Spring boot 配置自己的拦截器

框架使用的是spring boot 2.0

首先，自定义拦截器实现HandlerInterceptor接口，preHandler是在执行controller方法前执行的  此外还有两个方法，具体作用最后才说，先熟悉以下拦截器的使用流程。

 @Component
 public class PassportInterceptor implements HandlerInterceptor{

     @Override
     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
             throws Exception {
         HttpSession session = request.getSession();
         User user  = (User)session.getAttribute("user");
         if(user == null) {
             response.sendRedirect("/login");
             return false;
         }
         return true;
     }

 }

上面拦截器只是简单的通过session验证是否登录

定义了自己的拦截器后就要实现 WebMvcConfigurer接口 注：该接口好像是spring boot 2.0以后有的  之前不是这个接口 该接口提供了方法添加拦截器，加上@Component注解  让其能被ioc容器管理

 @Component
 public class LabWebConfiguration implements WebMvcConfigurer{

     @Autowired
     PassportInterceptor passportInterceptor;

     @Override
     public void addInterceptors(InterceptorRegistry registry) {

         registry.addInterceptor(passportInterceptor)
             .addPathPatterns("/**")
             .excludePathPatterns("/stylesheets/**", "/javascripts/**","/fonts/**",
                     "/images/**", "/login/**", "/regist/**");
     }

 }

registry有三个重要的方法，addInterceptors()方法将自定义的拦截器添加进去 addPathPatterns 方法的主要作用是添加拦截器要拦截的路径，excludePathPatterns的功能则是配置对某些路径放行。上面我针对自己的静态资源、还有登录注册页面放行

接下来做一个小小的测试  测试以下拦截器各个方法的执行顺序

 @Controller
 public class TestController {

     @RequestMapping("/test")
     @ResponseBody
     public String testInterceptor() {

         System.out.println("Controller方法执行");

         return "test";
     }

 }

 @Component
 public class TestInterceptor implements HandlerInterceptor{

     @Override
     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
             throws Exception {
         System.out.println("preHandler执行了");
         return true;
     }
     @Override
     public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
             ModelAndView modelAndView) throws Exception {
         System.out.println("postHandler执行了");
     }
     @Override
     public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
             throws Exception {
         // TODO Auto-generated method stub
         System.out.println("afterCompletion执行了");
     }

 }

 @Component
 public class LabWebConfiguration implements WebMvcConfigurer{
     @Autowired
     TestInterceptor testInterceptor;

     @Override
         public void addInterceptors(InterceptorRegistry registry) {
             registry.addInterceptor(testInterceptor)
                 .addPathPatterns("/test");
         }

 }

结果如下

可见preHander方法只在Controller执行前   return true则放行

postHandler则是在 具体的Controller方法执行后执行

afterCompletion  看资料说是在页面渲染完成后执行   因此可以用来作为资源的清理工作