tilestool.java

一个用于java web页面开发的开源包

package org.apache.velocity.tools.struts;

/*
 * 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.Iterator;
import java.util.Map;
import java.util.Stack;

import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.tiles.AttributeDefinition;
import org.apache.struts.tiles.ComponentContext;
import org.apache.struts.tiles.ComponentDefinition;
import org.apache.struts.tiles.Controller;
import org.apache.struts.tiles.DefinitionAttribute;
import org.apache.struts.tiles.DefinitionNameAttribute;
import org.apache.struts.tiles.DefinitionsFactoryException;
import org.apache.struts.tiles.DirectStringAttribute;
import org.apache.struts.tiles.TilesUtil;
import org.apache.velocity.context.Context;
import org.apache.velocity.tools.view.ImportSupport;
import org.apache.velocity.tools.view.context.ViewContext;

/**
 * View tool to use struts-tiles with Velocity.
 * <p><pre>
 * Template example(s):
 *  &lt;!-- insert a tile --&gt;
 *  $tiles.myTileDefinition
 *
 *  &lt;!-- get named attribute value from the current tiles-context --&gt;
 *  $tiles.getAttribute("myTileAttribute")
 *
 *  &lt;!-- import all attributes of the current tiles-context into the velocity-context. --&gt;
 *  $tiles.importAttributes()
 *
 * Toolbox configuration:
 * &lt;tool&gt;
 *   &lt;key&gt;tiles&lt;/key&gt;
 *   &lt;scope&gt;request&lt;/scope&gt;
 *   &lt;class&gt;org.apache.velocity.tools.struts.TilesTool&lt;/class&gt;
 * &lt;/tool&gt;
 * </pre></p>
 *
 * <p>This tool should only be used in the request scope.</p>
 *
 * @author <a href="mailto:[e-mail]">Marino A. Jonsson</a>
 * @since VelocityTools 1.1
 * @version $Revision: 477914 $ $Date: 2006-11-21 13:52:11 -0800 (Tue, 21 Nov 2006) $
 */
public class TilesTool extends ImportSupport
{
    protected static final Log LOG = LogFactory.getLog(TilesTool.class);

    static final String PAGE_SCOPE = "page";
    static final String REQUEST_SCOPE = "request";
    static final String SESSION_SCOPE = "session";
    static final String APPLICATION_SCOPE = "application";

    protected Context velocityContext;

    /**
     * A stack to hold ComponentContexts while nested tile-definitions
     * are rendered.
     */
    protected Stack contextStack;

    /******************************* Constructors ****************************/

    /**
     * Default constructor. Tool must be initialized before use.
     */
    public TilesTool() {}

    /**
     * Initializes this tool.
     *
     * @param obj the current ViewContext
     * @throws IllegalArgumentException if the param is not a ViewContext
     */
    public void init(Object obj)
    {
        if (!(obj instanceof ViewContext))
        {
            throw new IllegalArgumentException("Tool can only be initialized with a ViewContext");
        }

        ViewContext viewContext = (ViewContext)obj;
        this.velocityContext = viewContext.getVelocityContext();
        this.request = viewContext.getRequest();
        this.response = viewContext.getResponse();
        this.application = viewContext.getServletContext();
    }

    /***************************** View Helpers ******************************/

    /**
     * A generic tiles insert function.
     *
     * <p>This is functionally equivalent to
     * <code>&lt;tiles:insert attribute="foo" /&gt;</code>.</p>
     *
     * @param obj Can be any of the following:
     *        AttributeDefinition,
     *        tile-definition name,
     *        tile-attribute name,
     *        regular uri.
     *        (checked in that order)
     * @return the rendered template or value as a String
     * @throws Exception on failure
     */
    public String get(Object obj)
    {
        try
        {
            Object value = getCurrentContext().getAttribute(obj.toString());
            if (value != null)
            {
                return processObjectValue(value);
            }
            return processAsDefinitionOrURL(obj.toString());
        }
        catch (Exception e)
        {
            LOG.error("Exeption while rendering Tile " + obj + ": ", e);
            return null;
        }
    }

    /**
     * Fetches a named attribute-value from the current tiles-context.
     *
     * <p>This is functionally equivalent to
     * <code>&lt;tiles:getAsString name="foo" /&gt;</code>.</p>
     *
     * @param name the name of the tiles-attribute to fetch
     * @return attribute value for the named attribute
     */
    public Object getAttribute(String name)
    {
        Object value = getCurrentContext().getAttribute(name);
        if (value == null)
        {
            LOG.warn("Tile attribute '" + name + "' wasn't found in context.");
        }
        return value;
    }

    /**
     * Imports the named attribute-value from the current tiles-context into the
     * current Velocity context.
     *
     * <p>This is functionally equivalent to
     * <code>&lt;tiles:importAttribute name="foo" /&gt;</code>
     *
     * @param name the name of the tiles-attribute to import
     */
    public void importAttribute(String name)
    {
        this.importAttribute(name, PAGE_SCOPE);
    }

    /**
     * Imports the named attribute-value from the current tiles-context into the
     * named context ("page", "request", "session", or "application").
     *
     * <p>This is functionally equivalent to
     * <code>&lt;tiles:importAttribute name="foo" scope="scopeValue" /&gt;</code>
     *
     * @param name the name of the tiles-attribute to import
     * @param scope the named context scope to put the attribute into.
     */
    public void importAttribute(String name, String scope)
    {
        Object value = getCurrentContext().getAttribute(name);
        if (value == null)
        {
            LOG.warn("Tile attribute '" + name + "' wasn't found in context.");
        }

        if (scope.equals(PAGE_SCOPE))
        {
            velocityContext.put(name, value);
        }
        else if (scope.equals(REQUEST_SCOPE))
        {
            request.setAttribute(name, value);
        }
        else if (scope.equals(SESSION_SCOPE))
        {
            request.getSession().setAttribute(name, value);
        }
        else if (scope.equals(APPLICATION_SCOPE))
        {
            application.setAttribute(name, value);
        }
    }

    /**
     * Imports all attributes in the current tiles-context into the
     * current velocity-context.
     *
     * <p>This is functionally equivalent to
     * <code>&lt;tiles:importAttribute /&gt;</code>.</p>
     */
    public void importAttributes()
    {
        this.importAttributes(PAGE_SCOPE);
    }

    /**
     * Imports all attributes in the current tiles-context into the named
     * context ("page", "request", "session", or "application").
     *
     * <p>This is functionally equivalent to
     * <code>&lt;tiles:importAttribute scope="scopeValue" /&gt;</code>.</p>
     *
     * @param scope the named context scope to put the attributes into.
     */
    public void importAttributes(String scope)
    {
        ComponentContext context = getCurrentContext();
        Iterator names = context.getAttributeNames();

        if (scope.equals(PAGE_SCOPE))
        {
            while (names.hasNext())
            {
                String name = (String)names.next();
                velocityContext.put(name, context.getAttribute(name));
            }
        }
        else if (scope.equals(REQUEST_SCOPE))
        {
            while (names.hasNext())
            {
                String name = (String)names.next();
                request.setAttribute(name, context.getAttribute(name));
            }
        }