SpringBoot+拦截器

实现登录拦截器：

1. 用户未登录时访问/logout或/center会被拦截
2. 用户已登录时访问/logout或/center不会被拦截
3. 用户登录后访问过/logout后再次访问/center会被拦截
4. 被拦截后，将会被redirect至/error页面

1. UserController

@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private User user;
@RequestMapping("/login/{username}/{password}")
public String login(
@PathVariable("username") String username,
@PathVariable("password") String password,
HttpServletRequest request){
user.setName(username);
//将user对象存入session中
request.getSession().setAttribute("user",user);
return user.getName()+" login success";
}

@RequestMapping("/logout")
public String logout(HttpServletRequest request){
//从session中获取user对象
User logoutUser = (User) request.getSession().getAttribute("user");
request.getSession().removeAttribute("user");
return logoutUser.getName()+" logout success";
}

@RequestMapping("/center")
public String center(HttpServletRequest request){
//从session中获取user对象
User centerUser = (User) request.getSession().getAttribute("user");
return "User center: "+centerUser.getName();
}

@RequestMapping("/error")
public String error(){
return "error, you haven't login";
}
}

2. 实现拦截器UserInterceptor

public class UserInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//从本地获取cookie，判断是否已经存在user
User user = (User) request.getSession().getAttribute("user");
if (user == null) {
// 如果session中没有user，则重定向至error
response.sendRedirect("/user/error");
return false;
}
return true;
}
}

3. @Configuration配置拦截器

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {
@Override
public void addInterceptors(org.springframework.web.servlet.config.annotation.InterceptorRegistry registry) {
String[] addpath = {
"/user/"
};
String[] excludePath={
"/user/login/",//login若不被排除，那么无法登录
"/user/error",//error若不被排除，那么进入error后会再次被拦截，形成死循环
};
registry.addInterceptor(new UserInterceptor()).addPathPatterns(addpath).excludePathPatterns(excludePath);
}
}