applicationcontext.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.catalina.core;


import java.io.File;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

import javax.naming.Binding;
import javax.naming.NamingException;
import javax.naming.directory.DirContext;
import javax.servlet.RequestDispatcher;
import javax.servlet.Servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextAttributeEvent;
import javax.servlet.ServletContextAttributeListener;

import org.apache.catalina.Context;
import org.apache.catalina.Host;
import org.apache.catalina.Wrapper;
import org.apache.catalina.deploy.ApplicationParameter;
import org.apache.catalina.util.Enumerator;
import org.apache.catalina.util.ResourceSet;
import org.apache.catalina.util.ServerInfo;
import org.apache.catalina.util.StringManager;
import org.apache.naming.resources.DirContextURLStreamHandler;
import org.apache.naming.resources.Resource;
import org.apache.tomcat.util.buf.CharChunk;
import org.apache.tomcat.util.buf.MessageBytes;
import org.apache.tomcat.util.http.mapper.MappingData;


/**
 * Standard implementation of <code>ServletContext</code> that represents
 * a web application's execution environment.  An instance of this class is
 * associated with each instance of <code>StandardContext</code>.
 *
 * @author Craig R. McClanahan
 * @author Remy Maucherat
 * @version $Revision: 467222 $ $Date: 2006-10-24 05:17:11 +0200 (mar., 24 oct. 2006) $
 */

public class ApplicationContext
    implements ServletContext {

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


    /**
     * Construct a new instance of this class, associated with the specified
     * Context instance.
     *
     * @param context The associated Context instance
     */
    public ApplicationContext(String basePath, StandardContext context) {
        super();
        this.context = context;
        this.basePath = basePath;
    }


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


    /**
     * The context attributes for this context.
     */
    protected Map attributes = new ConcurrentHashMap();


    /**
     * List of read only attributes for this context.
     */
    private Map readOnlyAttributes = new ConcurrentHashMap();


    /**
     * The Context instance with which we are associated.
     */
    private StandardContext context = null;


    /**
     * Empty collection to serve as the basis for empty enumerations.
     * <strong>DO NOT ADD ANY ELEMENTS TO THIS COLLECTION!</strong>
     */
    private static final ArrayList empty = new ArrayList();


    /**
     * The facade around this object.
     */
    private ServletContext facade = new ApplicationContextFacade(this);


    /**
     * The merged context initialization parameters for this Context.
     */
    private Map parameters = null;


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


    /**
     * Base path.
     */
    private String basePath = null;


    /**
     * Thread local mapping data.
     */
    private ThreadLocal localMappingData = new ThreadLocal();


    /**
     * Thread local URI message bytes.
     */
    private ThreadLocal localUriMB = new ThreadLocal();


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


    /**
     * Return the resources object that is mapped to a specified path.
     * The path must begin with a "/" and is interpreted as relative to the
     * current context root.
     */
    public DirContext getResources() {

        return context.getResources();

    }


    // ------------------------------------------------- ServletContext Methods


    /**
     * Return the value of the specified context attribute, if any;
     * otherwise return <code>null</code>.
     *
     * @param name Name of the context attribute to return
     */
    public Object getAttribute(String name) {

        return (attributes.get(name));

    }


    /**
     * Return an enumeration of the names of the context attributes
     * associated with this context.
     */
    public Enumeration getAttributeNames() {

        return new Enumerator(attributes.keySet(), true);

    }


    /**
     * Return a <code>ServletContext</code> object that corresponds to a
     * specified URI on the server.  This method allows servlets to gain
     * access to the context for various parts of the server, and as needed
     * obtain <code>RequestDispatcher</code> objects or resources from the
     * context.  The given path must be absolute (beginning with a "/"),
     * and is interpreted based on our virtual host's document root.
     *
     * @param uri Absolute URI of a resource on the server
     */
    public ServletContext getContext(String uri) {

        // Validate the format of the specified argument
        if ((uri == null) || (!uri.startsWith("/")))
            return (null);

        Context child = null;
        try {
            Host host = (Host) context.getParent();
            String mapuri = uri;
            while (true) {
                child = (Context) host.findChild(mapuri);
                if (child != null)
                    break;
                int slash = mapuri.lastIndexOf('/');
                if (slash < 0)
                    break;
                mapuri = mapuri.substring(0, slash);
            }
        } catch (Throwable t) {
            return (null);
        }

        if (child == null)
            return (null);

        if (context.getCrossContext()) {
            // If crossContext is enabled, can always return the context
            return child.getServletContext();
        } else if (child == context) {
            // Can still return the current context
            return context.getServletContext();
        } else {
            // Nothing to return
            return (null);
        }
    }

    
    /**
     * Return the main path associated with this context.
     */
    public String getContextPath() {
        return context.getPath();
    }
    

    /**
     * Return the value of the specified initialization parameter, or
     * <code>null</code> if this parameter does not exist.
     *
     * @param name Name of the initialization parameter to retrieve
     */
    public String getInitParameter(final String name) {

        mergeParameters();
        return ((String) parameters.get(name));

    }


    /**
     * Return the names of the context's initialization parameters, or an
     * empty enumeration if the context has no initialization parameters.
     */
    public Enumeration getInitParameterNames() {

        mergeParameters();
        return (new Enumerator(parameters.keySet()));

    }


    /**
     * Return the major version of the Java Servlet API that we implement.
     */
    public int getMajorVersion() {

        return (Constants.MAJOR_VERSION);

    }


    /**
     * Return the minor version of the Java Servlet API that we implement.
     */
    public int getMinorVersion() {

        return (Constants.MINOR_VERSION);

    }


    /**
     * Return the MIME type of the specified file, or <code>null</code> if
     * the MIME type cannot be determined.
     *
     * @param file Filename for which to identify a MIME type
     */
    public String getMimeType(String file) {

        if (file == null)
            return (null);
        int period = file.lastIndexOf(".");
        if (period < 0)
            return (null);
        String extension = file.substring(period + 1);
        if (extension.length() < 1)
            return (null);
        return (context.findMimeMapping(extension));

    }


    /**
     * Return a <code>RequestDispatcher</code> object that acts as a
     * wrapper for the named servlet.
     *
     * @param name Name of the servlet for which a dispatcher is requested
     */
    public RequestDispatcher getNamedDispatcher(String name) {

        // Validate the name argument
        if (name == null)
            return (null);

        // Create and return a corresponding request dispatcher
        Wrapper wrapper = (Wrapper) context.findChild(name);
        if (wrapper == null)
            return (null);
        
        return new ApplicationDispatcher(wrapper, null, null, null, null, name);

    }


    /**
     * Return the real path for a given virtual path, if possible; otherwise
     * return <code>null</code>.
     *
     * @param path The path to the desired resource
     */
    public String getRealPath(String path) {

        if (!context.isFilesystemBased())
            return null;

        if (path == null) {
            return null;
        }

        File file = new File(basePath, path);
        return (file.getAbsolutePath());

    }


    /**
     * Return a <code>RequestDispatcher</code> instance that acts as a
     * wrapper for the resource at the given path.  The path must begin
     * with a "/" and is interpreted as relative to the current context root.
     *
     * @param path The path to the desired resource.
     */
    public RequestDispatcher getRequestDispatcher(String path) {

        // Validate the path argument
        if (path == null)
            return (null);
        if (!path.startsWith("/"))
            throw new IllegalArgumentException
                (sm.getString
                 ("applicationContext.requestDispatcher.iae", path));
        path = normalize(path);
        if (path == null)
            return (null);

        // Retrieve the thread local URI
        MessageBytes uriMB = (MessageBytes) localUriMB.get();
        if (uriMB == null) {
            uriMB = MessageBytes.newInstance();
            CharChunk uriCC = uriMB.getCharChunk();
            uriCC.setLimit(-1);
            localUriMB.set(uriMB);
        } else {
            uriMB.recycle();
        }

        // Get query string
        String queryString = null;
        int pos = path.indexOf('?');
        if (pos >= 0) {
            queryString = path.substring(pos + 1);
        } else {
            pos = path.length();
        }
 
        // Retrieve the thread local mapping data
        MappingData mappingData = (MappingData) localMappingData.get();
        if (mappingData == null) {
            mappingData = new MappingData();
            localMappingData.set(mappingData);
        }

        // Map the URI
        CharChunk uriCC = uriMB.getCharChunk();
        try {
            uriCC.append(context.getPath(), 0, context.getPath().length());
            /*
             * Ignore any trailing path params (separated by ';') for mapping
             * purposes
             */
            int semicolon = path.indexOf(';');
            if (pos >= 0 && semicolon > pos) {
                semicolon = -1;
            }
            uriCC.append(path, 0, semicolon > 0 ? semicolon : pos);
            context.getMapper().map(uriMB, mappingData);
            if (mappingData.wrapper == null) {
                return (null);
            }
            /*
             * Append any trailing path params (separated by ';') that were
             * ignored for mapping purposes, so that they're reflected in the
             * RequestDispatcher's requestURI
             */
            if (semicolon > 0) {
                uriCC.append(path, semicolon, pos - semicolon);
            }
        } catch (Exception e) {
            // Should never happen
            log(sm.getString("applicationContext.mapping.error"), e);
            return (null);
        }

        Wrapper wrapper = (Wrapper) mappingData.wrapper;
        String wrapperPath = mappingData.wrapperPath.toString();
        String pathInfo = mappingData.pathInfo.toString();

        mappingData.recycle();
        
        // Construct a RequestDispatcher to process this request
        return new ApplicationDispatcher
            (wrapper, uriCC.toString(), wrapperPath, pathInfo, 
             queryString, null);

    }



    /**
     * Return the URL to the resource that is mapped to a specified path.
     * The path must begin with a "/" and is interpreted as relative to the
     * current context root.
     *
     * @param path The path to the desired resource
     *
     * @exception MalformedURLException if the path is not given
     *  in the correct form
     */
    public URL getResource(String path)
        throws MalformedURLException {

        if (path == null || !path.startsWith("/")) {
            throw new MalformedURLException(sm.getString("applicationContext.requestDispatcher.iae", path));
        }
        
        path = normalize(path);
        if (path == null)
            return (null);

        String libPath = "/WEB-INF/lib/";
        if ((path.startsWith(libPath)) && (path.endsWith(".jar"))) {
            File jarFile = null;
            if (context.isFilesystemBased()) {
                jarFile = new File(basePath, path);
            } else {
                jarFile = new File(context.getWorkPath(), path);
            }