14.SpringBoot2.X拦截器

1.自定义拦截器使用注解@Configuration 继承WebMvcConfigurationAdapter

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
public class CustomWebMvcConfiguer implements WebMvcConfigurer{

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginIntercepter()).addPathPatterns("/v1/**");
        WebMvcConfigurer.super.addInterceptors(registry);
    }
    
}

2.自定义拦截器 HandlerInterceptor

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class LoginIntercepter implements HandlerInterceptor{
    /**
     * 进入controller方法之前
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        System.out.println("LoginIntercepter===================preHandle");
        return HandlerInterceptor.super.preHandle(request, response, handler);
    }
    /**
     * Controller之后调用，视图渲染之前，如果控制器Controller出现了异常，则不会执行此方法
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        System.out.println("LoginIntercepter===================postHandle");
        // TODO Auto-generated method stub
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }
    /**
     *  不管有没有异常，这个afterCompletion都会被调用，用于资源清理
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        System.out.println("LoginIntercepter===================afterCompletion");
        // TODO Auto-generated method stub
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }

}

3.拦截器按照注册顺序进行拦截，先注册，先被拦截

4.拦截器不生效常见问题：

1）是否有加@Configuration
2）拦截路径是否有问题 ** 和 *
3）拦截器最后路径一定要 “/*”， 如果是目录的话则是 //

5.Filter与Interceptor

Filter 是基于函数回调 doFilter()，而Interceptor则是基于AOP思想
Filter在只在Servlet前后起作用，而Interceptor够深入到方法前后、异常抛出前后等 依赖于Servlet容器即web应用中，而Interceptor不依赖于Servlet容器所以可以运行在多种环境。
在接口调用的生命周期里，Interceptor可以被多次调用，而Filter只能在容器初始化时调用一次。 Filter和Interceptor的执行顺序 过滤前->拦截前->action执行->拦截后->过滤后