1.简介

Spring MVC提供了拦截器方便在接口调用前后进行一些通用处理。

2.步骤

1.实现一个拦截器类，共有三处拦截时机：

public class Interceptor1 implements HandlerInterceptor {//实现HandlerInterceptor接口//执行handler之前调用//编码格式处理，登录保护，权限处理@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("Interceptor1.preHandle");return true;//拒绝还是通过}//handler执行完毕后执行//检查敏感词汇@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("Interceptor1.postHandle");HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);}//整体处理完毕执行@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("Interceptor1.afterCompletion");HandlerInterceptor.super.afterCompletion(request, response, handler, ex);}
}

2.在配置类中注册拦截类：

public class MvcConfig implements WebMvcConfigurer {//实现WebMvcConfigurer接口
...@Overridepublic void addInterceptors(InterceptorRegistry registry){//方法 1.注册拦截类，拦截全部请求registry.addInterceptor(new Interceptor1());//方法 2.指定地址拦截//通配符：* ：一层字符 **：多层字符registry.addInterceptor(new Interceptor1()).addPathPatterns("/product/**");//方法 3.排除拦截registry.addInterceptor(new Interceptor1()).addPathPatterns("/user/***").excludePathPatterns("/user/data1");//如果有多个拦截类优先级如何？registry.addInterceptor(new Interceptor1())//先声明优先级高，先进后出.addPathPatterns("/product/**");registry.addInterceptor(new Interceptor2())//后声明优先级低，后进先出.addPathPatterns("/product/**");
}