Tomcat example source code file (ApplicationContextFacade.java)

This example Tomcat source code file (ApplicationContextFacade.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

class, enumeration, enumeration, hashmap, invocationtargetexception, net, network, object, object, privilegedactionexception, reflection, requestdispatcher, security, servlet, servletcontext, string, string, throwable, throwable, util

The Tomcat ApplicationContextFacade.java source code

/*
 * 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.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Set;

import javax.servlet.RequestDispatcher;
import javax.servlet.Servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;

import org.apache.catalina.Globals;
import org.apache.catalina.security.SecurityUtil;


/**
 * Facade object which masks the internal <code>ApplicationContext
 * object from the web application.
 *
 * @author Remy Maucherat
 * @author Jean-Francois Arcand
 * @version $Revision: 505593 $ $Date: 2007-02-10 01:54:56 +0100 (sam., 10 févr. 2007) $
 */

public final class ApplicationContextFacade
    implements ServletContext {
        
    // ---------------------------------------------------------- Attributes
    /**
     * Cache Class object used for reflection.
     */
    private HashMap classCache;
    
    
    /**
     * Cache method object.
     */
    private HashMap objectCache;
    
    
    // ----------------------------------------------------------- Constructors


    /**
     * Construct a new instance of this class, associated with the specified
     * Context instance.
     *
     * @param context The associated Context instance
     */
    public ApplicationContextFacade(ApplicationContext context) {
        super();
        this.context = context;
        
        classCache = new HashMap();
        objectCache = new HashMap();
        initClassCache();
    }
    
    
    private void initClassCache(){
        Class[] clazz = new Class[]{String.class};
        classCache.put("getContext", clazz);
        classCache.put("getMimeType", clazz);
        classCache.put("getResourcePaths", clazz);
        classCache.put("getResource", clazz);
        classCache.put("getResourceAsStream", clazz);
        classCache.put("getRequestDispatcher", clazz);
        classCache.put("getNamedDispatcher", clazz);
        classCache.put("getServlet", clazz);
        classCache.put("getInitParameter", clazz);
        classCache.put("setAttribute", new Class[]{String.class, Object.class});
        classCache.put("removeAttribute", clazz);
        classCache.put("getRealPath", clazz);
        classCache.put("getAttribute", clazz);
        classCache.put("log", clazz);
    }


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


    /**
     * Wrapped application context.
     */
    private ApplicationContext context = null;
    


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


    public ServletContext getContext(String uripath) {
        ServletContext theContext = null;
        if (SecurityUtil.isPackageProtectionEnabled()) {
            theContext = (ServletContext)
                doPrivileged("getContext", new Object[]{uripath});
        } else {
            theContext = context.getContext(uripath);
        }
        if ((theContext != null) &&
            (theContext instanceof ApplicationContext)){
            theContext = ((ApplicationContext)theContext).getFacade();
        }
        return (theContext);
    }


    public int getMajorVersion() {
        return context.getMajorVersion();
    }


    public int getMinorVersion() {
        return context.getMinorVersion();
    }


    public String getMimeType(String file) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (String)doPrivileged("getMimeType", new Object[]{file});
        } else {
            return context.getMimeType(file);
        }
    }


    public Set getResourcePaths(String path) {
        if (SecurityUtil.isPackageProtectionEnabled()){
            return (Set)doPrivileged("getResourcePaths", new Object[]{path});
        } else {
            return context.getResourcePaths(path);
        }
    }


    public URL getResource(String path)
        throws MalformedURLException {
        if (Globals.IS_SECURITY_ENABLED) {
            try {
                return (URL) invokeMethod(context, "getResource", 
                                          new Object[]{path});
            } catch(Throwable t) {
                if (t instanceof MalformedURLException){
                    throw (MalformedURLException)t;
                }
                return null;
            }
        } else {
            return context.getResource(path);
        }
    }


    public InputStream getResourceAsStream(String path) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (InputStream) doPrivileged("getResourceAsStream", 
                                              new Object[]{path});
        } else {
            return context.getResourceAsStream(path);
        }
    }


    public RequestDispatcher getRequestDispatcher(final String path) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (RequestDispatcher) doPrivileged("getRequestDispatcher", 
                                                    new Object[]{path});
        } else {
            return context.getRequestDispatcher(path);
        }
    }


    public RequestDispatcher getNamedDispatcher(String name) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (RequestDispatcher) doPrivileged("getNamedDispatcher", 
                                                    new Object[]{name});
        } else {
            return context.getNamedDispatcher(name);
        }
    }


    public Servlet getServlet(String name)
        throws ServletException {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            try {
                return (Servlet) invokeMethod(context, "getServlet", 
                                              new Object[]{name});
            } catch (Throwable t) {
                if (t instanceof ServletException) {
                    throw (ServletException) t;
                }
                return null;
            }
        } else {
            return context.getServlet(name);
        }
    }


    public Enumeration getServlets() {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (Enumeration) doPrivileged("getServlets", null);
        } else {
            return context.getServlets();
        }
    }


    public Enumeration getServletNames() {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (Enumeration) doPrivileged("getServletNames", null);
        } else {
            return context.getServletNames();
        }
   }


    public void log(String msg) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            doPrivileged("log", new Object[]{msg} );
        } else {
            context.log(msg);
        }
    }


    public void log(Exception exception, String msg) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            doPrivileged("log", new Class[]{Exception.class, String.class}, 
                         new Object[]{exception,msg});
        } else {
            context.log(exception, msg);
        }
    }


    public void log(String message, Throwable throwable) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            doPrivileged("log", new Class[]{String.class, Throwable.class}, 
                         new Object[]{message, throwable});
        } else {
            context.log(message, throwable);
        }
    }


    public String getRealPath(String path) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (String) doPrivileged("getRealPath", new Object[]{path});
        } else {
            return context.getRealPath(path);
        }
    }


    public String getServerInfo() {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (String) doPrivileged("getServerInfo", null);
        } else {
            return context.getServerInfo();
        }
    }


    public String getInitParameter(String name) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (String) doPrivileged("getInitParameter", 
                                         new Object[]{name});
        } else {
            return context.getInitParameter(name);
        }
    }


    public Enumeration getInitParameterNames() {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (Enumeration) doPrivileged("getInitParameterNames", null);
        } else {
            return context.getInitParameterNames();
        }
    }


    public Object getAttribute(String name) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return doPrivileged("getAttribute", new Object[]{name});
        } else {
            return context.getAttribute(name);
        }
     }


    public Enumeration getAttributeNames() {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (Enumeration) doPrivileged("getAttributeNames", null);
        } else {
            return context.getAttributeNames();
        }
    }


    public void setAttribute(String name, Object object) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            doPrivileged("setAttribute", new Object[]{name,object});
        } else {
            context.setAttribute(name, object);
        }
    }


    public void removeAttribute(String name) {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            doPrivileged("removeAttribute", new Object[]{name});
        } else {
            context.removeAttribute(name);
        }
    }


    public String getServletContextName() {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (String) doPrivileged("getServletContextName", null);
        } else {
            return context.getServletContextName();
        }
    }

       
    public String getContextPath() {
        if (SecurityUtil.isPackageProtectionEnabled()) {
            return (String) doPrivileged("getContextPath", null);
        } else {
            return context.getContextPath();
        }
    }

       
    /**
     * Use reflection to invoke the requested method. Cache the method object 
     * to speed up the process
     * @param appContext The AppliationContext object on which the method
     *                   will be invoked
     * @param methodName The method to call.
     * @param params The arguments passed to the called method.
     */
    private Object doPrivileged(ApplicationContext appContext,
                                final String methodName, 
                                final Object[] params) {
        try{
            return invokeMethod(appContext, methodName, params );
        } catch (Throwable t){
            throw new RuntimeException(t.getMessage());
        }

    }


    /**
     * Use reflection to invoke the requested method. Cache the method object 
     * to speed up the process
     *                   will be invoked
     * @param methodName The method to call.
     * @param params The arguments passed to the called method.
     */
    private Object doPrivileged(final String methodName, final Object[] params){
        try{
            return invokeMethod(context, methodName, params);
        }catch(Throwable t){
            throw new RuntimeException(t.getMessage());
        }
    }

    
    /**
     * Use reflection to invoke the requested method. Cache the method object 
     * to speed up the process
     * @param appContext The AppliationContext object on which the method
     *                   will be invoked
     * @param methodName The method to call.
     * @param params The arguments passed to the called method.
     */
    private Object invokeMethod(ApplicationContext appContext,
                                final String methodName, 
                                Object[] params) 
        throws Throwable{

        try{
            Method method = (Method)objectCache.get(methodName);
            if (method == null){
                method = appContext.getClass()
                    .getMethod(methodName, (Class[])classCache.get(methodName));
                objectCache.put(methodName, method);
            }
            
            return executeMethod(method,appContext,params);
        } catch (Exception ex){
            handleException(ex, methodName);
            return null;
        } finally {
            params = null;
        }
    }
    
    /**
     * Use reflection to invoke the requested method. Cache the method object 
     * to speed up the process
     * @param methodName The method to invoke.
     * @param clazz The class where the method is.
     * @param params The arguments passed to the called method.
     */    
    private Object doPrivileged(final String methodName, 
                                final Class[] clazz,
                                Object[] params){

        try{
            Method method = context.getClass()
                    .getMethod(methodName, (Class[])clazz);
            return executeMethod(method,context,params);
        } catch (Exception ex){
            try{
                handleException(ex, methodName);
            }catch (Throwable t){
                throw new RuntimeException(t.getMessage());
            }
            return null;
        } finally {
            params = null;
        }
    }
    
    
    /**
     * Executes the method of the specified <code>ApplicationContext
     * @param method The method object to be invoked.
     * @param context The AppliationContext object on which the method
     *                   will be invoked
     * @param params The arguments passed to the called method.
     */
    private Object executeMethod(final Method method, 
                                 final ApplicationContext context,
                                 final Object[] params) 
            throws PrivilegedActionException, 
                   IllegalAccessException,
                   InvocationTargetException {
                                     
        if (SecurityUtil.isPackageProtectionEnabled()){
           return AccessController.doPrivileged(new PrivilegedExceptionAction(){
                public Object run() throws IllegalAccessException, InvocationTargetException{
                    return method.invoke(context,  params);
                }
            });
        } else {
            return method.invoke(context, params);
        }        
    }

    
    /**
     *
     * Throw the real exception.
     * @param ex The current exception
     */
    private void handleException(Exception ex, String methodName)
	    throws Throwable {

        Throwable realException;
        
        if (ex instanceof PrivilegedActionException) {
            ex = ((PrivilegedActionException) ex).getException();
        }
        
        if (ex instanceof InvocationTargetException) {
            realException =
                ((InvocationTargetException) ex).getTargetException();
        } else {
            realException = ex;
        }   
        
        throw realException;
    }
}