Springboot中的自定义拦截器及原理详解

package com.atspring.config;
import com.atspring.intercepter.LoginInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
/**
 * 配置web请求中的设置
 */
@Configuration
public class AdminWebConfig implements WebMvcConfigurer {
    /**
     * 1.编写一个拦截器，注册到容器中，addInterceptors
     * 2.指定拦截规则，如果拦截所有，所有资源包括静态资源都会被拦截
     * @param registry
     */
    //webconfig中的增加拦截器的方法，只需要重写就可以
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
//        LoginInterceptor loginInterceptor=new LoginInterceptor();
//        registry.addInterceptor(loginInterceptor);
        registry.addInterceptor(new LoginInterceptor())
                //添加拦截器拦截的路径，/**全部放行，但在实际项目中可能是域名 /lucas/**
                .addPathPatterns("/**")
                //放行静态资源，以及登录
                .excludePathPatterns("/login","/css/**","/image/**","/js/**");
    }
}

package com.atspring.intercepter;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
 * 登录检查
 * 1.配置拦截器拦截哪些请求，
 * 2.把配置放在容器中Aop
 */
public class LoginInterceptor  implements HandlerInterceptor {
    /**
     * 处理方法之前，资源请求，
     * 检查等
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
       //登录检查,这里就利用session简单的存储了
        HttpSession  session=request.getSession();
        Object loginUser = session.getAttribute("loginUser");
        if (loginUser!=null){
            //放行
            return  true;
        }
        //拦截成功
        request.setAttribute("message","请先登录");
        //转发到登录页面去登录，并且返回
        request.getRequestDispatcher("/login").forward(request,response);
        return false;
    }
    /**
     * 处理方法之后，未返回页面之前
     * 对于数据处理
     * @param request
     * @param response
     * @param handler
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }
    /**
     * 请求执行完成之后，
     * 对资源的关闭等
     * @param request
     * @param response
     * @param handler
     * @param ex
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

server.port=8086
server.servlet.context-path=/
spring.mvc.view.prefix=/views/
spring.mvc.view.suffix=.jsp

@Configuration
public class InterceptorConfig extends WebMvcConfigurationSupport {
    @Autowired
    private LoginHandlerInterceptor loginHandlerInterceptor;
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("forward:/index");
        registry.setOrder(Ordered.HIGHEST_PRECEDENCE);
        super.addViewControllers(registry);
    }
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // 判断用户是否登录的拦截器
        registry.addInterceptor(loginHandlerInterceptor).addPathPatterns("/*/*");
        super.addInterceptors(registry);
    }
}

    private static final String VIEW_PREFIX = "/views/";// 视图前缀
    private static final String VIEW_SUFFIX = ".jsp";// 视图后缀
    private static final String VIEW_CONTENT_TYPE = "text/html;charset=UTF-8";//视图的内容类型。
    /**
     * 配置 视图解析器
     * @return
     */
    @Bean
    public ViewResolver viewResolver(){
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setCache(true);
        resolver.setPrefix(VIEW_PREFIX);
        resolver.setSuffix(VIEW_SUFFIX);
        resolver.setExposeContextBeansAsAttributes(true);
        resolver.setContentType(VIEW_CONTENT_TYPE);
        return resolver;
    }