springboot_简单用户登录和拦截器

1、为登录页面的form表单,添加th:action进入controller

<form class="form-signin" th:action="@{/user/login}">

2、input标签添加“name”属性

<input type="text" name="username" class="form-control" th:placeholder="#{login.username}" required="" autofocus="">
<input type="password" name="password" class="form-control" th:placeholder="#{login.password}" required="">

3、进入controller实现具体的业务代码

新建controller

@Controller
public class LoginController {
    @RequestMapping("/user/login")
    public String login(
            @RequestParam("username")String username,
            @RequestParam("password")String password,
            Model model,
            HttpSession session){
        //具体业务：
        if (!StringUtils.isEmpty(username) && "123456".equals(password)){
            System.out.println(username+":"+password);
            session.setAttribute("loginUser",username);
            //重定向
            return "redirect:/main.html";
        }else {
            model.addAttribute("msg","用户名或密码错误");
            return "index";
        }
    }
}

如果密码错误页面显示错误信息：

<!--th:if thymeleaf模板语法，进行条件判断-->
<p style="color: red" th:text="${msg}" th:if="${not #strings.isEmpty(msg)}"></p>

img.png

• @RequestParam：获取登录页面的username和password参数
• Model：进行数据的回显
• HttpSession：用于设置session，用于后续拦截器的判断条件

4、在MyMvcConfig进行地址映射

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
        registry.addViewController("/index.html").setViewName("index");
        registry.addViewController("/main.html").setViewName("dashboard");
    }
}

映射前uri：
http://localhost:8080/user/login?username=123&password=123456
映射后uri:
http://localhost:8080/main.html

5、拦截器设置

创建LoginHandlerInterceptor实现HandlerInterceptor接口
重写方法：

• public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {}
• public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {}
• public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {}

public class LoginHandlerInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //登录成功之后。应该有用户的session
        Object loginUser = request.getSession().getAttribute("loginUser");
        //没有登录
        if (loginUser==null){
            request.setAttribute("msg","请先登录");
            //返回主页，转发request和response
            request.getRequestDispatcher("/index.html").forward(request,response);
            return false;
        }else {
            return true;
        }
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

6、在MyMvcConfig中配置拦截器

public class MyMvcConfig implements WebMvcConfigurer {

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
        registry.addViewController("/index.html").setViewName("index");
        registry.addViewController("/main.html").setViewName("dashboard");
    }

    @Bean
    public LocaleResolver localeResolver(){
        return new MyLocaleResolver();
    }

    //配置拦截器
    public void addInterceptors(InterceptorRegistry registry){
        registry.addInterceptor(new LoginHandlerInterceptor())
                .addPathPatterns("/**")
                .excludePathPatterns("/index.html",
                        "/",
                        "/user/login",
                        "/css/**",
                        "/js/**",
                        "/img/**");
    }
}

如果没有登录提示用户登录
img_1.png