org.springframework.web.servlet.tags.TransformTag Maven / Gradle / Ivy
/*
* Copyright 2002-2005 the original author or authors.
*
* Licensed 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.springframework.web.servlet.tags;
import java.beans.PropertyEditor;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
import org.springframework.web.util.ExpressionEvaluationUtils;
import org.springframework.web.util.HtmlUtils;
import org.springframework.web.util.TagUtils;
/**
* Tag for transforming reference data values from form controllers and
* other objects inside a spring:bind tag.
*
* The BindTag has a PropertyEditor that it uses to transform properties of
* a bean to a String, useable in HTML forms. This tag uses that PropertyEditor
* to transform objects passed into this tag.
*
* @author Alef Arendsen
* @author Juergen Hoeller
* @since 20.09.2003
* @see BindTag
*/
public class TransformTag extends HtmlEscapingAwareTag {
/** the value to transform using the appropriate property editor */
private Object value;
/** the variable to put the result in */
private String var;
/** the scope of the variable the result will be put in */
private String scope = TagUtils.SCOPE_PAGE;
/**
* Set the value to transform, using the appropriate PropertyEditor
* from the enclosing BindTag.
*
The value can either be a plain value to transform (a hard-coded String
* value in a JSP or a JSP expression), or a JSP EL expression to be evaluated
* (transforming the result of the expression).
*
Like all of Spring's JSP tags, this tag is capable of parsing EL expressions
* itself, on any JSP version. Note, however, that EL expressions in a JSP 2.0 page
* will be evaluated by the JSP container, with the result getting passed in here.
* For this reason, the type of this property is Object (accepting any result
* object from a pre-evaluated expression) rather than String.
*/
public void setValue(Object value) {
this.value = value;
}
/**
* Set PageContext attribute name under which to expose
* a variable that contains the result of the transformation.
* @see #setScope
* @see javax.servlet.jsp.PageContext#setAttribute
*/
public void setVar(String var) {
this.var = var;
}
/**
* Set the scope to export the variable to.
* Default is SCOPE_PAGE ("page").
* @see #setVar
* @see org.springframework.web.util.TagUtils#SCOPE_PAGE
* @see javax.servlet.jsp.PageContext#setAttribute
*/
public void setScope(String scope) {
this.scope = scope;
}
protected final int doStartTagInternal() throws JspException {
Object resolvedValue = this.value;
if (this.value instanceof String) {
String strValue = (String) this.value;
resolvedValue = ExpressionEvaluationUtils.evaluate("value", strValue, pageContext);
}
if (resolvedValue != null) {
// Find the BindTag, if applicable.
BindTag tag = (BindTag) TagSupport.findAncestorWithClass(this, BindTag.class);
if (tag == null) {
// The tag can only be used within a BindTag.
throw new JspException("TransformTag can only be used within BindTag");
}
// OK, get the property editor.
PropertyEditor editor = tag.getEditor();
String result = null;
if (editor != null) {
// If an editor was found, edit the value.
editor.setValue(resolvedValue);
result = editor.getAsText();
}
else {
// Else, just do a toString.
result = resolvedValue.toString();
}
result = isHtmlEscape() ? HtmlUtils.htmlEscape(result) : result;
String resolvedVar = ExpressionEvaluationUtils.evaluateString("var", this.var, pageContext);
if (resolvedVar != null) {
String resolvedScope = ExpressionEvaluationUtils.evaluateString("scope", this.scope, pageContext);
pageContext.setAttribute(resolvedVar, result, TagUtils.getScope(resolvedScope));
}
else {
try {
// Else, just print it out.
pageContext.getOut().print(result);
}
catch (IOException ex) {
throw new JspException(ex);
}
}
}
return SKIP_BODY;
}
}