Spring 框架中拦截器与过滤器的区别及拦截器使用详解

//被扫描
@Component
public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle Interceptor");
//        return可返回两种值  ： true  拦截放行   false  拦截不放行
        //判断用户是否登录，获取Session中存的会话
        Object username = request.getSession().getAttribute("username");
        //username == null  说明username未存入会话，用户没有登录
        if (username != null){
            System.out.println("已登录");
            return true;
        }
        //向前端发出响应
        response.getWriter().write("notlogin");
        return false;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle Interceptor");
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion Interceptor");
    }
}

@Configuration
@EnableWebMvc
public class SpringMvc implements WebMvcConfigurer {
    @Autowired
    private LoginInterceptor loginInterceptor;
//    拦截器拦截路径和排除路径
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginInterceptor).addPathPatterns("/api");
    }
}

@RestController
@RequestMapping("/api")
public class apiController {
    @GetMapping
    public String login() {
        System.out.println("Controller！");
        return "登录成功";
    }