[Java知识库] springboot构建一个简单的拦截器

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[Java知识库]springboot构建一个简单的拦截器

1.构建实体类(使用了一个lombok插件)

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private Integer id;
    private String username;
    private String password;
}

2.编写前端页面

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>登录</title>
</head>
<body>
<form th:action="@{/doLogin}" method="post">
    <h1>登录</h1>
    <p style="color: red" th:text="${msg}"></p>
    <input type="text" th:name="username"><br>
    <input type="password" th:name="password"><br>
    <input type="submit" th:value="登录">
</form>
</body>
</html>

success.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>登陆成功</h1>
<br>
<a th:href="@{/stu/logOut}">退出</a>
</body>
</html>

3.构建controller

@Controller
public class StudentController {

    @RequestMapping("/doLogin")
    public String doLogin(String username, String password, HttpSession session, Model model){
        User user = new User(1, "admin", "123456"); //应该从数据库中比对后查询出
        if (username.equals(user.getUsername()) && password.equals(user.getPassword())){
            session.setAttribute("student",user); //如果用户名与密码输入正确，就存入session
            return "redirect:/stu/toSuccess";
        }else {
            model.addAttribute("msg","用户名或密码错误");
            return "login"; //如果错误，重回登录页面
        }

    }

    @RequestMapping("/stu/toSuccess")
    public String toSuccess(){  //登录成功后前往页面
        return "success";
    }

    @RequestMapping("/stu/logOut")
    public String logOut(HttpSession session){
        session.removeAttribute("student");  //退出清除session
        return "redirect:/toLogin";
    }

}

4.自定义config

MyMvcConfig.java(拦截器)

//扩展springMv
@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("login");//访问/路径前往login页面
        registry.addViewController("/toLogin").setViewName("login");
    }

    //注册拦截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/stu/**") //拦截stu下的所有请求
                .excludePathPatterns("/index.html","/","/user/login","/css/**","/js/**","/img/**");//静态资源不拦截
    }
}

LoginHandlerInterceptor.java(使拦截器生效)

public class LoginHandlerInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Object student = request.getSession().getAttribute("student"); //获取student的session

        if (student==null){    //session为空则未登录，拒绝请求
            request.setAttribute("msg","没有权限，请先登录");
            request.getRequestDispatcher("/").forward(request,response);
            return false;
        }else {
            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 {

    }
}

依赖

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>