ActionForms are beans that represent
an HTML form. In struts-config.xml,
we defined a single ActionFormBean:
ShowRecipeForm.
001 /*
002 * ShowRecipeForm.java created on Apr 27, 2005 at 2:21:36 PM
003 *
004 * strutsExample is a simple web application that allows a user to search and
005 * view a set of recipes. Copyright (C) 2005 SkillFusion Software
006 *
007 * This program is free software; you can redistribute it and/or modify it under
008 * the terms of the GNU General Public License as published by the Free Software
009 * Foundation; either version 2 of the License, or (at your option) any later
010 * version.
011 *
012 * This program is distributed in the hope that it will be useful, but WITHOUT
013 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
014 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
015 * details.
016 *
017 * You should have received a copy of the GNU General Public License along with
018 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
019 * Place - Suite 330, Boston, MA 02111-1307, USA
020 */
021 package com.skillfusion.examples.struts.forms;
022
023 import org.apache.commons.logging.Log;
024 import org.apache.commons.logging.LogFactory;
025
026 import javax.servlet.http.HttpServletRequest;
027
028 import org.apache.struts.action.ActionErrors;
029 import org.apache.struts.action.ActionForm;
030 import org.apache.struts.action.ActionMapping;
031 import org.apache.struts.action.ActionMessage;
032 import org.apache.struts.action.ActionMessages;
033
034 /**
035 * This is a simple form bean to do some validation on the data processed by
036 * <code>ShowRecipeAction</code>.
037 *
038 * @author hank
039 */
040 public final class ShowRecipeForm extends ActionForm {
041 /**
042 * Logger for this class.
043 */
044 private static final Log LOGGER = LogFactory.getLog(ShowRecipeForm.class);
045
046 /**
047 * The underlying field for the <tt>Name</tt> input on the <tt>.jsp</tt>.
048 */
049 private String name;
050
051 /**
052 * Retrieves a reference to <code>name</code>.
053 *
054 * @return The <code>String</code> stored in <code>name</code>.
055 */
056 public String getName() {
057 if (LOGGER.isTraceEnabled()) {
058 LOGGER.trace("getName() - start");
059 }
060
061 if (LOGGER.isTraceEnabled()) {
062 LOGGER.trace("getName() - end - return value = " + this.name);
063 }
064 return this.name;
065 }
066
067 /**
068 * Sets the value of <code>name</code>.
069 *
070 * @param newName
071 * A <code>String</code> containing the new value for
072 * <code>name</code>.
073 */
074 public void setName(final String newName) {
075 if (LOGGER.isTraceEnabled()) {
076 LOGGER.trace("setName(String newName = " + newName + ") - start");
077 }
078
079 this.name = newName;
080
081 if (LOGGER.isTraceEnabled()) {
082 LOGGER.trace("setName(String newName = " + newName + ") - end");
083 }
084 }
085
086 /**
087 * Simple form bean validation, this method just makes sure that the name is
088 * neither <tt>null</tt> or an empty <code>String</code>. In the
089 * future, this method may be replaced by using the declarative validation
090 * approach afforded by Validator.
091 *
092 * @param mapping
093 * The mapping used to select this instance
094 * @param request
095 * The HTTP request we are processing
096 * @return A collection of the validate errors we found.
097 * @see org.apache.struts.action.ActionForm#validate(org.apache.struts.action.ActionMapping,
098 * javax.servlet.http.HttpServletRequest)
099 */
100 public ActionErrors validate(final ActionMapping mapping,
101 final HttpServletRequest request) {
102 if (LOGGER.isTraceEnabled()) {
103 LOGGER
104 .trace("validate(ActionMapping mapping = " + mapping
105 + ", HttpServletRequest request = " + request
106 + ") - start");
107 }
108
109 // Set up our return variable
110 ActionErrors toReturn = new ActionErrors();
111
112 // Merge in the results of our superclass's validate function
113 toReturn.add(super.validate(mapping, request));
114
115 // If name is null (or empty string), add an error message
116 if (null == this.getName() || 0 == this.getName().length()) {
117 toReturn.add(ActionMessages.GLOBAL_MESSAGE, new ActionMessage(
118 "error.required.name"));
119 }
120
121 ActionErrors returnActionErrors = super.validate(mapping, request);
122 if (LOGGER.isTraceEnabled()) {
123 LOGGER.trace("validate(ActionMapping mapping = " + mapping
124 + ", HttpServletRequest request = " + request
125 + ") - end - return value = " + returnActionErrors);
126 }
127 return returnActionErrors;
128 }
129 }
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Each element of the HTML form
corresponds to a property on the bean. In the case
of ShowRecipeForm, that means it has a
single property: name. In addition to
the getter and setter for name, there
is also a
validate(ActionMapping, HttpServletRequest)
function, which begins on line 100. This method is
invoked when you submit the HTML form corresponding
to this ActionForm. There is a default
implementation that does no actual validation and is
suitable if you wish to skip validation or set up
declarative validation, but you can also override it
to perform the actual validation, as we have here.
While declarative validation is the most popular
choice, setting it up requires more overhead than
can be justified for just one form. In
ShowRecipeForm, we set up the
validate() method to add an error
message to the request if the user did not enter a
name on the HTML form.
