SpringBoot之请求拦截

Filter 过滤器

1、编写过滤器TestFilter 继承javax.servlet.Filter

@Component
public class TestFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("加载拦截器");
    }

    /**
    * 过滤后的处理操作
    */
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("开始拦截");
        Date startTime = new Date();
        //对请求进行处理
        chain.doFilter(request,response);
        Date endTime = new Date();
        System.out.println("结束拦截");
        System.out.println("总用时" + (endTime.getTime() - startTime.getTime()));
    }


    @Override
    public void destroy() {
        System.out.println("销毁拦截器");
    }
}

注释：@Component注解把我们写好的Filter注入到Spring容器中
2、编写Controller，用于测试Filter

@RestController        //spring boot注解 @RestController = @Controller + @ResponseBody
@RequestMapping("/test")    //controller请求路径
public class TestController {
    @GetMapping( "get_user")
    public SR getUser() {
        System.out.println("调用getUser服务");
        User user = User.builder()
                .age(16)
//               .name("张三")
                .sex("男")
                .birthday(new Date())
                .build();
        return SR.ok(user);
    }

}

运行服务测试，访问刚才写好的controller

我们的Filter已经拦截到了请求。

拦截器 Interceptor

1、编写拦截器TestInterceptor继承HandlerInterceptor

@Component
public class TestInterceptor implements HandlerInterceptor {

    /**
     * 进入controller方法之前调用
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle");
        request.setAttribute("startTime",System.currentTimeMillis());
        return true;
    }

    /**
     * controller方法结束之后调用如果有controller方法有异常则不会调用
     * @param request
     * @param response
     * @param handler
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandler");
        System.out.println(System.currentTimeMillis() - (Long)request.getAttribute("startTime")+ "秒");

    }

    /**
     * controller方法之后调用
     * @param request
     * @param response
     * @param handler
     * @param ex
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion");
        System.out.println(System.currentTimeMillis() - (Long)request.getAttribute("startTime")+ "秒");
    }
}

写完拦截器我们对他进行注册，让Springboot能加载到，注册类

@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Autowired
    private TestInterceptor testInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(testInterceptor);
    }
}

启动服务访问接口：

拦截器已经成功拦截

下面进行postHandler异常测试
在控制器里随便抛出一个异常

结果：
postHandler没有

在异常后面我们还会发现一组拦截到信息

这时候我们发现有postHandler，这是因为拦截器会拦截所有的controller，包括Spring自己的controller，后面就是在出现异常后Spring会进入一个ErrorController里。这时候就会被拦截了。