对于没有访问权限的用户需要转到登录表单页面。要实现访问控制的方法多种多样，可以通过Aop、拦截器实现，也可以通过框架实现（如：Apache Shiro、Spring Security）。
pom.xml添加依赖
1 <dependency>
2 <groupId>org.springframework.boot</groupId>
3 <artifactId>spring-boot-starter-web</artifactId>
4 </dependency>
5
6 <dependency>
7 <groupId>org.springframework.boot</groupId>
8 <artifactId>spring-boot-starter-thymeleaf</artifactId>
9 </dependency>
10 <dependency>
11 <groupId>org.springframework.boot</groupId>
12 <artifactId>spring-boot-starter-security</artifactId>
13 </dependency>
创建SpringSecurity配置类
1 import org.springframework.beans.factory.annotation.Autowired;
2 import org.springframework.context.annotation.Configuration;
3 import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
4 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
5 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
6 import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
7
8 @Configuration
9 @EnableWebSecurity
10 public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
11
12 @Override
13 protected void configure(HttpSecurity http) throws Exception {
14 http
15 .authorizeRequests()
16 .antMatchers("/", "/home").permitAll()
17 .anyRequest().authenticated()
18 .and()
19 .formLogin()
20 .loginPage("/login")
21 .permitAll()
22 .and()
23 .logout()
24 .permitAll();
25 }
26
27 @Autowired
28 public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
29 //inMemoryAuthentication 从内存中获取
30 auth
31 .inMemoryAuthentication()
32 .passwordEncoder(new BCryptPasswordEncoder())
33 .withUser("admin")
34 .password(new BCryptPasswordEncoder()
35 .encode("123456")).roles("USER");
36 }
37 }
通过@EnableWebSecurity注解开启Spring Security的功能
继承WebSecurityConfigurerAdapter，并重写它的方法来设置一些web安全的细节
configure(HttpSecurity http)方法，通过authorizeRequests()定义哪些URL需要被保护、哪些不需要被保护。例如以上代码指定了/和/home不需要任何认证就可以访问，其他的路径都必须通过身份验证。
通过formLogin()定义当需要用户登录时候，转到的登录页面。
configureGlobal(AuthenticationManagerBuilder auth)方法，在内存中创建了一个用户，该用户的名称为admin，密码为123456，用户角色为USER。
控制器：
1 @Controller
2 public class HelloController {
3
4 @RequestMapping("/")
5 public String index() {
6 return "index";
7 }
8
9 @RequestMapping("/hello")
10 public String hello() {
11 return "hello";
12 }
13
14 @RequestMapping(value = "/login", method = RequestMethod.GET)
15 public String login() {
16 return "login";
17 }
18
19 }
index.html
1 <!DOCTYPE html>
2 <html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"
3 xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">
4 <head>
5 <title>Spring Security入门</title>
6 </head>
7 <body>
8 <h1>欢迎使用Spring Security!</h1>
9
10 <p>点击 <a th:href="@{/hello}">这里</a> 打个招呼吧</p>
11 </body>
12 </html>
hello.html
1 <!DOCTYPE html>
2 <html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"
3 xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">
4 <head>
5 <title>Hello World!</title>
6 </head>
7 <body>
8 <h1 th:inline="text">Hello [[${#httpServletRequest.remoteUser}]]!</h1>
9 <form th:action="@{/logout}" method="post">
10 <input type="submit" value="注销"/>
11 </form>
12 </body>
13 </html>
login.html
1 <!DOCTYPE html>
2 <html xmlns="http://www.w3.org/1999/xhtml"
3 xmlns:th="http://www.thymeleaf.org"
4 xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">
5 <head>
6 <title>Spring Security Example </title>
7 </head>
8 <body>
9 <div th:if="${param.error}">
10 用户名或密码错
11 </div>
12 <div th:if="${param.logout}">
13 您已注销成功
14 </div>
15 <form th:action="@{/login}" method="post">
16 <div><label> 用户名 : <input type="text" name="username"/> </label></div>
17 <div><label> 密 码 : <input type="password" name="password"/> </label></div>
18 <div><input type="submit" value="登录"/></div>
19 </form>
20 </body>
21 </html>
运行：
打开index.html，点击这里，如果没有登录进入登录页，已登录跳转到hello.html