Struts example source code file (Head.java)

This example Struts source code file (Head.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 - Struts tags/keywords

boolean, boolean, dojo, dojo, head, http, override, request, response, rfc3066, servlet, string, string, struts, strutstagattribute, strutstagattribute, strutstagskipinheritance, template

The Struts Head.java source code

/*
 * $Id: Head.java 651946 2008-04-27 13:41:38Z apetrelli $
 *
 * 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.struts2.dojo.components;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.views.annotations.StrutsTag;
import org.apache.struts2.views.annotations.StrutsTagAttribute;
import org.apache.struts2.views.annotations.StrutsTagSkipInheritance;

import com.opensymphony.xwork2.util.ValueStack;

/**
 * <!-- START SNIPPET: notice -->
 * The "head" tag renders required JavaScript code to configure Dojo and is required in order to use
 * any of the tags included in the Dojo plugin.</p>
 * <!-- END SNIPPET: notice -->
 * 
 * <!-- START SNIPPET: javadoc -->
 * <p>

 * 
 * <p>To debug javascript errors set the "debug" attribute to true, which will display Dojo 
 * (and Struts) warning and error messages at the bottom of the page. Core Dojo files are by default
 * compressed, to improve loading time, which makes them very hard to read. To debug Dojo and Struts
 * widgets, set the "compressed" attribute to true. Make sure to turn this option off before
 * moving your project into production, as uncompressed files will take longer to download.
 * </p>
 * <p>For troubleshooting javascript problems the following configuration is recommended:

 * <pre>
 *   <sx:head debug="true" cache="false" compressed="false" />
 * </pre>
 *
 * <p>Dojo files are loaded as required by the Dojo loading mechanism. The problem with this
 * approach is that the files are not cached by the browser, so reloading a page or navigating
 * to a different page that uses the same widgets will cause the files to be reloaded. To solve 
 * this problem a custom Dojo profile is distributed with the Dojo plugin. This profile contains
 * the files required by the tags in the Dojo plugin, all in one file (524Kb), which is cached 
 * by the browser. This file will take longer to load by the browser but it will be downloaded 
 * only once. By default the "cache" attribute is set to false.</p>
 * 
 * <p>Some tags like the "datetimepicker" can use different locales, to use a locale
 * that is different from the request locale, it must be specified on the "extraLocales" 
 * attribute. This attribute can contain a comma separated list of locale names. From
 * Dojo's documentation:</p>
 * 
 * <p>
 * The locale is a short string, defined by the host environment, which conforms to RFC 3066 
 * (http://www.ietf.org/rfc/rfc3066.txt) used in the HTML specification. 
 * It consists of short identifiers, typically two characters 
 * long which are case-insensitive. Note that Dojo uses dash separators, not underscores like 
 * Java (e.g. "en-us", not "en_US"). Typically country codes are used in the optional second 
 * identifier, and additional variants may be specified. For example, Japanese is "ja"; 
 * Japanese in Japan is "ja-jp". Notice that the lower case is intentional -- while Dojo 
 * will often convert all locales to lowercase to normalize them, it is the lowercase that 
 * must be used when defining your resources.
 * </p>
 * 
 * <p>The "locale" attribute configures Dojo's locale:

 * 
 * <p>"The locale Dojo uses on a page may be overridden by setting djConfig.locale. This may be 
 * done to accomodate applications with a known user profile or server pages which do manual
 * assembly and assume a certain locale. You may also set djConfig.extraLocale to load 
 * localizations in addition to your own, in case you want to specify a particular 
 * translation or have multiple languages appear on your page."</p>
 * 
 * <p>To improve loading time, the property "parseContent" is set to false by default. This property will
 * instruct Dojo to only build widgets using specific element ids. If the property is set to true
 * Dojo will scan the whole document looking for widgets.</p>
 * 
 * <p>Dojo 0.4.3 is distributed with the Dojo plugin, to use a different Dojo version, the 
 * "baseRelativePath" attribute can be set to the URL of the Dojo root folder on your application.
 * </p>
 * <!-- END SNIPPET: javadoc -->
 *
 * <p/> Examples
 *
 * <pre>
 * <!-- START SNIPPET: example1 -->
 * <%@ taglib prefix="sx" uri="/struts-dojo-tags" %>
 * <head>
 *   <title>My page</title>
 *   <sx:head/>
 * </head>
 * <!-- END SNIPPET: example1 -->
 * </pre>
 *
 * <pre>
 * <!-- START SNIPPET: example3 -->
 * <%@ taglib prefix="sx" uri="/struts-dojo-tags" %>
 * <head>
 *   <title>My page</title>
 *   <sx:head debug="true" extraLocales="en-us,nl-nl,de-de"/>
 * </head>
 * <!-- END SNIPPET: example3 -->
 * </pre>
 *
 */
@StrutsTag(name="head", tldBodyContent="empty", tldTagClass="org.apache.struts2.dojo.views.jsp.ui.HeadTag",
    description="Render a chunk of HEAD for your HTML file")
@StrutsTagSkipInheritance
public class Head extends org.apache.struts2.components.Head {
    public static final String TEMPLATE = "head";
    public static final String PARSE_CONTENT = "struts.dojo.head.parseContent";
    
    private String debug;
    private String compressed;
    private String baseRelativePath;
    private String extraLocales;
    private String locale;
    private String cache;
    private String parseContent;
    
    public Head(ValueStack stack, HttpServletRequest request, HttpServletResponse response) {
        super(stack, request, response);
    }

    protected String getDefaultTemplate() {
        return TEMPLATE;
    }

    public void evaluateParams() {
        super.evaluateParams();
        
        if (this.debug != null)
            addParameter("debug", findValue(this.debug, Boolean.class));
        if (this.compressed != null)
            addParameter("compressed", findValue(this.compressed, Boolean.class));
        if (this.baseRelativePath != null)
            addParameter("baseRelativePath", findString(this.baseRelativePath));
        if (this.extraLocales != null) {
            String locales = findString(this.extraLocales);
            addParameter("extraLocales", locales.split(","));
        }
        if (this.locale != null)
            addParameter("locale", findString(this.locale));
        if (this.cache != null)
            addParameter("cache", findValue(this.cache, Boolean.class));
        if (this.parseContent != null) {
            Boolean shouldParseContent = (Boolean) findValue(this.parseContent, Boolean.class);
            addParameter("parseContent", shouldParseContent);
            stack.getContext().put(PARSE_CONTENT, shouldParseContent);
        } else {
            addParameter("parseContent", false);
            stack.getContext().put(PARSE_CONTENT, false);
        }
    }

    @Override
    @StrutsTagSkipInheritance
    public void setTheme(String theme) {
        super.setTheme(theme);
    }
    
    @Override
    public String getTheme() {
        return "ajax";
    }
    
    public boolean isDebug() {
        return debug != null && Boolean.parseBoolean(debug);
    }

    @StrutsTagAttribute(description="Enable Dojo debug messages", defaultValue="false", type="Boolean")
    public void setDebug(String debug) {
        this.debug = debug;
    }

    @StrutsTagAttribute(description="Use compressed version of dojo.js", defaultValue="true", type="Boolean")
    public void setCompressed(String compressed) {
        this.compressed = compressed;
    }

    @StrutsTagAttribute(description="Context relative path of Dojo distribution folder", defaultValue="/struts/dojo")
    public void setBaseRelativePath(String baseRelativePath) {
        this.baseRelativePath = baseRelativePath;
    }

    @StrutsTagAttribute(description="Comma separated list of locale names to be loaded by Dojo, locale names must be specified as in RFC3066")
    public void setExtraLocales(String extraLocales) {
        this.extraLocales = extraLocales;
    }

    @StrutsTagAttribute(description="Default locale to be used by Dojo, locale name must be specified as in RFC3066")
    public void setLocale(String locale) {
        this.locale = locale;
    }

    @StrutsTagAttribute(description="Use Struts Dojo profile, which contains all Struts widgets in one file, making it possible to be chached by " +
                "the browser", defaultValue="true", type="Boolean")
    public void setCache(String cache) {
        this.cache = cache;
    }
    
    @StrutsTagAttribute(description="Parse the whole document for widgets", defaultValue="false", type="Boolean")
    public void setParseContent(String parseContent) {
        this.parseContent = parseContent;
    }
}