org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag Maven / Gradle / Ivy
/*
* Copyright 2002-2007 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 java.beans.PropertyEditor;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import org.springframework.beans.PropertyAccessor;
import org.springframework.core.Conventions;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.support.BindStatus;
import org.springframework.web.servlet.tags.NestedPathTag;
/**
* Base tag for all data-binding aware JSP form tags.
*
* Provides the common {@link #setPath path} and {@link #setId id} properties.
* Provides sub-classes with utility methods for accessing the {@link BindStatus}
* of their bound value and also for {@link #writeOptionalAttribute interacting}
* with the {@link TagWriter}.
*
* @author Rob Harrop
* @author Juergen Hoeller
* @since 2.0
*/
public abstract class AbstractDataBoundFormElementTag extends AbstractFormTag {
/**
* The 'id' attribute of the rendered HTML tag.
*/
public static final String ID_ATTRIBUTE = "id";
/**
* The name of the 'commandName' attribute.
*/
public static final String COMMAND_NAME_ATTRIBUTE = "commandName";
/**
* The name of the {@link javax.servlet.jsp.PageContext} attribute under which the
* command object name is exposed.
*/
public static final String COMMAND_NAME_VARIABLE_NAME =
Conventions.getQualifiedAttributeName(AbstractFormTag.class, COMMAND_NAME_ATTRIBUTE);
/**
* The property path from the {@link FormTag#setCommandName command object}.
*/
private String path;
/**
* The value of the 'id' attribute.
*/
private String id;
/**
* The {@link BindStatus} of this tag.
*/
private BindStatus bindStatus;
/**
* Set the property path from the {@link FormTag#setCommandName command object}.
* May be a runtime expression. Required.
*/
public void setPath(String path) {
Assert.hasText(path, "'path' must not be empty");
this.path = path;
}
/**
* Get the {@link #evaluate resolved} property path for the
* {@link FormTag#setCommandName command object}.
*/
protected final String getPath() throws JspException {
return (String) evaluate("path", this.path);
}
/**
* Set the value of the 'id' attribute.
*
Defaults to the value of {@link #getName}; may be a runtime expression.
* Note that the default value may not be valid for certain tags.
*/
public void setId(String id) {
this.id = id;
}
/**
* Get the value of the 'id' attribute.
*
May be a runtime expression.
*/
public String getId() {
return this.id;
}
/**
* Writes the default set of attributes to the supplied {@link TagWriter}.
* Further abstract sub-classes should override this method to add in
* any additional default attributes but must remember
* to call the super method.
*
Concrete sub-classes should call this method when/if they want
* to render default attributes.
* @param tagWriter the {@link TagWriter} to which any attributes are to be {@link TagWriter#writeAttribute(String, String) written}
*/
protected void writeDefaultAttributes(TagWriter tagWriter) throws JspException {
String id = getId();
if (StringUtils.hasText(id)) {
tagWriter.writeAttribute(ID_ATTRIBUTE, ObjectUtils.getDisplayString(evaluate(ID_ATTRIBUTE, id)));
}
else {
writeOptionalAttribute(tagWriter, ID_ATTRIBUTE, autogenerateId());
}
writeOptionalAttribute(tagWriter, "name", getName());
}
/**
* Autogenerate the 'id' attribute value for this tag.
*
The default implementation simply delegates to {@link #getName}.
*/
protected String autogenerateId() throws JspException {
return getName();
}
/**
* Get the value for the HTML 'name' attribute.
*
The default implementation simply delegates to
* {@link #getCompletePath()} to use the property path as the name.
* For the most part this is desirable as it links with the server-side
* expectation for databinding. However, some subclasses may wish to change
* the value of the 'name' attribute without changing the bind path.
* @return the value for the HTML 'name' attribute
*/
protected String getName() throws JspException {
return getCompletePath();
}
/**
* Get the bound value.
* @see #getBindStatus()
*/
protected final Object getBoundValue() throws JspException {
return getBindStatus().getValue();
}
/**
* Get the {@link PropertyEditor}, if any, in use for value bound to this tag.
*/
protected PropertyEditor getPropertyEditor() throws JspException {
return getBindStatus().getEditor();
}
/**
* Get the {@link BindStatus} for this tag.
*/
protected BindStatus getBindStatus() throws JspException {
if (this.bindStatus == null) {
String resolvedPropertyPath = getPath();
String bindPath = getBindPath(resolvedPropertyPath);
// HTML escaping in tags is performed by the ValueFormatter class.
this.bindStatus = new BindStatus(getRequestContext(), bindPath, false);
}
return this.bindStatus;
}
/**
* Get the final bind path including the exposed {@link FormTag command name} and
* any {@link NestedPathTag nested paths}.
*/
private String getBindPath(String resolvedSubPath) {
StringBuffer sb = new StringBuffer();
addBindPathElement(sb, getCommandName());
addBindPathElement(sb, getNestedPath());
addBindPathElement(sb, resolvedSubPath);
return sb.toString();
}
private void addBindPathElement(StringBuffer sb, String pathElement) {
if (StringUtils.hasLength(pathElement)) {
int length = sb.length();
if (length > 0 && sb.charAt(length - 1) != PropertyAccessor.NESTED_PROPERTY_SEPARATOR_CHAR) {
sb.append(PropertyAccessor.NESTED_PROPERTY_SEPARATOR_CHAR);
}
sb.append(pathElement);
}
}
/**
* Get the value of the nested path that may have been exposed by the
* {@link NestedPathTag}.
*/
protected String getNestedPath() {
return (String) this.pageContext.getAttribute(NestedPathTag.NESTED_PATH_VARIABLE_NAME, PageContext.REQUEST_SCOPE);
}
/**
* Build the complete path for this tag, including the nested path.
* @see #getNestedPath()
* @see #getPath()
*/
protected String getCompletePath() throws JspException {
String nestedPath = getNestedPath();
return (nestedPath != null ? nestedPath + getPath() : getPath());
}
private String getCommandName() {
return (String) this.pageContext.getAttribute(COMMAND_NAME_VARIABLE_NAME, PageContext.REQUEST_SCOPE);
}
/**
* Disposes of the {@link BindStatus} instance.
*/
public void doFinally() {
super.doFinally();
this.bindStatus = null;
}
}