Validator 验证 - 概述

 

对表单的验证有两种：语法验证和语义验证。语法有效是指数据必须有正确的格式，如数据只能包含数字，语义有效是指必须符合逻辑，如时间值不能是一个未来的时间。

 

struts1.2 增添了许多新特征如： validwhen 验证规则 (validator)

 

一开始 Struts 是使用 formbean 的 validate() 方法进行验证的。有时候则是在 Action 中进行验证。通过 validator 框架你可以不需要通过硬编码的方式进行验证，它使你可以在一个 XML 中配置对表单的验证，这样做可以很灵活的添加修改删除验证，同时可以重复使用验证规则。你可以使用它在客户端进行基于 javascript 和服务器端的验证，你也可以自定义验证方法。

 

具体的验证规则如下：

required	Checks that a field value is non-null and not an empty string.
requiredif	Only available for Struts 1.1. This validator allows one field to be specified as required if another field is null, not null, or equal to a specified value. This validator is deprecated, in favor of validwhen, in releases after Struts 1.1.
validwhen	Designed to replace requiredif, this validator is available in releases after Struts 1.1. This validator relies on a user-specified test expression that can include references to other fields, field values, and logical relationships.
minlength	Checks that the number of characters in the field value is greater than or equal to a specified minimum.
maxlength	Checks that the number of characters in the field value is less than or equal to a specified maximum.
mask	Validates the field value using a regular expression to determine a match. If the value matches the regular expression, the field is valid.
byte	Checks that the field value is a valid byte value.
short	Checks that the field value is a valid short integer value.
integer	Checks that the field value is a valid integer value.
long	Checks that the field value is a valid long value.
float	Checks that the field value is a valid floating-point value.
double	Checks that the field value is a valid double value.
date	Checks that the field value matches a specified date format pattern (e.g., MM/dd/yyyy). The match can be strict or lenient; "strict" would require May 10, 1963 to be formatted (using the MM/dd/yyyy pattern) as 05/10/1963; "lenient" would allow 5/10/1963.
range	Checks that the field value is within a specified numeric range. This valdiator has been deprecated in favor of the type-specific range checks (intRange, floatRange, etc.).
intRange	Checks that the field value is within a range bounded by two int values.
floatRange	Checks that the field value is within a range bounded by two float values.
doubleRange	Checks that the field value is within a range bounded by two double values.
creditCard	Verifies that the format of the field value is valid for a credit card number. This validator is convenient to use instead of using mask.
email	Verifies that the format of the field value is valid for an electronic mail address (e.g., [e-mail]). This validator is convenient to use instead of working with mask.
url	Verifies that the value entered is a valid uniform resource locator. Use this validator when you want to validate an input web location or hyperlink value.

 

要使用 Validator 验证框架，首先必须在 struts-config.xml 中指定 plug-in 元素。

<plug-in className="org.apache.struts.validator.ValidatorPlugIn">     <set-property property="pathnames"                      value="/WEB-INF/validator-rules.xml,                             /WEB-INF/validation.xml"/> </plug-in>

 

 

 

 

 

 

pathnames 指定你要使用的 Validator 配置文件。可以设置一个或多个。第一个 validator-rules.xml 定义

各个验证规则 , 第二个 validation.xml 定义了验证框架如何应用到你的应用程序中去。

一个好的方法是为应用程序的每个功能模块定义一个 validation.xml 。一个大型的应用程序可能有一大堆这样的文件

要使用验证框架的 form bean ，如果是硬编码的 formbean 则必须继承 org.apache.struts.action.ValidatorForm 。如果是动态 formbean 则必须是 org.apache.struts.action.DynaValidatorForm 或它的字类。

下面一个实例验证 MyLoginForm 表单的 username 和 password 字段是否为空，并限制 password 的最大值和最小值

 

<?xml version="1.0" encoding="ISO-8859-1" ?>

<!DOCTYPE form-validation PUBLIC

 "-//Apache Software Foundation//DTD Commons Validator Rules

 Configuration 1.1//EN"

 "http://jakarta.apache.org/commons/dtds/validator_1_1_3.dtd">

<form-validation>

    <formset>

        <form name="MyLoginForm">

            <field property="username"

                    depends="required">

                <arg key="prompt.username"/>

            </field>

            <field property="password"

                    depends="required, minlength,maxlength">

                <arg key="prompt.password"/>

                <arg key="${var:minlength}" name="minlength"

                   resource="false"/>

                <arg key="${var:maxlength}" name="maxlength"

                   resource="false"/>

                <var>

                    <var-name>maxlength</var-name>

                    <var-value>16</var-value>

                </var>

                <var>

                    <var-name>minlength</var-name>

                    <var-value>3</var-value>

                </var>

            </field>

        </form>

    <formset>

<form-validation>

form 元素中的 name 属性指定要验证的表单名而不是类。

 

 

如果 formbean 的类型为 ValidatorActionForm 或 DynaValidatorActionForm ，则验证就和请求路径关联而不是 formbean 。当一个表单被提交到一个 Action 时，只有与路径对应的验证起作用。举例如下：

 

<form name="/ProcessStep1">

    <field property="username"

            depends="required">

        <arg key="prompt.username"/>

    </field>

</form>

<form name="/ProcessStep2>

    <field property="password"

            depends="required">

        <arg key="prompt.password"/>

    </field>

</form>

只有当 struts-config.xml 的 action 元素的 validate 属性为 true 时才进行验证（ validate 默认值为 true ）。如果验证失败则 Struts 跳转到由 action 元素的 input 属性指定的位置。

<action    path="/Login"

           type="com.oreilly.strutsckbk.ch08.LoginAction"

          scope="request"

           name="MyLoginForm"

        validate="true"

          input="/login.jsp">

    <forward name="success" path="/login_success.jsp"/>

</action>