1、创建自定义过滤器LoginCheckFiler

1.1通过@WebFilter创建过滤器

1.2 验证是否可以拦截请求

1.3 代码

package com.example.ruiji_demo;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@Slf4j
@SpringBootApplication
@ServletComponentScan
public class RuijiDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(RuijiDemoApplication.class, args);
        log.info("项目启动成功");
    }

}

2、在启动类加入注解@ServletComponentScan 用来扫描过滤器

触发所有的过滤器@ServletComponentScan

3、完善过滤器的处理逻辑

3.1判断是否需要是要放行的请求

3.2判断用户是否登录

3.3如果没有登录返回请求体并携带msg信息

package com.example.ruiji_demo.filter;

import com.alibaba.fastjson2.JSON;
import com.example.ruiji_demo.common.R;
import jakarta.servlet.*;
import jakarta.servlet.annotation.WebFilter;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.AntPathMatcher;

import java.io.IOException;
import java.util.logging.LogRecord;

/**
 * @author jitwxs
 * @date 2024年03月25日 22:24
 */
@WebFilter(filterName = "loginCheckFilter", urlPatterns = "/*")
@Slf4j
public class LoginCheckFilter implements Filter {
//    路径匹配器,支持通配符
    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、获取本次请求的url
        String requestUrl = request.getRequestURI();
//        2、定义不需要处理的路径
        String[] urls = new String[]{
                "/employee/login",
                "/employee/logout",
                "/backeed/**",
                "/front/**"
        };
//        3、判断本次请求是否需要处理,调用匹配路径
        boolean check =  check(urls,requestUrl);

//        4.检测路径是否需要筛选如果不需要筛选直接放行
        if(check){
            filterChain.doFilter(request,response);
            return;
        }
//        5.判断是否登录过
        if(request.getSession().getAttribute("employee") != null){
            filterChain.doFilter(request,response);
            return;
        }

//        6.如果没有登录过,通过输出流方向客户端页面响应数据
        response.getWriter().write(JSON.toJSONString(R.error("NOTLOGIN")));
        return;
    }

    /**
     * 匹配路径,检查本次请求是否需要放行
     * @param urls
     * @param requestUrl
     * @return
     */
    public boolean check(String[] urls,String requestUrl){
        for(String url:urls){
            boolean match = PATH_MATCHER.match(url,requestUrl);
            log.info("match:{}",match);
            if(match){
                return true;
            }
        }
        return false;
    }
}