2.校验文件可以使用国际化提示信息，只需要在对应的.properties文件中添加好键值对，然后在验证文件中使用即可。比如，提示信息message标签，可以这么写<message key="name.regex"/>,其中name.regex为国际化信息文件中的内容。
3.校验器可以有两种风格，上面转载的是字段（field）校验器风格，还有非字段校验器风格，如下所示（当然，最外层也是<validators>标签
<validator type="expression>
<param name="expression">foo gt bar</param>
<message>foo must be great than bar.</message>
</validator>
<validator type="required">
<param name="fieldName">bar</param>
<message>You must enter a value for bar.</message>
</validator>
<validator type="校验器名">
<param name="fieldName">需要被校验的字段</param>
<!-- 可以有0个或多个 -->
<param name="参数名">参数值</param>
<message>You must enter a value for bar.</message>
</validator>
4.短路校验器：默认都是短路的，如果没有短路，在validator标签（非字段风格）或者field-validator标签（字段风格）增加属性short-circuit="true"即可
5.很多验证标签的type已经改了，对应的param里面的name属性也改了-----针对最新版的struts。建议详细阅读struts的validation.html,在docs/docs下。
6.最新的内建校验器：
（1）conversion校验器
<validators>
...
<field name="myIntegerField">
<field-validator type="conversion">
<param name="repopulateField">true</param>
<message>Conversion Error (Integer Wanted)</message>
</field-validator>
</field>
...
</validators>
<pre>
<!-- Plain Validator Syntax -->
<validator type="conversion">
<param name="fieldName">myField</param>
<message>Conversion Error Occurred</message>
</validator>
<!-- Field Validator Syntax -->
<field name="myField">
<field-validator type="conversion">
<message>Conversion Error Occurred</message>
</field-validator>
</field>
</pre>
（2）date 校验器
<validators>
<!-- Plain Validator syntax -->
<validator type="date">
<param name="fieldName">birthday</param>
<param name="min">01/01/1990</param>
<param name="max">01/01/2000</param>
<message>Birthday must be within ${min} and ${max}</message>
</validator>
<!-- Field Validator Syntax -->
<field name="birthday">
<field-validator type="date">
<param name="min">01/01/1990</param>
<param name="max">01/01/2000</param>
<message>Birthday must be within ${min} and ${max}</message>
</field>
</field>
<!-- Field Validator Syntax with expression -->
<field name="birthday">
<field-validator type="date">
<param name="minExpression">${minValue}</param> <!-- will be evaluated as: Date getMinValue() -->
<param name="maxExpression">${maxValue}</param> <!-- will be evaluated as: Date getMaxValue() -->
<message>Age needs to be between ${min} and ${max}</message>
</field-validator>
</field>
</validators>
（3）double 验证器
<validators>
<!-- Plain Validator Syntax -->
<validator type="double">
<param name="fieldName">percentage</param>
<param name="minInclusive">20.1</param>
<param name="maxInclusive">50.1</param>
<message>Age needs to be between ${minInclusive} and ${maxInclusive} (inclusive)</message>
</validator>
<!-- Field Validator Syntax -->
<field name="percentage">
<field-validator type="double">
<param name="minExclusive">0.123</param>
<param name="maxExclusive">99.98</param>
<message>Percentage needs to be between ${minExclusive} and ${maxExclusive} (exclusive)</message>
</field-validator>
</field>
<!-- Field Validator Syntax with expression -->
<field name="percentage">
<field-validator type="double">
<param name="minExclusiveExpression">${minExclusiveValue}</param> <!-- will be evaluated as: Double getMinExclusiveValue() -->
<param name="maxExclusiveExpression">${maxExclusiveValue}</param> <!-- will be evaluated as: Double getMaxExclusiveValue() -->
<message>Percentage needs to be between ${minExclusive} and ${maxExclusive} (exclusive)</message>
</field-validator>
</field>
</validators>
（4）email验证器
<!-- Plain Validator Syntax -->
<validators>
<validator type="email">
<param name="fieldName">myEmail</param>
<message>Must provide a valid email</message>
</validator>
</validators>
<!-- Field Validator Syntax -->
<field name="myEmail">
<field-validator type="email">
<message>Must provide a valid email</message>
</field-validator>
</field>
<!-- Field Validator Syntax with expressions -->
<!-- Only available when used with xml based configuration, if you want to have the same
flexibility with annotations use @RegexFieldValidator instead -->
<field name="myEmail">
<field-validator type="email">
<param name="regexExpression">${emailPattern}</param> <!-- will be evaluated as: String getEmailPattern() -->
<param name="caseSensitiveExpression">${emailCaseSensitive}</param> <!-- will be evaluated as: boolean getEmailCaseSensitive() -->
<param name="trimExpression">${trimEmail}</param> <!-- will be evaluated as: boolean getTrimEmail() -->
<message>Must provide a valid email</message>
</field-validator>
</field>
（5）expression验证器
<validators>
<validator type="expression">
<param name="expression"> .... </param>
<message>Failed to meet Ognl Expression .... </message>
</validator>
</validators>
（6）fieldexpression 验证器
<!-- Plain Validator Syntax -->
<validators>
<!-- Plain Validator Syntax -->
<validator type="fieldexpression">
<param name="fieldName">myField</param>
<param name="expression"><![CDATA[#myCreditLimit > #myGirfriendCreditLimit]]></param>
<message>My credit limit should be MORE than my girlfriend</message>
<validator>
<!-- Field Validator Syntax -->
<field name="myField">
<field-validator type="fieldexpression">
<param name="expression"><![CDATA[#myCreditLimit > #myGirfriendCreditLimit]]></param>
<message>My credit limit should be MORE than my girlfriend</message>
</field-validator>
</field>
</vaidators>
（7）int 验证器
<validators>
<!-- Plain Validator Syntax -->
<validator type="int">
<param name="fieldName">age</param>
<param name="min">20</param>
<param name="max">50</param>
<message>Age needs to be between ${min} and ${max}</message>
</validator>
<!-- Field Validator Syntax -->
<field name="age">
<field-validator type="int">
<param name="min">20</param>
<param name="max">50</param>
<message>Age needs to be between ${min} and ${max}</message>
</field-validator>
</field>
<!-- Field Validator Syntax with expression -->
<field name="age">
<field-validator type="int">
<param name="minExpression">${minValue}</param> <!-- will be evaluated as: Integer getMinValue() -->
<param name="maxExpression">${maxValue}</param> <!-- will be evaluated as: Integer getMaxValue() -->
<message>Age needs to be between ${min} and ${max}</message>
</field-validator>
</field>
</validators>
（8）regex验证器
<validators>
<!-- Plain Validator Syntax -->
<validator type="regex">
<param name="fieldName">myStrangePostcode</param>
<param name="regex"><![CDATA[([aAbBcCdD][123][eEfFgG][456])]]></param>
</validator>
<!-- Field Validator Syntax -->
<field name="myStrangePostcode">
<field-validator type="regex">
<param name="regex"><![CDATA[([aAbBcCdD][123][eEfFgG][456])]]></param>
</field-validator>
</field>
<!-- Field Validator Syntax with expressions -->
<field name="myStrangePostcode">
<field-validator type="regex">
<param name="regexExpression">${regexValue}</param> <!-- will be evaluated as: String getRegexValue() -->
<param name="caseSensitiveExpression">${caseSensitiveValue}</param> <!-- will be evaluated as: boolean getCaseSensitiveValue() -->
<param name="trimExpression">${trimValue}</param> <!-- will be evaluated as: boolean getTrimValue() -->
</field-validator>
</field>
</validators>
（9）required验证器
<validators>
<!-- Plain Validator Syntax -->
<validator type="required">
<param name="fieldName">username</param>
<message>username must not be null</message>
</validator>
<!-- Field Validator Syntax -->
<field name="username">
<field-validator type="required">
<message>username must notbe null</message>
</field-validator>
</field>
</validators>
（10）requiredstring 验证器
<validators>
<!-- Plain-Validator Syntax -->
<validator type="requiredstring">
<param name="fieldName">username</param>
<param name="trim">true</param>
<message>username is required</message>
</validator>
<!-- Field-Validator Syntax -->
<field name="username">
<field-validator type="requiredstring">
<param name="trim">true</param>
<message>username is required</message>
</field-validator>
</field>
<!-- Field-Validator Syntax with expression -->
<field name="username">
<field-validator type="requiredstring">
<param name="trimExpression">${trimValue}</param> <!-- will be evaluated as: boolean getTrimValue() -->
<message>username is required</message>
</field-validator>
</field>
</validators>
（11）short验证器
<validators>
<!-- Plain Validator Syntax -->
<validator type="short">
<param name="fieldName">age</param>
<param name="min">20</param>
<param name="max">50</param>
<message>Age needs to be between ${min} and ${max}</message>
</validator>
<!-- Field Validator Syntax -->
<field name="age">
<field-validator type="short">
<param name="min">20</param>
<param name="max">50</param>
<message>Age needs to be between ${min} and ${max}</message>
</field-validator>
</field>
<!-- Field Validator Syntax with expression -->
<field name="age">
<field-validator type="short">
<param name="minExpression">${minValue}</param> <!-- will be evaluated as: Short getMinValue() -->
<param name="maxExpression">${maxValue}</param> <!-- will be evaluated as: Short getMaxValue() -->
<message>Age needs to be between ${min} and ${max}</message>
</field-validator>
</field>
</validators>
（12）stringlength 验证器
<validators>
<!-- Plain Validator Syntax -->
<validator type="stringlength">
<param name="fieldName">myPurchaseCode</param>
<param name="minLength">10</param>
<param name="maxLength">10</param>
<param name="trim">true</param>
<message>Your purchase code needs to be 10 characters long</message>
</validator>
<!-- Field Validator Syntax -->
<field name="myPurchaseCode">
<field-validator type="stringlength">
<param name="minLength">10</param>
<param name="maxLength">10</param>
<param name="trim">true</param>
<message>Your purchase code needs to be 10 characters long</message>
</field-validator>
</field>
<!-- Field Validator Syntax with expression -->
<field name="myPurchaseCode">
<field-validator type="stringlength">
<param name="minLengthExpression">${minLengthValue}</param> <!-- will be evaluated as: Integer getMinLengthValue() -->
<param name="maxLengthExpression">${maxLengthValue}</param> <!-- will be evaluated as: Integer getMaxLengthValue() -->
<param name="trimExpression">${trimValue}</param> <!-- will be evaluated as: boolean getTrimValue() -->
<message>Your purchase code needs to be 10 characters long</message>
</field-validator>
</field>
</validators>
（13）url验证器
<!-- Plain Validator Syntax -->
<validator type="url">
<param name="fieldName">myHomePage</param>
<message>Invalid homepage url</message>
</validator>
<!-- Field Validator Syntax -->
<field name="myHomepage">
<field-validator type="url">
<message>Invalid homepage url</message>
</field-validator>
</field>
</validators>
（14）visitor验证器
<validators>
<!-- Plain Validator Syntax -->
<validator type="visitor">
<param name="fieldName">user</param>
<param name="context">myContext</param>
<param name="appendPrefix">true</param>
</validator>
<!-- Field Validator Syntax -->
<field name="user">
<field-validator type="visitor">
<param name="context">myContext</param>
<param name="appendPrefix">true</param>
</field-validator>
</field>
</validators>
（15）conditionalvisitor验证器
<field name="colleaguePosition">
<field-validator type="conditionalvisitor">
<param name="expression">reason == 'colleague' and colleaguePositionID == 'OTHER'</param>
<message>You must select reason Colleague and position Other</message>
</field-validator>
</field>
