1 /* 2 * $Id$ 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, 15 * software distributed under the License is distributed on an 16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 17 * KIND, either express or implied. See the License for the 18 * specific language governing permissions and limitations 19 * under the License. 20 */ 21 package org.apache.struts.action; 22 23 import org.apache.struts.upload.MultipartRequestHandler; 24 25 import jakarta.servlet.ServletRequest; 26 import jakarta.servlet.http.HttpServletRequest; 27 28 import java.io.Serializable; 29 30 /** 31 * <p>An <strong>ActionForm</strong> is a JavaBean optionally associated with 32 * one or more <code>ActionMappings</code>. Such a bean will have had its 33 * properties initialized from the corresponding request parameters before the 34 * corresponding <code>Action.execute</code> method is called.</p> 35 * 36 * <p>When the properties of this bean have been populated, but before the 37 * <code>execute</code> method of the <code>Action</code> is called, this 38 * bean's <code>validate</code> method will be called, which gives the bean a 39 * chance to verify that the properties submitted by the user are correct and 40 * valid. If this method finds problems, it returns an error messages object 41 * that encapsulates those problems, and the controller servlet will return 42 * control to the corresponding input form. Otherwise, the 43 * <code>validate</code> method returns <code>null</code>, indicating that 44 * everything is acceptable and the corresponding <code>Action.execute</code> 45 * method should be called.</p> 46 * 47 * <p>This class must be subclassed in order to be instantiated. Subclasses 48 * should provide property getter and setter methods for all of the bean 49 * properties they wish to expose, plus override any of the public or 50 * protected methods for which they wish to provide modified functionality. 51 * </p> 52 * 53 * <p>Because ActionForms are JavaBeans, subclasses should also implement 54 * <code>Serializable</code>, as required by the JavaBean specification. Some 55 * containers require that an object meet all JavaBean requirements in order 56 * to use the introspection API upon which ActionForms rely.</p> 57 * 58 * @version $Rev$ $Date: 2005-11-12 08:14:24 -0500 (Sat, 12 Nov 2005) 59 * $ 60 */ 61 public abstract class ActionForm implements Serializable { 62 private static final long serialVersionUID = -7986260744524429895L; 63 64 // ----------------------------------------------------- Instance Variables 65 66 /** 67 * <p>The servlet instance to which we are attached.</p> 68 */ 69 protected transient ActionServlet servlet = null; 70 71 /** 72 * <p>The MultipartRequestHandler for this form, can be 73 * <code>null</code>.</p> 74 */ 75 protected transient MultipartRequestHandler multipartRequestHandler; 76 77 // ------------------------------------------------------------- Properties 78 79 /** 80 * <p>Return the servlet instance to which we are attached.</p> 81 * 82 * @return The servlet instance to which we are attached. 83 */ 84 protected ActionServlet getServlet() { 85 return (this.servlet); 86 } 87 88 /** 89 * <p>Return the controller servlet instance to which we are attached. as 90 * an <code>ActionServletWrapper</code>.</p> 91 * 92 * @return An instance of {@link ActionServletWrapper} 93 * @see ActionServletWrapper 94 * @since Struts 1.0.1 95 */ 96 public ActionServletWrapper getServletWrapper() { 97 return new ActionServletWrapper(getServlet()); 98 } 99 100 /** 101 * <p>Return the <code>MultipartRequestHandler</code> for this form The 102 * reasoning behind this is to give form bean developers control over the 103 * lifecycle of their multipart requests through the use of the 104 * <code>finish</code> and/or <code>rollback</code> methods of 105 * <code>MultipartRequestHandler</code>. This method will return 106 * <code>null</code> if this form's enctype is not "multipart/form-data". 107 * </p> 108 * 109 * @return The {@link org.apache.struts.upload.MultipartRequestHandler} 110 * for this form. 111 * @see org.apache.struts.upload.MultipartRequestHandler 112 */ 113 public MultipartRequestHandler getMultipartRequestHandler() { 114 return multipartRequestHandler; 115 } 116 117 /** 118 * <p>Set the servlet instance to which we are attached (if 119 * <code>servlet</code> is non-null).</p> 120 * 121 * @param servlet The new controller servlet, if any 122 */ 123 public void setServlet(ActionServlet servlet) { 124 this.servlet = servlet; 125 126 // :FIXME: Should this be releasing resources? 127 } 128 129 /** 130 * <p>Set the Handler provided for use in dealing with file uploads.</p> 131 * 132 * @param multipartRequestHandler The Handler to use for fileuploads. 133 */ 134 public void setMultipartRequestHandler( 135 MultipartRequestHandler multipartRequestHandler) { 136 this.multipartRequestHandler = multipartRequestHandler; 137 } 138 139 // --------------------------------------------------------- Public Methods 140 141 /** 142 * <p>Can be used to reset all bean properties to their default state. 143 * This method is called before the properties are repopulated by the 144 * controller.</p> 145 * 146 * <p>The default implementation attempts to forward to the HTTP version 147 * of this method.</p> 148 * 149 * @param mapping The mapping used to select this instance 150 * @param request The servlet request we are processing 151 */ 152 public void reset(ActionMapping mapping, ServletRequest request) { 153 try { 154 reset(mapping, (HttpServletRequest) request); 155 } catch (ClassCastException e) { 156 ; // FIXME: Why would this ever happen except a null 157 } 158 } 159 160 /** 161 * <p>Can be used to reset bean properties to their default state, as 162 * needed. This method is called before the properties are repopulated by 163 * the controller.</p> 164 * 165 * <p>The default implementation does nothing. In practice, the only 166 * properties that need to be reset are those which represent checkboxes 167 * on a session-scoped form. Otherwise, properties can be given initial 168 * values where the field is declared. </p> 169 * 170 * <p>If the form is stored in session-scope so that values can be 171 * collected over multiple requests (a "wizard"), you must be very careful 172 * of which properties, if any, are reset. As mentioned, session-scope 173 * checkboxes must be reset to false for any page where this property is 174 * set. This is because the client does not submit a checkbox value when 175 * it is clear (false). If a session-scoped checkbox is not proactively 176 * reset, it can never be set to false.</p> 177 * 178 * <p>This method is <strong>not</strong> the appropriate place to 179 * initialize form value for an "update" type page (this should be done in 180 * a setup Action). You mainly need to worry about setting checkbox values 181 * to false; most of the time you can leave this method unimplemented. 182 * </p> 183 * 184 * @param mapping The mapping used to select this instance 185 * @param request The servlet request we are processing 186 */ 187 public void reset(ActionMapping mapping, HttpServletRequest request) { 188 // Default implementation does nothing 189 } 190 191 /** 192 * <p>Can be used to validate the properties that have been set for this 193 * non-HTTP request, and return an <code>ActionErrors</code> object that 194 * encapsulates any validation errors that have been found. If no errors 195 * are found, return <code>null</code> or an <code>ActionErrors</code> 196 * object with no recorded error messages.</p> 197 * 198 * <p>The default implementation attempts to forward to the HTTP version 199 * of this method.</p> 200 * 201 * @param mapping The mapping used to select this instance 202 * @param request The servlet request we are processing 203 * @return The set of validation errors, if validation failed; an empty 204 * set or <code>null</code> if validation succeeded. 205 */ 206 public ActionErrors validate(ActionMapping mapping, ServletRequest request) { 207 try { 208 return (validate(mapping, (HttpServletRequest) request)); 209 } catch (ClassCastException e) { 210 return (null); 211 } 212 } 213 214 /** 215 * <p>Can be used to validate the properties that have been set for this 216 * HTTP request, and return an <code>ActionErrors</code> object that 217 * encapsulates any validation errors that have been found. If no errors 218 * are found, return <code>null</code> or an <code>ActionErrors</code> 219 * object with no recorded error messages.</p> 220 * 221 * <p>The default implementation performs no validation and returns 222 * <code>null</code>. Subclasses must override this method to provide any 223 * validation they wish to perform.</p> 224 * 225 * @param mapping The mapping used to select this instance 226 * @param request The servlet request we are processing 227 * @return The set of validation errors, if validation failed; an empty 228 * set or <code>null</code> if validation succeeded. 229 * @see DynaActionForm 230 */ 231 public ActionErrors validate(ActionMapping mapping, 232 HttpServletRequest request) { 233 return (null); 234 } 235 }