如何在springboot使用拦截器

前言

记录软件开发点滴，积累知识和经验（第三篇）

要做什么？

目标：学会使用拦截器（Interceptor）

怎样去做？

• 写一个拦截器类实现HandlerInterceptor（JwtAuthInterceptor.java）

package com.wyl.interceptors;

import com.wyl.utils.JwtUtil;
import org.apache.commons.lang.StringUtils;
import org.springframework.lang.Nullable;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

/**
 * @ClassName JwtAuthInterceptor
 * @Description 拦截器
 * @Author yilongwu
 * @DATE 2019-06-14 14:35
 * @Version 1.0.0
 **/
public class JwtAuthInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        String token = request.getHeader("X-ToKen");
        if (StringUtils.isBlank(token)) {
            response.sendRedirect("/VR/login/noPermission");
            return false;
        }
        String name = JwtUtil.validateToken(token);
        request.setAttribute("name", name);
        return true;
    }

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

由于我使用了JWT验证，所以这个拦截器的作用是拦截token.关于JWT可以去了解下官网

• 配置拦截器，将拦截器类注入到springmvc中

package com.wyl.config;

import com.wyl.interceptors.JwtAuthInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * @ClassName InterceptorConfigs
 * @Description
 * @Author yilongwu
 * @DATE 2019-06-14 14:55
 * @Version 1.0.0
 **/
@Configuration
public class InterceptorConfigs implements WebMvcConfigurer {

    /**
     * 登录访问控制拦截器
     * @param registry
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        JwtAuthInterceptor jwtAuthInterceptor = new JwtAuthInterceptor();
        InterceptorRegistration interceptorRegistration = registry.addInterceptor(jwtAuthInterceptor);
        interceptorRegistration.addPathPatterns("/**");
        interceptorRegistration.excludePathPatterns("/login/**","/swagger-ui.html","/webjars/**","/swagger-resources/**","/v2/**");
    }
}

• 关于三个重写方法的作用

// 这个是在请求到达之前进行拦截
 default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return true;
    }
    // 这个是在请求到达后，在渲染视图之前进行拦截
    default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
    }
    
    // 这个是在渲染完视图后，做一些处理
    default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
    }

结果怎么样？

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