<!--设置错误显示格式-->

<style type="text/css">
ul {
display: inline-block;
}
ul li{
display: inlin;
color: red;
}
</style>

。。。。。。

<form action="${pageContext.servletContext.contextPath }/User_register.do" method="post"><table align="center" border="1" cellpadding="5" cellspacing="0"><tr><th>用户名：</th><td><input type="text" name="user.uname"><s:fielderror fieldName="user.uname"></s:fielderror></td></tr><tr><th>年龄：</th><td><input type="text" name="user.uage"></td></tr><tr><th>性别：</th><td><input type="text" name="user.ugender"></td></tr><tr><th>生日：</th><td><input type="text" name="user.ubirthday"></td></tr><tr><td colspan="2" align="center"><input type="submit" value="提交" /> </td></tr></table></form>

<package name="Userpkg" extends="struts-default"><action name="User_*" class="com.huitong.action.UserAction" method="{1}"><result name="success">/index.jsp</result><result name="input">/register.jsp</result>  //如果验证有错误，会返回input，此处是让其跳转到注册页面</action></package>

    public String register(){System.out.println(user);return SUCCESS;}

    public void validateRegister() {if(user.getUname() == null || "".equals(user.getUname().trim())){super.addFieldError("username", "用户名不能为空！");return;}if(user.getUgender()==null || "".equals(user.getUgender().trim())){super.addFieldError("genderempty", "性别不能为空！");return;}        }

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC"-//Apache Struts//XWork Validator 1.0.3//EN""http://struts.apache.org/dtds/xwork-validator-1.0.3.dtd">
<validators><field name="user.uname"><field-validator type="requiredstring" ><message>用户名不能为空</message></field-validator></field></validators>