1 package com.opensymphony.xwork2.validator;
2
3 /**
4 * ValidatorFactory
5 *
6 * <p>
7 * <!-- START SNIPPET: javadoc -->
8 * Validation rules are handled by validators, which must be registered with
9 * the ValidatorFactory (using the registerValidator method). The simplest way to do so is to add a file name
10 * validators.xml in the root of the classpath (/WEB-INF/classes) that declares
11 * all the validators you intend to use.
12 * <!-- END SNIPPET: javadoc -->
13 * </p>
14 *
15 *
16 * <p>
17 * <b>INFORMATION</b>
18 * <!-- START SNIPPET: information -->
19 * validators.xml if being defined should be available in the classpath. However
20 * this is not necessary, if no custom validator is needed. Predefined sets of validators
21 * will automatically be picked up when defined in
22 * com/opensymphony/xwork2/validator/validators/default.xml packaged in
23 * in the xwork jar file. See ValidatorFactory static block for details.
24 * <!-- END SNIPPET: information -->
25 * </p>
26 *
27 * <p>
28 * <b>WARNING</b>
29 * <!-- START SNIPPET: warning -->
30 * If custom validator is being defined and a validators.xml is created and
31 * place in the classpath, do remember to copy all the other pre-defined validators
32 * that is needed into the validators.xml as if not they will not be registered.
33 * Once a validators.xml is detected in the classpath, the default one
34 * (com/opensymphony/xwork2/validator/validators/default.xml) will not be loaded.
35 * It is only loaded when a custom validators.xml cannot be found in the classpath.
36 * Be careful.
37 * <!-- END SNIPPET: warning -->
38 * </p>
39 *
40 * <p><b>Note:</b>
41 * <!-- START SNIPPET: turningOnValidators -->
42 * The default validationWorkflowStack already includes this.<br/>
43 * All that is required to enable validation for an Action is to put the
44 * ValidationInterceptor in the interceptor refs of the action (see xwork.xml) like so:
45 * <!-- END SNIPPET: turningOnValidators -->
46 * </p>
47 *
48 * <pre>
49 * <!-- START SNIPPET: exTurnOnValidators -->
50 * <interceptor name="validator" class="com.opensymphony.xwork2.validator.ValidationInterceptor"/>
51 * <!-- END SNIPPET: exTurnOnValidators -->
52 * </pre>
53 *
54 * <p><b>Field Validators</b>
55 * <!-- START SNIPPET: fieldValidators -->
56 * Field validators, as the name indicate, act on single fields accessible through an action.
57 * A validator, in contrast, is more generic and can do validations in the full action context,
58 * involving more than one field (or even no field at all) in validation rule.
59 * Most validations can be defined on per field basis. This should be preferred over
60 * non-field validation wherever possible, as field validator messages are bound to the
61 * related field and will be presented next to the corresponding input element in the
62 * respecting view.
63 * <!-- END SNIPPET: fieldValidators -->
64 * </p>
65 *
66 * <p><b>Non Field Validators</b>
67 * <!-- START SNIPPET: nonFieldValidators -->
68 * Non-field validators only add action level messages. Non-field validators
69 * are mostly domain specific and therefore offer custom implementations.
70 * The most important standard non-field validator provided by XWork
71 * is ExpressionValidator.
72 * <!-- END SNIPPET: nonFieldValidators -->
73 * </p>
74 *
75 * <p><b>NOTE:</b>
76 * <!-- START SNIPPET: validatorsNote -->
77 * Non-field validators takes precedence over field validators
78 * regardless of the order they are defined in *-validation.xml. If a non-field
79 * validator is short-circuited, it will causes its non-field validator to not
80 * being executed. See validation framework documentation for more info.
81 * <!-- END SNIPPET: validatorsNote -->
82 * </p>
83 *
84 * <p><b>VALIDATION RULES:</b>
85 * <!-- START SNIPPET: validationRules1 -->
86 * Validation rules can be specified:
87 * <ol>
88 * <li> Per Action class: in a file named ActionName-validation.xml</li>
89 * <li> Per Action alias: in a file named ActionName-alias-validation.xml</li>
90 * <li> Inheritance hierarchy and interfaces implemented by Action class:
91 * XWork searches up the inheritance tree of the action to find default
92 * validations for parent classes of the Action and interfaces implemented</li>
93 * </ol>
94 * Here is an example for SimpleAction-validation.xml:
95 * <!-- END SNIPPET: validationRules1 -->
96 * <p>
97 *
98 * <pre>
99 * <!-- START SNIPPET: exValidationRules1 -->
100 * <!DOCTYPE validators PUBLIC "-//OpenSymphony Group//XWork Validator 1.0.2//EN"
101 * "http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">
102 * <validators>
103 * <field name="bar">
104 * <field-validator type="required">
105 * <message>You must enter a value for bar.</message>
106 * </field-validator>
107 * <field-validator type="int">
108 * <param name="min">6</param>
109 * <param name="max">10</param>
110 * <message>bar must be between ${min} and ${max}, current value is ${bar}.</message>
111 * </field-validator>
112 * </field>
113 * <field name="bar2">
114 * <field-validator type="regex">
115 * <param name="expression">[0-9],[0-9]</param>
116 * <message>The value of bar2 must be in the format "x, y", where x and y are between 0 and 9</message>
117 * </field-validator>
118 * </field>
119 * <field name="date">
120 * <field-validator type="date">
121 * <param name="min">12/22/2002</param>
122 * <param name="max">12/25/2002</param>
123 * <message>The date must be between 12-22-2002 and 12-25-2002.</message>
124 * </field-validator>
125 * </field>
126 * <field name="foo">
127 * <field-validator type="int">
128 * <param name="min">0</param>
129 * <param name="max">100</param>
130 * <message key="foo.range">Could not find foo.range!</message>
131 * </field-validator>
132 * </field>
133 * <validator type="expression">
134 * <param name="expression">foo lt bar </param>
135 * <message>Foo must be greater than Bar. Foo = ${foo}, Bar = ${bar}.</message>
136 * </validator>
137 * </validators>
138 * <!-- END SNIPPET: exValidationRules1 -->
139 * </pre>
140 *
141 *
142 * <p>
143 * <!-- START SNIPPET: validationRules2 -->
144 * Here we can see the configuration of validators for the SimpleAction class.
145 * Validators (and field-validators) must have a type attribute, which refers
146 * to a name of an Validator registered with the ValidatorFactory as above.
147 * Validator elements may also have <param> elements with name and value attributes
148 * to set arbitrary parameters into the Validator instance. See below for discussion
149 * of the message element.
150 * <!-- END SNIPPET: validationRules2 -->
151 * </p>
152 *
153 *
154 *
155 * <!-- START SNIPPET: validationRules3 -->
156 * <p>Each Validator or Field-Validator element must define one message element inside
157 * the validator element body. The message element has 1 attributes, key which is not
158 * required. The body of the message tag is taken as the default message which should
159 * be added to the Action if the validator fails. Key gives a message key to look up
160 * in the Action's ResourceBundles using getText() from LocaleAware if the Action
161 * implements that interface (as ActionSupport does). This provides for Localized
162 * messages based on the Locale of the user making the request (or whatever Locale
163 * you've set into the LocaleAware Action). After either retrieving the message from
164 * the ResourceBundle using the Key value, or using the Default message, the current
165 * Validator is pushed onto the ValueStack, then the message is parsed for \$\{...\}
166 * sections which are replaced with the evaluated value of the string between the
167 * \$\{ and \}. This allows you to parameterize your messages with values from the
168 * Validator, the Action, or both.</p>
169 *
170 *
171 * <p>If the validator fails, the validator is pushed onto the ValueStack and the
172 * message - either the default or the locale-specific one if the key attribute is
173 * defined (and such a message exists) - is parsed for ${...} sections which are
174 * replaced with the evaluated value of the string between the ${ and }. This
175 * allows you to parameterize your messages with values from the validator, the
176 * Action, or both. </p>
177 *
178 * <p><b>NOTE:</b> Since validation rules are in an XML file, you must make sure
179 * you escape special characters. For example, notice that in the expression
180 * validator rule above we use "&gt;" instead of ">". Consult a resource on XML
181 * for the full list of characters that must be escaped. The most commonly used
182 * characters that must be escaped are: & (use &amp;), > (user &gt;), and < (use &lt;).</p>
183 *
184 * <p>Here is an example of a parameterized message:</p>
185 * <p>This will pull the min and max parameters from the IntRangeFieldValidator and
186 * the value of bar from the Action.</p>
187 * <!-- END SNIPPET: validationRules3 -->
188 *
189 * <pre>
190 * <!-- START SNIPPET: exValidationRules3 -->
191 * bar must be between ${min} and ${max}, current value is ${bar}.
192 * <!-- END SNIPPET: exValidationRules3 -->
193 * </pre>
194 *
195 * <!-- START SNIPPET: validationRules4 -->
196 * <p>Another notable fact is that the provided message value is capable of containing OGNL expressions.
197 * Keeping this in mind, it is possible to construct quite sophisticated messages.</p>
198 * <p>See the following example to get an impression:</p>
199 *
200 * <!-- END SNIPPET: validationRules4 -->
201 *
202 * <pre>
203 * <!-- START SNIPPET: exValidationRules4 -->
204 * <message>${getText("validation.failednotice")}! ${getText("reason")}: ${getText("validation.inputrequired")}</message>
205 * <!-- END SNIPPET: exValidationRules4 -->
206 * </pre>
207 *
208 * @version $Date$ $Id$
209 * @author Jason Carreira
210 * @author James House
211 */
212 public interface ValidatorFactory {
213
214 /**
215 * Get a Validator that matches the given configuration.
216 *
217 * @param cfg the configurator.
218 * @return the validator.
219 */
220 Validator getValidator(ValidatorConfig cfg);
221
222 /**
223 * Registers the given validator to the existing map of validators.
224 * This will <b>add</b> to the existing list.
225 *
226 * @param name name of validator to add.
227 * @param className the FQ classname of the validator.
228 */
229 void registerValidator(String name, String className);
230
231 /**
232 * Lookup to get the FQ classname of the given validator name.
233 *
234 * @param name name of validator to lookup.
235 * @return the found FQ classname
236 * @throws IllegalArgumentException is thrown if the name is not found.
237 */
238 String lookupRegisteredValidatorType(String name);
239 }
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