Spring MVC 拦截器总结

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
    @Override
    public 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
    @Override
    public 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
    @Override
    public 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
...
    @Override
    public 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/**");
}