在Struts中使用Validator实现可配置的信息校验（一）

在Struts中对用户输入信息的校验一般在FromBean中进行（除非需要访问数据库进行诸如登录信息的校验，因为这是Action的工作），本文将阐述如何在Struts中实现可配置的信息校验。

一、在FormBean中手工实现

最简单的方法是直接在FormBean中重写ActionForm类的validate方法，validate方法签名如下：

public ActionErrors validate(ActionMapping mapping, HttpServletRequest req)

比如需要校验age字段必须填写数字：

 1public ActionErrors validate(ActionMapping mapping, HttpServletRequest req){
 2  ActionErrors errors = new ActionErrors();
 3
 4  String age = this.getAge();
 5  if(!this.isNumber(age)){ // isNumber() is not implemented
 6    errors.add(  ,  );
 7  }
 8
 9  return errors;
10}

在form提交后，容器会调用validate方法对表单数据进行校验，如果返回的ActionErrors为空（即校验通过），则将FormBean提交Action，否则重定向到提交form的页面。
这种方法实现简单，直观，容易测试、调试，但不可避免地存在以下缺点：

1、很难重用，导致重复开发
有很多校验逻辑在整个网站中是相同的，比如上述的数字校验，还有email校验、长度校验等等，而通过覆盖validate方法很难对这些校验过程进行重用，除非定义一些helper类封装校验方法（比如上述的isNumber()）。而当需要为另一个FormBean加入相同的校验逻辑时必须重复地覆盖validate方法

2、难于扩展
当要对一个表单增、删、改校验逻辑时必须修改validate方法，重新打包、部署

3、不可配置
因为校验逻辑硬编码于class文件中，运行时不可能做到灵活地配置校验逻辑

因此，Struts中加入了另一种更灵活的校验机制：

二、使用Validator

Validator提供了一种基于xml配置文件的校验模型，要使用这一模型必须做如下实现：

1、FormBean继承org.apache.struts.validator.ValidatorForm而不是ActionForm

2、不覆盖validate方法

3、创建validator-rules.xml及validation.xml文件
validator-rules.xml定义了可用来配置的校验逻辑，如：

  1<form-validation>
  2   <global>
  3      <validator name="required"
  4            classname="org.apache.struts.validator.FieldChecks"
  5               method="validateRequired"
  6         methodParams="java.lang.Object,
  7                       org.apache.commons.validator.ValidatorAction,
  8                       org.apache.commons.validator.Field,
  9                       org.apache.struts.action.ActionMessages,
 10                       org.apache.commons.validator.Validator,
 11                       javax.servlet.http.HttpServletRequest"
 12                  msg="errors.required"/>
 13      <validator name="requiredif"
 14                 classname="org.apache.struts.validator.FieldChecks"
 15                 method="validateRequiredIf"
 16                 methodParams="java.lang.Object,
 17                               org.apache.commons.validator.ValidatorAction,
 18                               org.apache.commons.validator.Field,
 19                               org.apache.struts.action.ActionMessages,
 20                               org.apache.commons.validator.Validator,
 21                               javax.servlet.http.HttpServletRequest"
 22                 msg="errors.required"/>
 23      <validator name="validwhen"
 24          msg="errors.required"
 25                 classname="org.apache.struts.validator.validwhen.ValidWhen"
 26                 method="validateValidWhen"
 27                 methodParams="java.lang.Object,
 28                       org.apache.commons.validator.ValidatorAction,
 29                       org.apache.commons.validator.Field,
 30                       org.apache.struts.action.ActionMessages,
 31                       org.apache.commons.validator.Validator,
 32                       javax.servlet.http.HttpServletRequest"/>
 33      <validator name="minlength"
 34            classname="org.apache.struts.validator.FieldChecks"
 35               method="validateMinLength"
 36         methodParams="java.lang.Object,
 37                       org.apache.commons.validator.ValidatorAction,
 38                       org.apache.commons.validator.Field,
 39                       org.apache.struts.action.ActionMessages,
 40                       org.apache.commons.validator.Validator,
 41                       javax.servlet.http.HttpServletRequest"
 42              depends=""
 43                  msg="errors.minlength"
 44           jsFunction="org.apache.commons.validator.javascript.validateMinLength"/>
 45      <validator name="maxlength"
 46            classname="org.apache.struts.validator.FieldChecks"
 47               method="validateMaxLength"
 48         methodParams="java.lang.Object,
 49                       org.apache.commons.validator.ValidatorAction,
 50                       org.apache.commons.validator.Field,
 51                       org.apache.struts.action.ActionMessages,
 52                       org.apache.commons.validator.Validator,
 53                       javax.servlet.http.HttpServletRequest"
 54              depends=""
 55                  msg="errors.maxlength"
 56           jsFunction="org.apache.commons.validator.javascript.validateMaxLength"/>
 57      <validator name="mask"
 58            classname="org.apache.struts.validator.FieldChecks"
 59               method="validateMask"
 60         methodParams="java.lang.Object,
 61                       org.apache.commons.validator.ValidatorAction,
 62                       org.apache.commons.validator.Field,
 63                       org.apache.struts.action.ActionMessages,
 64                       org.apache.commons.validator.Validator,
 65                       javax.servlet.http.HttpServletRequest"
 66              depends=""
 67                  msg="errors.invalid"/>
 68      <validator name="byte"
 69            classname="org.apache.struts.validator.FieldChecks"
 70               method="validateByte"
 71         methodParams="java.lang.Object,
 72                       org.apache.commons.validator.ValidatorAction,
 73                       org.apache.commons.validator.Field,
 74                       org.apache.struts.action.ActionMessages,
 75                       org.apache.commons.validator.Validator,
 76                       javax.servlet.http.HttpServletRequest"
 77              depends=""
 78                  msg="errors.byte"
 79       jsFunctionName="ByteValidations"/>
 80      <validator name="short"
 81            classname="org.apache.struts.validator.FieldChecks"
 82               method="validateShort"
 83         methodParams="java.lang.Object,
 84                       org.apache.commons.validator.ValidatorAction,
 85                       org.apache.commons.validator.Field,
 86                       org.apache.struts.action.ActionMessages,
 87                       org.apache.commons.validator.Validator,
 88                       javax.servlet.http.HttpServletRequest"
 89              depends=""
 90                  msg="errors.short"
 91       jsFunctionName="ShortValidations"/>
 92      <validator name="integer"
 93            classname="org.apache.struts.validator.FieldChecks"
 94               method="validateInteger"
 95         methodParams="java.lang.Object,
 96                       org.apache.commons.validator.ValidatorAction,
 97                       org.apache.commons.validator.Field,
 98                       org.apache.struts.action.ActionMessages,
 99                       org.apache.commons.validator.Validator,
100                       javax.servlet.http.HttpServletRequest"
101              depends=""
102                  msg="errors.integer"
103       jsFunctionName="IntegerValidations"/>
104      <validator name="long"
105            classname="org.apache.struts.validator.FieldChecks"
106               method="validateLong"
107         methodParams="java.lang.Object,
108                       org.apache.commons.validator.ValidatorAction,
109                       org.apache.commons.validator.Field,
110                       org.apache.struts.action.ActionMessages,
111                       org.apache.commons.validator.Validator,
112                       javax.servlet.http.HttpServletRequest"
113              depends=""
114                  msg="errors.long"/>
115      <validator name="float"
116            classname="org.apache.struts.validator.FieldChecks"
117               method="validateFloat"
118         methodParams="java.lang.Object,
119                       org.apache.commons.validator.ValidatorAction,
120                       org.apache.commons.validator.Field,
121                       org.apache.struts.action.ActionMessages,
122                       org.apache.commons.validator.Validator,
123                       javax.servlet.http.HttpServletRequest"
124              depends=""
125                  msg="errors.float"
126       jsFunctionName="FloatValidations"/>
127      <validator name="double"
128            classname="org.apache.struts.validator.FieldChecks"
129               method="validateDouble"
130         methodParams="java.lang.Object,
131                       org.apache.commons.validator.ValidatorAction,
132                       org.apache.commons.validator.Field,
133                       org.apache.struts.action.ActionMessages,
134                       org.apache.commons.validator.Validator,
135                       javax.servlet.http.HttpServletRequest"
136              depends=""
137                  msg="errors.double"/>
138      <validator name="date"
139            classname="org.apache.struts.validator.FieldChecks"
140               method="validateDate"
141         methodParams="java.lang.Object,
142                       org.apache.commons.validator.ValidatorAction,
143                       org.apache.commons.validator.Field,
144                       org.apache.struts.action.ActionMessages,
145                       org.apache.commons.validator.Validator,
146                       javax.servlet.http.HttpServletRequest"
147              depends=""
148                  msg="errors.date"
149       jsFunctionName="DateValidations"/>
150      <validator name="intRange"
151            classname="org.apache.struts.validator.FieldChecks"
152               method="validateIntRange"
153         methodParams="java.lang.Object,
154                       org.apache.commons.validator.ValidatorAction,
155                       org.apache.commons.validator.Field,
156                       org.apache.struts.action.ActionMessages,
157                       org.apache.commons.validator.Validator,
158                       javax.servlet.http.HttpServletRequest"
159              depends="integer"
160                  msg="errors.range"/>
161      <validator name="floatRange"
162            classname="org.apache.struts.validator.FieldChecks"
163               method="validateFloatRange"
164         methodParams="java.lang.Object,
165                       org.apache.commons.validator.ValidatorAction,
166                       org.apache.commons.validator.Field,
167                       org.apache.struts.action.ActionMessages,
168                       org.apache.commons.validator.Validator,
169                       javax.servlet.http.HttpServletRequest"
170              depends="float"
171                  msg="errors.range"/>
172      <validator name="doubleRange"
173            classname="org.apache.struts.validator.FieldChecks"
174               method="validateDoubleRange"
175         methodParams="java.lang.Object,
176                       org.apache.commons.validator.ValidatorAction,
177                       org.apache.commons.validator.Field,
178                       org.apache.struts.action.ActionMessages,
179                       org.apache.commons.validator.Validator,
180                       javax.servlet.http.HttpServletRequest"
181              depends="double"
182                  msg="errors.range"/>
183      <validator name="creditCard"
184            classname="org.apache.struts.validator.FieldChecks"
185               method="validateCreditCard"
186         methodParams="java.lang.Object,
187                       org.apache.commons.validator.ValidatorAction,
188                       org.apache.commons.validator.Field,
189                       org.apache.struts.action.ActionMessages,
190                       org.apache.commons.validator.Validator,
191                       javax.servlet.http.HttpServletRequest"
192              depends=""
193                  msg="errors.creditcard"/>
194      <validator name="email"
195            classname="org.apache.struts.validator.FieldChecks"
196               method="validateEmail"
197         methodParams="java.lang.Object,
198                       org.apache.commons.validator.ValidatorAction,
199                       org.apache.commons.validator.Field,
200                       org.apache.struts.action.ActionMessages,
201                       org.apache.commons.validator.Validator,
202                       javax.servlet.http.HttpServletRequest"
203              depends=""
204                  msg="errors.email"/>
205      <validator name="url"
206            classname="org.apache.struts.validator.FieldChecks"
207               method="validateUrl"
208         methodParams="java.lang.Object,
209                       org.apache.commons.validator.ValidatorAction,
210                       org.apache.commons.validator.Field,
211                       org.apache.struts.action.ActionMessages,
212                       org.apache.commons.validator.Validator,
213                       javax.servlet.http.HttpServletRequest"
214              depends=""
215                  msg="errors.url"/>
216     <!--
217       This simply allows struts to include the validateUtilities into a page, it should
218       not be used as a validation rule.
219     -->
220     <validator name="includeJavaScriptUtilities"
221            classname=""
222               method=""
223         methodParams=""<

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• 2006-03-07 17:53
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