/*
* 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.
*
* $Header:$
*/
package org.apache.beehive.netui.tags.template;
import javax.servlet.ServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
import java.io.IOException;
import java.io.Writer;
import java.util.HashMap;
/**
* The Attribute tag defines an attribute within a template that may be set
* from a content page. For example, the page's title may be defined as an
* attribute in the template and then provided by each content page using the
* template. The attribute has a name and default value. If the content
* page specifies a value for the attribute it will be used, otherwise
* the default value is used.
* @jsptagref.tagdescription
*
* Defines a property placeholder within a template. The
* value of these placeholders may be set
* from a content page.
*
* <p>For example, a title placeholder may be defined
* in the template.
*
* <p><b>In the template JSP page...</b>
*
* <pre> <head>
* <title>
* <netui-template:attribute name="title"/>
* </title>
* </head></pre>
*
* <p>Then content pages may set the value of this placeholder using the
* {@link SetAttribute} tag.
*
* <p><b>In a content JSP page...</b>
*
* <pre> <netui-template:setAttribute name="title" value="myContentPage1.jsp"/></pre>
*
* <p>The HTML rendered in the browser appears as follows.
*
* <p><b>Rendered HTML in the browser...</b>
*
* <pre> <head>
* <title>
* myContentPage1.jsp
* </title>
* </head></pre>
*
* If the <netui-template:setAttribute> tag specifies no value to be set in the
* placeholder, then the
* {@link Attribute} tag's <code>defaultValue</code> will be used.
*
* <pre> <netui-template:attribute name="title" <b>defaultValue="My Page"</b>/></pre>
*
* The <netui-template:attribute> tag may also be used to define placeholders within
* JSP and HTML tags.
*
* <p><b>In the template JSP page...</b>
*
* <pre> <td colspan="3" bgcolor="<b><netui-template:attribute name="headerColor" defaultValue="#ffffff"/></b>"></pre>
*
* @example
* <p>In this sample, a <netui-template:attribute> tag defines a value placeholder
* within a <td> tag</p>
*
* <pre> <td colspan="3" bgcolor="<b><netui-template:attribute name="headerColor" defaultValue="#ffffff"/></b>"></pre>
*
* <p>Now a content JSP page can control the background color of the <td>.
*
* <pre> <netui-template:setAttribute name="headerColor" value="lightgreen"/></pre>
*
* The HTML rendered in the browser will appear as follows.
*
* <pre> <td colspan="3" bgcolor="lightgreen"></pre>
*
* @netui:tag name="attribute" description="Place this tag in a template file, and then set its value with the netui-template:setAttribute tag."
*/
public class
Attribute extends TagSupport
implements TemplateConstants
{
/**
* The name of the attribute.
*/
private String _name;
/**
* Default value
*/
private String _defaultValue;
/**
* Sets the <code>name</code> for the <code>Attribute</code>. An
* attribute may be used more than once in a template page.
* @param name The name of the attribute. The name does
* not need to be unique because it may be used more than once
* on the page.
*
* @jsptagref.attributedescription
* The <code>name</code> for the <netui-template:attribute> placeholder. The <code>name</code>
* may be used more than once in a template page.
*
* @jsptagref.databindable false
*
* @jsptagref.attributesyntaxvalue <i>string_name</i>
*
* @netui:attribute required="true" rtexprvalue="true"
* description="The name for the <netui-template:attribute> placeholder. The name
* may be used more than once in a template page."
*/
public void setName(String name) {
_name = name;
}
/**
* Sets the <code>defaultValue</code> for the <code>Attribute</code>.
* If the content page does not define a value for this attribute
* through the <code>SetAttribute</code> tag, then the
* <code>defaultValue</code> will be used.
* If neither a value nor <code>defaultValue</code> is set, then the
* empty String "" will be output.
* @param defaultValue The value to set the defaultValue property.
*
* @jsptagref.attributedescription
* The default value for <netui-template:attribute> placeholder.
* If a content page does not define a value for the placeholder
* through its <netui-template:setAttribute> tag, then the
* <code>defaultValue</code> will be used.
* If neither a value nor <code>defaultValue</code> is set, then the
* empty String "" will be output.
*
* @jsptagref.databindable false
*
* @jsptagref.attributesyntaxvalue <i>string_defaultValue</i>
*
* @netui:attribute required="false" rtexprvalue="true"
* description="The default value for <netui-template:attribute> placeholder."
*/
public void setDefaultValue(String defaultValue) {
_defaultValue = defaultValue;
}
/**
* Renders the content of the attribute.
* @return EVAL_PAGE to continue evaluation of the page.
* @throws JspException If there is any failure in the tag.
*/
public int doStartTag()
throws JspException {
ServletRequest req = pageContext.getRequest();
HashMap atts = (HashMap) req.getAttribute(TEMPLATE_ATTRIBUTES);
try {
if (atts != null) {
String val = (String) atts.get(_name);
if (val != null) {
Writer out = pageContext.getOut();
out.write(val);
}
else {
Writer out = pageContext.getOut();
if (_defaultValue != null)
out.write(_defaultValue);
else
out.write("");
}
}
else {
Writer out = pageContext.getOut();
if (_defaultValue != null)
out.write(_defaultValue);
else
out.write("");
}
}
catch (IOException e) {
localRelease();
JspException jspException = new JspException("Caught IO Exception:" + e.getMessage(),e);
// todo: future cleanup
// The 2.5 Servlet api will set the initCause in the Throwable superclass during construction,
// this will cause an IllegalStateException on the following call.
if (jspException.getCause() == null) {
jspException.initCause(e);
}
throw jspException;
}
localRelease();
return EVAL_PAGE;
}
/**
* Resets all of the fields of the tag.
*/
// this is the root because this tag doesn't extend AbstractBaseTag
protected void localRelease() {
_name = null;
_defaultValue = null;
}
}