBytes()));
        }
    }


    /**
     * Binds a name to an object. All intermediate contexts and the target 
     * context (that named by all but terminal atomic component of the name) 
     * must already exist.
     * 
     * @param name the name to bind; may not be empty
     * @param obj the object to bind; possibly null
     * @exception NameAlreadyBoundException if name is already bound
     * @exception InvalidAttributesException if object did not supply all 
     * mandatory attributes
     * @exception NamingException if a naming exception is encountered
     */
    public void bind(Name name, Object obj)
        throws NamingException {
        dirContext.bind(parseName(name), obj);
        cacheUnload(name.toString());
    }