<!-- JSR303 -->
<hibernate.validator.version>6.0.7.Final</hibernate.validator.version>
 
<!-- JSR303 -->
<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-validator</artifactId>
    <version>${hibernate.validator.version}</version>
</dependency>

在实体类相对应的属性中增加注解用来指定校验

 @NotNull(message = "班级编号不能为空")
//    @Size(max = 100,min = 10,message = "大小必须在10至100之间")
    protected Integer book_id;

    @NotBlank(message = "班级名不能为空")
    protected String book_name;

    @NotBlank(message = "班级教员老师不能为空")
    protected Float price;

    private String image="暂无图片";

增加以下方法

@RequestMapping("/valiAdd")
    public String valiAdd(@Validated Bookxx bookxx,
                          BindingResult result,
                          HttpServletRequest req){
//        如果服务端验证不通过，有错误
        if(result.hasErrors()){
//            服务端验证了实体类的多个属性，多个属性都没有验证通过
            List<FieldError> fieldErrors = result.getFieldErrors();
            Map<String,Object> map = new HashMap<>();
            for (FieldError fieldError : fieldErrors) {
//                将多个属性的验证失败信息输送到控制台
                System.out.println(fieldError.getField() + ":" + fieldError.getDefaultMessage());
                map.put(fieldError.getField(),fieldError.getDefaultMessage());
            }
            req.setAttribute("errorMap",map);
        }else {
            this.bookxxBiz.insertSelective(bookxx);
            return "redirect:list";
        }
        return "clz/edit";
    }

在我们的编辑页面修改一下代码

<h1>编辑界面</h1>
<form action="${pageContext.request.contextPath }/clz/${empty book?'valiAdd' : 'edit'}" method="post">
    书籍编号:<input type="text" name="book_id" value="${book.book_id }"><span style="color: red;">${errorMap.book_id}</span><br>
    书籍名字:<input type="text" name="book_name" value="${book.book_name }"><span style="color: red;">${errorMap.book_name}</span><br>
    价格:<input type="text" name="price" value="${book.price }"><span style="color: red;">${errorMap.price}</span><br>
    <input type="submit">
</form>

测试

拦截器是什么

拦截器的工作原理

拦截器的作用

拦截器的使用

创建一个名为 Interceptor 的包，存放创建自定义拦截器 再创建一个创建自定义拦截器，名为 : OneInterceptor

package com.xiaoxu.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class OneInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("【OneInterceptor】：preHandle...");

        return true ;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("【OneInterceptor】：postHandle...");

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("【OneInterceptor】：afterCompletion...");
    }
}

配置自定义拦截器

 <mvc:interceptors>
        <bean class="com.xiaoxu.interceptor.OneInterceptor"></bean>
    </mvc:interceptors>

在 Interceptor 的包里，创建一个拦截器 TwoInterceptor。

package com.xiaoxu.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class TwoInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("【TwoInterceptor】：preHandle...");

        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("【TwoInterceptor】：postHandle...");

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("【TwoInterceptor】：afterCompletion...");
    }
}

创建一个名为 : LoginInterceptor 的拦截器

package com.xiaoxu.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("【implements】：preHandle...");
        StringBuffer url = request.getRequestURL();
        if (url.indexOf("/login") > 0 || url.indexOf("/logout") > 0){
            //        如果是 登录、退出 中的一种
            return true;
        }
//            代表不是登录，也不是退出
//            除了登录、退出，其他操作都需要判断是否 session 登录成功过
        String uname = (String) request.getSession().getAttribute("uname");
        if (uname == null || "".equals(uname)){
            response.sendRedirect("/page/login");
            return false;
        }
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

创建一个名为 : LoginController 的控制器

package com.xiaoxu.web;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

/**
 * @author小徐
 * @site www.veryedu.cn
 * @company xu集团
 * @create 2023-09-12 13:27
 */
@Controller
public class LoginController {
    @RequestMapping("/login")
    public String login(HttpServletRequest req){
        String uname = req.getParameter("uname");
        HttpSession session = req.getSession();
        if ("zs".equals(uname)){
            session.setAttribute("uname",uname);
        }
        return "redirect:/clz/list";
    }

    @RequestMapping("/logout")
    public String logout(HttpServletRequest req){
        req.getSession().invalidate();
        return "redirect:/clz/list";
    }
}

创建一个 login.jsp 的显示页面，进行测试效果

<%--
  Created by IntelliJ IDEA.
  User: 86155
  Date: 2023/9/12
  Time: 13:26
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>

<body>
<h1>登录</h1>
<form action="/login" method="post">
    用户:<input name="uname">
    <input type="submit">

</form>
</body>
</html>

测试