springboot开发之实现登录功能

接上一节。

开发期间更改模板后使其实时生效，需要进行两步：

在主配置文件中禁用模板缓存：spring.thymeleaf.cache=false。
修改完模板后按ctrl+f9进行重新编译。

1、首先是login.html：指定我们表单发送的请求

<!DOCTYPE html>
<html lang="en"  xmlns:th="http://www.thymeleaf.org">
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
        <meta name="description" content="">
        <meta name="author" content="">
        <title>Signin Template for Bootstrap</title>
        <!-- Bootstrap core CSS -->
        <link href="asserts/css/bootstrap.min.css" th:href="@{/webjars/bootstrap/4.1.2/css/bootstrap.css}" rel="stylesheet">
        <!-- Custom styles for this template -->
        <link href="asserts/css/signin.css" th:href="@{/asserts/css/signin.css}" rel="stylesheet">
    </head>
    <body class="text-center">
        <form class="form-signin" action="/" th:action="@{/user/login}" method="post">
            <img class="mb-4" th:src="@{/asserts/img/bootstrap-solid.svg}" src="asserts/img/bootstrap-solid.svg" alt="" width="72" height="72">
            <h1 class="h3 mb-3 font-weight-normal" th:text="#{login.tip}" >Please sign in</h1>
            <!--判断-->
            <p style="color: red" th:text="${msg}" th:if="${not #strings.isEmpty(msg)}"></p>
            <label class="sr-only" th:text="#{login.username}">Username</label>
            <input type="text"  name="username" class="form-control" placeholder="Username" th:placeholder="#{login.username}" required="" autofocus="">
            <label class="sr-only" th:text="#{login.password}">Password</label>
            <input type="password" name="password" class="form-control" placeholder="Password" th:placeholder="#{login.password}" required="">
            <div class="checkbox mb-3">
                <label>
                      <input type="checkbox" value="remember-me"/> [[#{login.remember}]]
                </label>
            </div>
            <button class="btn btn-lg btn-primary btn-block" type="submit" th:text="#{login.btn}" >Sign in</button>
            <p class="mt-5 mb-3 text-muted">© 2017-2018</p>
            <a class="btn btn-sm" th:href="@{/login.html(l='zh_CN')}">中文</a>
            <a class="btn btn-sm" th:href="@{/login.html(l='en_US')}">English</a>
        </form>
    </body>

</html>

2、在com.gong.springbootcurd.controller下新建LoginController.java

package com.gong.springbootcurd.controller;

import org.springframework.stereotype.Controller;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.*;

import javax.servlet.http.HttpSession;
import java.util.Map;

@Controller
public class LoginController {

//    @DeleteMapping
//    @PutMapping
//    @GetMapping

    //@RequestMapping(value = "/user/login",method = RequestMethod.POST)
    @PostMapping(value = "/user/login")
    public String login(@RequestParam("username") String username,
                        @RequestParam("password") String password,
                        Map<String,Object> map, HttpSession session){
        if("admin".equals(username) && "123456".equals(password)){
            //登陆成功，防止表单重复提交，可以重定向到主页
            session.setAttribute("loginUser",username);
            return "redirect:/main.html";
        }else{
            //登陆失败
            map.put("msg","用户或名密码错误");
            return  "login";
        }

    }
}

说明：这里我们可以使用PostMapping发送Post请求，不必向原来的springmvc那样麻烦。直接模拟账号和密码，如果是admin+123456，则将用户名存放到session中，为了避免重复提交，重定向到/main.html。如果登录失败，则返回错误信息“用户名或密码错误”到登录界面。

3、配置/main.html跳转到/templates/dashboard.html同时，为了避免没有登录而直接发送请求进入该页面，需要配置一个登录拦截器。

在com.gong.springbootcurd.component下新建LoginHandlerInceptor.java

package com.gong.springbootcurd.component;

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

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

/**
 * 登陆检查，
 */
public class LoginHandlerInterceptor implements HandlerInterceptor {
    //目标方法执行之前
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Object user = request.getSession().getAttribute("loginUser");
        if(user == null){
            //未登陆，返回登陆页面
            request.setAttribute("msg","没有权限请先登陆");
            request.getRequestDispatcher("/login.html").forward(request,response);
            return false;
        }else{
            //已登陆，放行请求
            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 {

    }
}

从session中获取用户名，如果有，则放行，如果没有，将错误信息传给login.html。

MyMvcConfig.java

package com.gong.springbootcurd.config;

import com.gong.springbootcurd.component.LoginHandlerInterceptor;
import com.gong.springbootcurd.component.MyLocaleResolver;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

//@EnableWebMvc 接管springmvc
@Configuration
public class MyMvcConfig implements WebMvcConfigurer{
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        //浏览器发送gong请求会跳转到/templates/success.html页面
        registry.addViewController("gong").setViewName("success");
    }
    //所有的WebMvcConfigurer会一起起作用
    //将组件注册到容器中
    @Bean
    public WebMvcConfigurer webMvcConfigurer() {
        WebMvcConfigurer webMvcConfigurer = new WebMvcConfigurer(){
            public void addViewControllers(ViewControllerRegistry registry) {
                registry.addViewController("/").setViewName("login");
                registry.addViewController("/login.html").setViewName("login");
                registry.addViewController("/main.html").setViewName("dashboard");
            }
            //注册拦截器
            @Override
            public void addInterceptors(InterceptorRegistry registry) {
                //super.addInterceptors(registry);
                //静态资源；  *.css , *.js
                //SpringBoot已经做好了静态资源映射
                registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**")
                        .excludePathPatterns("/login.html","/","/user/login","/asserts/**","/webjars/**");
            }
        };
        return webMvcConfigurer;
    }

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

}

4、启动服务器

首先是直接访问localhost:8080/curd/main.html

跳转到登录界面，并提示没有权限，我们输入admin+123456：

重定向的dashboard.html

dashboard.html就不贴了，太多。

至此，模拟登录功能基本完成。