/*
* Copyright 2002-2008 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.form;
import javax.servlet.jsp.JspException;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* Databinding-aware JSP tag for rendering an HTML '<code>label</code>' element
* that defines text that is associated with a single form element.
*
* <p>The {@link #setFor(String) 'for'} attribute is required.
*
* <p>See the "formTags" showcase application that ships with the
* full Spring distribution for an example of this class in action.
*
* @author Rob Harrop
* @author Juergen Hoeller
* @since 2.0
*/
public class LabelTag extends AbstractHtmlElementTag {
/**
* The HTML '<code>label</code>' tag.
*/
private static final String LABEL_TAG = "label";
/**
* The name of the '<code>for</code>' attribute.
*/
private static final String FOR_ATTRIBUTE = "for";
/**
* The {@link TagWriter} instance being used.
* <p>Stored so we can close the tag on {@link #doEndTag()}.
*/
private TagWriter tagWriter;
/**
* The value of the '<code>for</code>' attribute.
*/
private String forId;
/**
* Set the value of the '<code>for</code>' attribute.
* <p>Defaults to the value of {@link #getPath}; may be a runtime expression.
* @throws IllegalArgumentException if the supplied value is <code>null</code>
*/
public void setFor(String forId) {
Assert.notNull(forId, "'forId' must not be null");
this.forId = forId;
}
/**
* Get the value of the '<code>id</code>' attribute.
* <p>May be a runtime expression.
*/
public String getFor() {
return this.forId;
}
/**
* Writes the opening '<code>label</code>' tag and forces a block tag so
* that body content is written correctly.
* @return {@link javax.servlet.jsp.tagext.Tag#EVAL_BODY_INCLUDE}
*/
@Override
protected int writeTagContent(TagWriter tagWriter) throws JspException {
tagWriter.startTag(LABEL_TAG);
tagWriter.writeAttribute(FOR_ATTRIBUTE, resolveFor());
writeDefaultAttributes(tagWriter);
tagWriter.forceBlock();
this.tagWriter = tagWriter;
return EVAL_BODY_INCLUDE;
}
/**
* Overrides {@link #getName()} to always return <code>null</code>,
* because the '<code>name</code>' attribute is not supported by the
* '<code>label</code>' tag.
* @return the value for the HTML '<code>name</code>' attribute
*/
@Override
protected String getName() throws JspException {
// This also suppresses the 'id' attribute (which is okay for a <label/>)
return null;
}
/**
* Determine the '<code>for</code>' attribute value for this tag,
* autogenerating one if none specified.
* @see #getFor()
* @see #autogenerateFor()
*/
protected String resolveFor() throws JspException {
if (StringUtils.hasText(this.forId)) {
return getDisplayString(evaluate(FOR_ATTRIBUTE, this.forId));
}
else {
return autogenerateFor();
}
}
/**
* Autogenerate the '<code>for</code>' attribute value for this tag.
* <p>The default implementation delegates to {@link #getPropertyPath()},
* deleting invalid characters (such as "[" or "]").
*/
protected String autogenerateFor() throws JspException {
return StringUtils.deleteAny(getPropertyPath(), "[]");
}
/**
* Close the '<code>label</code>' tag.
*/
@Override
public int doEndTag() throws JspException {
this.tagWriter.endTag();
return EVAL_PAGE;
}
/**
* Disposes of the {@link TagWriter} instance.
*/
@Override
public void doFinally() {
super.doFinally();
this.tagWriter = null;
}
}
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