SpringBootWeb開發-登錄和攔截器實現


引言:實現攔截器功能,這里是通過session的方式,在登錄請求發起的時候,通過往請求里添加session,request.getSession().setAttribute("loginUser","登錄成功");然后再獲取session的方式實現攔截器,登錄成功,那么session就會放進去,然后獲取session,看session是否存在,如果存在就登錄成功,否則就登錄失敗,跳轉到登錄頁。session的詳解可以參考前面的博客Java中session的詳解。

步驟:

1.首先要在前端html頁面的form表單中指定提交的地址和請求類型,也就是表單中的th:action和method

 1     <body class="text-center">
 2         <form class="form-signin" action="dashboard.html" th:action="@{/user/login}" method="post">
 3             <img class="mb-4" th:src="@{/asserts/img/bootstrap-solid.svg}" src="asserts/img/bootstrap-solid.svg" alt="" width="72" height="72">
 4             <h1 class="h3 mb-3 font-weight-normal" th:text="#{login.tip}">Please sign in</h1>
 5             <!--加一個登錄錯誤提示,這里用到了th:if-->
 6             <p style="color: red" th:text="${msg}" th:if="${not #strings.isEmpty(msg)}"></p>
 7             <label class="sr-only" th:text="#{login.username}">Username</label>
 8             <input type="text" name="username" class="form-control" placeholder="Username" th:placeholder="#{login.username}" required="" autofocus="">
 9             <label class="sr-only" th:text="#{login.password}">Password</label>
10             <input type="password" name="password" class="form-control" placeholder="Password" th:placeholder="#{login.password}" required="" autofocus="">
11             <div class="checkbox mb-3">
12                 <label>
13           <input type="checkbox" value="remember-me"> [[#{login.remember}]]
14         </label>
15             </div>
16             <button class="btn btn-lg btn-primary btn-block" type="submit" th:text="#{login.btn}">Sign in</button>
17             <p class="mt-5 mb-3 text-muted">© 2017-2018</p>
18             <a class="btn btn-sm" th:href="@{/login.html(l='zh_CN')}">中文</a>
19             <a class="btn btn-sm" th:href="@{/login.html(l='en_US')}">English</a>
20         </form>
21     </body>

2.編寫Controller層,代碼解析看注釋。這里所有的html頁面都是通過thymeleaf模板引擎解析的

 1 package com.xiaoma.springbootweb.controller;
 2 
 3 import org.springframework.stereotype.Controller;
 4 import org.springframework.util.StringUtils;
 5 import org.springframework.web.bind.annotation.PostMapping;
 6 import org.springframework.web.bind.annotation.RequestParam;
 7 
 8 import javax.servlet.http.HttpServletRequest;
 9 import java.util.Map;
10 
11 @Controller
12 public class LoginController {
13     //PostMapping可以直接發post請求
14     @PostMapping(value = "/user/login")
15     //通過RequestParam獲取用戶名和密碼,map里用來存放錯誤信息
16     public String login(@RequestParam("username") String username,
17                         @RequestParam("password") String password,
18                         Map<String,Object> map, HttpServletRequest request){
19         //如果用戶名不為空並且密碼為123456則登錄成功,否則登錄失敗並給出錯誤提示
20         if(!StringUtils.isEmpty(username)&&"123456".equals(password)){
21             request.getSession().setAttribute("loginUser","登錄成功");
22             //為了防止表單重復提交,這里用重定向,這里的main.html通過MyMvcConfig中的視圖映射,會將頁面跳轉到templates下的dashboard.html頁面
23             return "redirect:/main.html";
24         }
25         else{
26             map.put("msg","用戶名或者密碼錯誤");
27             return "login";
28         }
29     }
30 }

3.編寫攔截器

 1 package com.xiaoma.springbootweb.component;
 2 
 3 import org.springframework.web.servlet.HandlerInterceptor;
 4 import org.springframework.web.servlet.ModelAndView;
 5 
 6 import javax.servlet.http.HttpServletRequest;
 7 import javax.servlet.http.HttpServletResponse;
 8 
 9 public class LoginHandlerInterceptor implements HandlerInterceptor {
10     @Override
11     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
12         Object user=request.getSession().getAttribute("loginUser");
13         System.out.println("獲取的session為"+user);
14         if(user==null){
15             //設置登錄失敗的提示信息
16             request.setAttribute("msg","沒有權限,請先登錄");
17             //登錄失敗,返回登陸頁面
18             request.getRequestDispatcher("/index.html").forward(request,response);
19             return false;
20         }
21         else{
22             //登錄成功,進入后台
23             return true;
24         }
25     }
26 
27     @Override
28     public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
29         HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
30     }
31 
32     @Override
33     public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
34         HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
35     }
36 }

4.在我們的MyMvcConfig.java頁面注冊攔截器

 1 package com.xiaoma.springbootweb.config;
 2 
 3 import com.xiaoma.springbootweb.component.LoginHandlerInterceptor;
 4 import com.xiaoma.springbootweb.component.MyLocaleResolver;
 5 import org.springframework.context.annotation.Bean;
 6 import org.springframework.context.annotation.Configuration;
 7 import org.springframework.web.servlet.LocaleResolver;
 8 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
 9 import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
10 import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
11 
12 @Configuration
13 public class MyMvcConfig extends WebMvcConfigurerAdapter {
14     @Override
15     public void addViewControllers(ViewControllerRegistry registry) {
16         registry.addViewController("atguigu").setViewName("success");
17     }
18 
19     //通過bean注解將組件注冊到loc容器中,讓springmvc知道這個組件的存在
20     @Bean
21     //通過mvc視圖解析器實現controller層的mapping映射功能
22     public WebMvcConfigurerAdapter webMvcConfigurerAdapter(){
23         WebMvcConfigurerAdapter adapter = new WebMvcConfigurerAdapter() {
24             @Override
25             public void addViewControllers(ViewControllerRegistry registry) {
26             registry.addViewController("/").setViewName("login");
27             registry.addViewController("/index.html").setViewName("login");
28             registry.addViewController("/main.html").setViewName("dashboard");
29             }
30 
31             //注冊登錄攔截器
32             @Override
33             public void addInterceptors(InterceptorRegistry registry) {
34                 registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**").
35                         excludePathPatterns("/","/index.html","/user/login");
36             }
37         };
38         return adapter;
39     }
40 
41     @Bean
42     public LocaleResolver localeResolver(){
43         return new MyLocaleResolver();
44     }
45 }

 


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