springboot的拦截器

首先要写一个自己的拦截器，实现HandlerInterceptor接口，并且实现接口中的三个方法，同时添加  @Component  注解，把自己的拦截器放入容器 中管理，方便以后的注入使用。

@Component
public class MyIntercepor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("前值方法");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("后置方法");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("完成方法");
    }
}

然后要写一个配置类，用来添加拦截器到 配置类中，让拦截器启用，因为使用的是springboot所以配置类要 使用@Configuration注解，标明本类是配置类

并且要继承WebMvcConfigurer这个接口，并且注入自己写的拦截器，并且从写public void addInterceptors(InterceptorRegistry registry)这个方法，注册自己写的拦截器，

@Configuration
public class MyWebMvcConfig implements WebMvcConfigurer {
    @Autowired
    private MyIntercepor myIntercepor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(myIntercepor).addPathPatterns("/**");
    }
}

结果

2020-05-01 17:40:41.708 DEBUG 9812 --- [nio-8888-exec-1] o.s.b.f.s.DefaultListableBeanFactory     : Returning cached instance of singleton bean 'userController'
2020-05-01 17:40:41.709 DEBUG 9812 --- [nio-8888-exec-1] o.s.web.servlet.DispatcherServlet        : Last-Modified value for [/user/hello] is: -1
前值方法
2020-05-01 17:40:41.764 DEBUG 9812 --- [nio-8888-exec-1] m.m.a.RequestResponseBodyMethodProcessor : Written [this is hello controller] as "text/html" using [org.springframework.http.converter.StringHttpMessageConverter@31ceba99]
后置方法
2020-05-01 17:40:41.766 DEBUG 9812 --- [nio-8888-exec-1] o.s.web.servlet.DispatcherServlet        : Null ModelAndView returned to DispatcherServlet with name 'dispatcherServlet': assuming HandlerAdapter completed request handling
完成方法
2020-05-01 17:40:41.766 DEBUG 9812 --- [nio-8888-exec-1] o.s.web.servlet.DispatcherServlet        : Successfully completed request
2020-05-01 17:40:41.767 DEBUG 9812 --- [nio-8888-exec-1] o.s.b.w.s.f.OrderedRequestContextFilter  : Cleared thread-bound request context: org.apache.catalina.connector.RequestFacade@388e5df3