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。

 1 @Component
 2 public class PassportInterceptor implements HandlerInterceptor{
 3     
 4     @Override
 5     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
 6             throws Exception {
 7         HttpSession session = request.getSession();
 8         User user  = (User)session.getAttribute("user");
 9         if(user == null) {
10             response.sendRedirect("/login");
11             return false;
12         }
13         return true;
14     }
15     
16 }

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

 1 @Component
 2 public class LabWebConfiguration implements WebMvcConfigurer{
 3     
 4     @Autowired
 5     PassportInterceptor passportInterceptor;
 6     
 7     @Override
 8     public void addInterceptors(InterceptorRegistry registry) {
 9         
10         registry.addInterceptor(passportInterceptor)
11             .addPathPatterns("/**")
12             .excludePathPatterns("/stylesheets/**", "/javascripts/**","/fonts/**",
13                     "/images/**", "/login/**", "/regist/**");
14     }
15     
16 
17 }

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

 1 @Controller
 2 public class TestController {
 3 
 4     @RequestMapping("/test")
 5     @ResponseBody
 6     public String testInterceptor() {
 7         
 8         System.out.println("Controller方法执行");
 9         
10         return "test";
11     }
12     
13 }

 1 @Component
 2 public class TestInterceptor implements HandlerInterceptor{
 3     
 4     @Override
 5     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
 6             throws Exception {    
 7         System.out.println("preHandler执行了");    
 8         return true;
 9     }
10     @Override
11     public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
12             ModelAndView modelAndView) throws Exception {
13         System.out.println("postHandler执行了");    
14     }
15     @Override
16     public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
17             throws Exception {
18         // TODO Auto-generated method stub
19         System.out.println("afterCompletion执行了");    
20     }
21     
22 }

 1 @Component
 2 public class LabWebConfiguration implements WebMvcConfigurer{
 3     @Autowired
 4     TestInterceptor testInterceptor;
 5     
 6     @Override
 7         public void addInterceptors(InterceptorRegistry registry) {
 8             registry.addInterceptor(testInterceptor)
 9                 .addPathPatterns("/test");
10         }
11     
12 
13 }

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