数据校验一（利用Spring自带的validation校验框架）

实现了Validator接口，前端页面使用<form:errors>标签显示属性的错误信息

1.javaBean

package com.bean;

public class User {
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;
}

}

2.前端登陆页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib uri= "http://www.springframework.org/tags/form" prefix="form" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>测试Validator接口验证</title>
</head>
<body>
<h3>登录页面</h3>

<form:form modelAttribute="user" method="post" action="tologin" >
<table>
  <tr>
   <td>登录名:</td>
   <td><input type="text" name="username" id="username" /></td>
   
   <td><form:errors path="username" cssStyle="color:red"/></td>
  </tr>
  <tr>
   <td>密码:</td>
   <td><form:input path="password"/></td>
   
   <td><form:errors path="password" cssStyle= "color:red"/></td>
  </tr>
  <tr>
   <td><input type="submit" value="提交"/></td>
  </tr>
</table>
</form:form>
</body>
</html>

3.MyValidator类，实现了Validator接口

package com.validator;

import org.springframework.stereotype.Component;
import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;

import com.bean.User;

@Component("validator")
public class MyValidator implements Validator {

@Override
public boolean supports(Class<?> clazz) {
// TODO Auto-generated method stub
return User.class.isAssignableFrom(clazz);
}

@Override
public void validate(Object target, Errors errors) {
  // TODO Auto-generated method stub
  User user = (User)target;
  ValidationUtils.rejectIfEmpty(errors, "username", "U404", "用户名不能为空");
  ValidationUtils.rejectIfEmpty(errors, "password", null, "密码不能为空");

  if(user.getUsername().length() > 10){
   errors.rejectValue("username", "U405", "用户名长度不能超过10个字符");
  }

  if(user.getPassword().length() < 6){
   errors.rejectValue("password", null, "密码长度不能小于6个字符");
  }
}

}

4.Controller类

package com.controller;

import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

import com.bean.User;
import com.validator.MyValidator;

@Controller
public class UserController {
@Autowired
@Resource
private MyValidator validator;
@RequestMapping("/{login}")
public String login(@PathVariable String login, ModelMap mm){
  mm.addAttribute("user", new User());
  return login;
}

@RequestMapping("/tologin")
//在需要校验的属性前面加@Validated
//BindingResult属性必须要放在@Validated注解属性的后面，否则spring会在校验不通过时直接抛出异常
public String tologin(@Validated User user, BindingResult result){
  if(result.hasErrors()){
   return "login";
  }

  return "success";
}
@InitBinder
public void initBinder(WebDataBinder binder){
  binder.setValidator(validator);
}
/*@RequestMapping("/tologin")
//在需要校验的属性前面加@Validated
//Errors属性必须要放在@Validated注解属性的后面
public String tologin(@Validated User user, Errors errors){
  validator.validate(user, errors);
  if(errors.hasErrors()){
   return "login";
  }
  return "success";
}*/

}

上面两种@RequestMapping("/tologin")映射的作用效果一样

5.配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.3.xsd">

    
    <context:component-scan base-package="com.controller"/>
    <context:component-scan base-package="com.validator"/>
    <mvc:annotation-driven />

    
     <bean id="viewResolver"
          class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        
        <property name="prefix">
            <value>/WEB-INF/jsp/</value>
        </property>
        
        <property name="suffix">
            <value>.jsp</value>
        </property>
    </bean>

</beans>

数据校验一（利用Spring自带的validation校验框架）

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