做学生登录信息必填项验证。

student信息有：id,姓名，年龄

Student.java

public class Student {		private Integer id;	private Integer age;	private String name;		public Integer getId() {		return id;	}	public void setId(Integer id) {		this.id = id;	}		public Integer getAge() {		return age;	}	public void setAge(Integer age) {		this.age = age;	}		public String getName() {		return name;	}	public void setName(String name) {		this.name = name;	}		}

　　StudentValidator.java数据验证代码

import org.springframework.stereotype.Service;import org.springframework.validation.Errors;import org.springframework.validation.ValidationUtils;import org.springframework.validation.Validator;@Servicepublic class StudentValidator implements Validator {		public boolean supports(Class
      clazz){		return Student.class.isAssignableFrom(clazz);	}	public void validate(Object target, Errors errors) {        	      ValidationUtils.rejectIfEmptyOrWhitespace(errors, "name", "required.name","Field name is required.");	}}

　　注意：StudentValidator 需要加@Service注解，否则自动装载会报错，找不到bean

自动注入的时候，找不到对应的bean

原因是：对应要注入的实现类没有 加注解，如dao层 @Repository  如service层  @Service

 

StudentController.java

import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Qualifier;import org.springframework.stereotype.Controller;import org.springframework.web.servlet.ModelAndView;import org.springframework.web.bind.WebDataBinder;import org.springframework.web.bind.annotation.InitBinder;import org.springframework.web.bind.annotation.ModelAttribute;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.ui.Model;import org.springframework.validation.BindingResult;import org.springframework.validation.Validator;import org.springframework.validation.annotation.Validated;@Controllerpublic class StudentController {		@Autowired		@Qualifier("studentValidator")		private Validator validator;					@InitBinder		private void initBinder(WebDataBinder binder) {		      binder.setValidator(validator);		}			//前端from数据引用:commandName		 @ModelAttribute("student")		   public Student createStudentModel() {    		      return new Student();		   }				@RequestMapping(value = "/student", method = RequestMethod.GET)	   public ModelAndView student() {	      return new ModelAndView("student", "command", new Student());	   }	  	   @RequestMapping(value = "/addStudent", method = RequestMethod.POST)	   public String addStudent(@ModelAttribute("student") @Validated Student student, 	      BindingResult bindingResult, Model model) {	      if (bindingResult.hasErrors()) {	         return "student";	      }	      model.addAttribute("name", student.getName());	      model.addAttribute("age", student.getAge());	      model.addAttribute("id", student.getId());	      return "student_result";	   }			}

　　下面来看看jsp代码

student.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%><%@ taglib uri="http://www.springframework.org/tags/form" prefix="form"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><%@ page isELIgnored="false" %>
          
学生信息
    
              
               
       
                    
         
                          
           
            姓名：
           
                          
           
                          
           
                     
                     
                          
           
            年龄：
           
                          
           
                     
                     
                          
           
            编号：
           
                          
           
                     
                     
                          
                     
                
       
    
      

　　

这一块的代码：

<form:form method="POST" action="/hello/addStudent" commandName="student">，其中commandName中的student是,studentController中的createStudentModel的定义.

这一块的代码：<form:errors path="*" cssClass="errorStyle" element="div" />，cssClass为样式代码,element元素为div.

 

student_result.jsp

<%@ page contentType="text/html; charset=UTF-8" %><%@taglib uri="http://www.springframework.org/tags/form" prefix="form"%><%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%><%@ page isELIgnored="false" %>
      
提交的学生信息
      
	       
        
		         
名称:
		         
${name}
	        
	        
		         
年龄:
		         
${age}
	        
	        
		         
编号:
		         
${id}