struts校验框架提供两种校验：客户端校验和服务端校验。它们都是主要检查浏览器输入数据是否合法的校验器。
- 服务端校验
服务端校验是在服务器上检查输入数据，它的实现方法是重写validate()方法。如果想对特定方法进行校验，须实现validate方法名()（方法名首字母大写）。
import java.util.Map; import javax.servlet.http.HttpServletRequest; import org.apache.struts2.ServletActionContext; import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport; public class LoginAction extends ActionSupport
{ /**
*
*/
private static final long serialVersionUID = 1L;
private String username ;
private String password; public LoginAction(){
System.out.println("constructor called!");
} public String getPassword() {
return password;
} public void setPassword(String password) {
this.password = password;
} public String getUsername() {
return username;
} public void setUsername(String username) {
this.username = username;
}
@Override
public String execute() throws Exception { if(username.equals(""))
return ERROR;
else{ context.getSession().put("username", username); return SUCCESS;
} }
public void validateExecute(){
System.out.println("validateExecute called!"); } public void validate(){
System.out.println("validate called!");
if(getUsername()==null || getUsername().trim().equals(""))
this.addFieldError("username", "必须输入用户名");
if(getPassword()==null || getUsername().trim().equals(""))
this.addFieldError("password", "必须输入密码"); } }
如执行结果，校验是先执行针对方法的校验，最后执行总的校验，所以在实现的过程中需要小心校验的覆盖问题。
- 客户端校验
这种校验的格式比较繁杂，它是在浏览器中执行的。实现struts2的客户端校验，首先需要写一个Action，配置好Action的input页面，再写一个ActionName-validate.xml文件，并且要把这个xml文件放在相应action的同一包下。
Action：
import com.opensymphony.xwork2.ActionSupport;
public class RegisterAction extends ActionSupport{
private String username;
private String password;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String execute(){
return SUCCESS;
}
}
RegisterAction-validate.xml:
<?xml version="1.0" encoding="utf-8"?>
<!-- 指定校验配置文件的DTD信息 -->
<!DOCTYPE validators PUBLIC
"-//Apache Struts//XWork Validator 1.0.3//EN"
"http://struts.apache.org/dtds/xwork-validator-1.0.3.dtd">
<!-- 校验文件的根元素 -->
<validators> <field name="username">
<field-validator type="requiredstring">
<message>users should be not blank!</message>
</field-validator> <field-validator type="stringlength">
<param name="minLength">6</param>
<param name="maxLength">10</param>
<message>users should be between ${minLength} and ${maxLength}</message>
</field-validator>
</field>
<field name="password" >
<field-validator type="requiredstring" short-circuit="true">
<param name="trim">true</param>
<message>should input password</message>
</field-validator> </field>
</validators>
然后在页面表格上设置校验为true,struts的校验框架需要用s标签库。
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@taglib prefix="s" uri="/struts-tags"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Login2</title>
</head>
<body>
<s:form action="RegisterAction.action" validate="true">
<s:textfield name="username" label="用户名"></s:textfield>
<s:password name="password" label="密码"></s:password>
<s:submit value="注册"></s:submit>
</s:form>
</body>
</html>
验证失败之后会返回input字符串
最后补充一下default.xml的校验器
<validators>
<validator name="required" class="com.opensymphony.xwork2.validator.validators.RequiredFieldValidator"/>
<validator name="requiredstring" class="com.opensymphony.xwork2.validator.validators.RequiredStringValidator"/>
<validator name="int" class="com.opensymphony.xwork2.validator.validators.IntRangeFieldValidator"/>
<validator name="long" class="com.opensymphony.xwork2.validator.validators.LongRangeFieldValidator"/>
<validator name="short" class="com.opensymphony.xwork2.validator.validators.ShortRangeFieldValidator"/>
<validator name="double" class="com.opensymphony.xwork2.validator.validators.DoubleRangeFieldValidator"/>
<validator name="date" class="com.opensymphony.xwork2.validator.validators.DateRangeFieldValidator"/>
<validator name="expression" class="com.opensymphony.xwork2.validator.validators.ExpressionValidator"/>
<validator name="fieldexpression" class="com.opensymphony.xwork2.validator.validators.FieldExpressionValidator"/>
<validator name="email" class="com.opensymphony.xwork2.validator.validators.EmailValidator"/>
<validator name="url" class="com.opensymphony.xwork2.validator.validators.URLValidator"/>
<validator name="visitor" class="com.opensymphony.xwork2.validator.validators.VisitorFieldValidator"/>
<validator name="conversion" class="com.opensymphony.xwork2.validator.validators.ConversionErrorFieldValidator"/>
<validator name="stringlength" class="com.opensymphony.xwork2.validator.validators.StringLengthFieldValidator"/>
<validator name="regex" class="com.opensymphony.xwork2.validator.validators.RegexFieldValidator"/>
<validator name="conditionalvisitor" class="com.opensymphony.xwork2.validator.validators.ConditionalVisitorFieldValidator"/>
</validators>
以及字段的意思：
（1）field：需要校验的字段，name属性值需要和action中的字段一致；
（2）field-validator：校验器，type属性值为struts2框架提供的校验器。路径为：项目导入的jar包xwork-core-2.3.16.3.jar/com.opensymphony.xwork2.validator.validators/default.xml
（3）接着param是为type指定的校验器提供参数值，因为一个校验器对应一个java类，可以通过param标签为该类中的字段指定值。这里<param name="trim">true</param>意思是设置requiredstring校验器所引用的类com.opensymphony.xwork2.validator.validators.RequiredStringValidator中的字段trim的值为true，意思是对username属性值作去前后空格处理。
（4）<message>用于发送错误信息
（5）此外xml文件的模版可以在struts2官方提供的框架压缩包中找到，路径为：struts-2.3.16.3\src\xwork-core\src\main\resources