package org.apache.velocity.tools.view;
/*
* 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.
*/
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.ServletContext;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.context.Context;
import org.apache.velocity.tools.ToolContext;
import org.apache.velocity.tools.Toolbox;
/**
* <p>{@link ToolContext} implementation specific to the servlet environment.</p>
*
* <p>It provides the following special features:</p>
* <ul>
* <li>puts the request, response, session, and servlet context objects
* into the Velocity context for direct access, and keeps them
* read-only</li>
* <li>supports a read-only toolbox of view tools</li>
* <li>auto-searches servlet request attributes, session attributes and
* servlet context attribues for objects</li>
* </ul>
*
* <p>The {@link #get(String key)} method implements the following search order
* for objects:</p>
* <ol>
* <li>tool in a request scoped toolbox</li>
* <li>tool in a session scoped toolbox</li>
* <li>tool in a application scoped toolbox</li>
* <li>request, response, session, or servlet context</li>
* <li>object in the local map of objects (traditional use)</li>
* <li>request attributes, session attributes, servlet context attributes</li>
* </ol>
*
* <p>The purpose of this class is to make it easy for web designer to work
* with Java servlet based web applications. They do not need to be concerned
* with the concepts of request, session or application attributes and the
* lifetime of objects in these scopes.</p>
*
* <p>Note that the put() method always puts objects into the local map
* and does not allow tools or servlet classes to be overridden.
* </p>
*
* @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
* @author <a href="mailto:sidler@teamup.com">Gabe Sidler</a>
* @author Nathan Bubna
*
* @version $Id: ViewContext.java 514727 2007-03-05 16:49:03Z nbubna $
*/
public class ViewToolContext extends ToolContext implements ViewContext
{
private final HttpServletRequest request;
private final HttpServletResponse response;
private final ServletContext application;
private final VelocityEngine velocity;
private String toolboxKey = DEFAULT_TOOLBOX_KEY;
public ViewToolContext(VelocityEngine velocity,
HttpServletRequest request,
HttpServletResponse response,
ServletContext application)
{
super(velocity);
this.velocity = velocity;
this.request = request;
this.response = response;
this.application = application;
// automagically set common tool properties
putToolProperties();
}
protected void setToolboxKey(String key)
{
this.toolboxKey = key;
}
protected void putToolProperties()
{
putToolProperty(REQUEST, getRequest());
if (getRequest() != null)
{
putToolProperty(LOCALE_KEY, getRequest().getLocale());
}
putToolProperty(RESPONSE, getResponse());
putToolProperty(SESSION, getSession());
putToolProperty(SERVLET_CONTEXT_KEY, getServletContext());
putToolProperty(PATH_KEY, ServletUtils.getPath(getRequest()));
}
protected List<Toolbox> getToolboxes()
{
// this means once we find any toolbox,
// then we stop looking. adding boxes to
// the request/session/application attributes
// later will not work. once one is in, any
// later additions must be via addToolbox(Toolbox)
// or addToolboxesUnderKey(String toolboxKey)
if (super.getToolboxes().isEmpty())
{
addToolboxesUnderKey(this.toolboxKey);
}
return super.getToolboxes();
}
protected void addToolboxesUnderKey(String toolboxKey)
{
Toolbox reqTools = (Toolbox)getRequest().getAttribute(toolboxKey);
if (reqTools != null)
{
addToolbox(reqTools);
}
if (getSession() != null)
{
Toolbox sessTools = (Toolbox)getSession().getAttribute(toolboxKey);
if (sessTools != null)
{
addToolbox(sessTools);
}
}
Toolbox appTools = (Toolbox)getServletContext().getAttribute(toolboxKey);
if (appTools != null)
{
addToolbox(appTools);
}
}
/**
* <p>Looks up and returns the object with the specified key.</p>
* <p>See the class documentation for more details.</p>
*
* @param key the key of the object requested
* @return the requested object or null if not found
*/
public Object get(String key)
{
/* search for a tool first, keeping them read-only */
Object o = findTool(key);
if (o != null)
{
return o;
}
/* put servlet API access here to keep it read-only */
o = getServletApi(key);
if (o != null)
{
return o;
}
/* try the local context */
o = internalGet(key);
if (o != null)
{
return o;
}
/* if not found, wander down the scopes... */
return getAttribute(key);
}
/**
* Returns the current matching servlet request, response, session,
* or servlet context instance, or null if the key matches none of those
* keys.
*/
protected Object getServletApi(String key)
{
if (key.equals(REQUEST))
{
return request;
}
else if(key.equals(RESPONSE))
{
return response;
}
else if (key.equals(SESSION))
{
return getSession();
}
else if (key.equals(APPLICATION))
{
return application;
}
return null;
}
/**
* <p>Searches for the named attribute in request, session (if valid),
* and application scope(s) in order and returns the value associated
* or null.</p>
*
* @since VelocityTools 1.1
*/
public Object getAttribute(String key)
{
Object o = request.getAttribute(key);
if (o == null)
{
if (getSession() != null)
{
try
{
o = getSession().getAttribute(key);
}
catch (IllegalStateException ise)
{
// Handle invalidated session state
o = null;
}
}
if (o == null)
{
o = application.getAttribute(key);
}
}
return o;
}
/**
* <p>Returns the current servlet request.</p>
*/
public HttpServletRequest getRequest()
{
return request;
}
/**
* <p>Returns the current servlet response.</p>
*/
public HttpServletResponse getResponse()
{
return response;
}
/**
* <p>Returns the current session, if any.</p>
*/
public HttpSession getSession()
{
return getRequest().getSession(false);
}
/**
* <p>Returns the servlet context.</p>
*/
public ServletContext getServletContext()
{
return application;
}
/**
* <p>Returns a reference to the Velocity context (this object).</p>
*/
public Context getVelocityContext()
{
return this;
}
/**
* <p>Returns a reference to the VelocityEngine.</p>
*/
public VelocityEngine getVelocityEngine()
{
return velocity;
}
}