SpringMVC拦截器简单使用

介绍

拦截器一般用在某个方法被访问之前进行拦截，然后在方法执行之前或之后加入某些操作。

使用

1、创建一个SpringBoot工程，定义一个自定义拦截器类，实现HandlerInterceptor接口，重写三个方法。

public class MyInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle.....");
        //简单实现对是否登录的判断
        User user = (User) request.getSession().getAttribute("loginUser");

        if(user != null){
            return true;
        }
        return false;
    }

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

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

方法分析

preHandle()在请求方法之前执行，返回值为boolean类型，true表示请求继续执行，false表示请求结束。

postHandle()在请求处理完成，dispatcherServlet返回视图后执行。

afterCompletion()在dispatcherServlet渲染视图后执行。

2、编写拦截器配置类

@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //拦截所有请求
        String[] addPathPatterns = {"/**"};
        //不需要拦截的请求
        String[] excludePathPatterns = {"/page/logout","/page/login","/page/init","/reader/login"};
        registry.addInterceptor(new MyInterceptor()).addPathPatterns(addPathPatterns).excludePathPatterns(excludePathPatterns);
        super.addInterceptors(registry);
    }
}