Implementation code of interceptor and filter

Interceptor

1. Create a new one interceptor package

LoginInterceptor.java

import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**  Define processor interceptors  */
public class LoginInterceptor implements HandlerInterceptor {
    
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    
        if (request.getSession().getAttribute("uid") == null) {
    
            response.sendRedirect("/web/login.html");
            return false;
        }
        return true;
    }
}

2. Create a new configuration package config

LoginInterceptorConfigurer.java

import com.cy.store.interceptor.LoginInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.util.ArrayList;
import java.util.List;

/**  Register processor interceptors  */
@Configuration
public class LoginInterceptorConfigurer implements WebMvcConfigurer {
    
    /**  Interceptor configuration  */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
    
        //  Create interceptor object 
        HandlerInterceptor interceptor = new LoginInterceptor();

        //  White list 
        List<String> patterns = new ArrayList<>();
        patterns.add("/bootstrap3/**");
        patterns.add("/css/**");
        patterns.add("/images/**");
        patterns.add("/js/**");
        patterns.add("/web/register.html");
        patterns.add("/web/login.html");
        patterns.add("/web/index.html");
        patterns.add("/web/product.html");
        patterns.add("/users/reg");
        patterns.add("/users/login");
        patterns.add("/districts/**");
        patterns.add("/products/**");

        //  Add interceptors through the registration tool 
        registry.addInterceptor(interceptor).addPathPatterns("/**").excludePathPatterns(patterns);
    }
}

filter

1. To build a filter package

LoginCheckFilter.java

import com.alibaba.fastjson.JSON;
import com.itheima.reggie.common.BaseContext;
import com.itheima.reggie.common.R;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.AntPathMatcher;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/** *  Check whether the user has finished logging in  */
@WebFilter(filterName = "loginCheckFilter",urlPatterns = "/*")
@Slf4j
public class LoginCheckFilter implements Filter{
    
    // Path matcher , Support for wildcards 
    public static final AntPathMatcher PATH_MATCHER = new AntPathMatcher();

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;

        //1、 Get this request's URI
        String requestURI = request.getRequestURI();// /backend/index.html

        log.info(" Intercept request ：{}",requestURI);

        // Define the request path that does not need to be processed 
        String[] urls = new String[]{
    
                "/employee/login",
                "/employee/logout",
                "/backend/**",
                "/front/**",
                "/common/**",
                "/user/sendMsg",
                "/user/login"
        };

        //2、 Judge whether this request needs to be processed 
        boolean check = check(urls, requestURI);

        //3、 If it doesn't need to be dealt with , Then direct release 
        if(check){
    
            log.info(" This request {} No need to deal with ",requestURI);
            filterChain.doFilter(request,response);
            return;
        }

        //4-1、 Determine login status , If you are logged in , Then direct release 
        if(request.getSession().getAttribute("employee") != null){
    
            log.info(" User logged in , user id by ：{}",request.getSession().getAttribute("employee"));

            Long empId = (Long) request.getSession().getAttribute("employee");
            BaseContext.setCurrentId(empId);

            filterChain.doFilter(request,response);
            return;
        }

        //4-2、 Determine login status , If you are logged in , Then direct release 
        if(request.getSession().getAttribute("user") != null){
    
            log.info(" User logged in , user id by ：{}",request.getSession().getAttribute("user"));

            Long userId = (Long) request.getSession().getAttribute("user");
            BaseContext.setCurrentId(userId);

            filterChain.doFilter(request,response);
            return;
        }

        log.info(" The user is not logged in ");
        //5、 If you are not logged in, the result of not logging in will be returned , Response data to the client page through output stream 
        response.getWriter().write(JSON.toJSONString(R.error("NOTLOGIN")));
        return;

    }

    /** *  Path matching , Check whether this request needs to be released  * @param urls * @param requestURI * @return */
    public boolean check(String[] urls,String requestURI){
    
        for (String url : urls) {
    
            boolean match = PATH_MATCHER.match(url, requestURI);
            if(match){
    
                return true;
            }
        }
        return false;
    }
}