项目实战一：springboot 写个简单过滤器

步骤：

1.在启动类上加注解：@ServletComponentScan，用来扫描发现过滤器

package com.ithm.reggie;

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

2.编写过滤器

@WebFilter：标准该类是个过滤器

filterName  ：过滤器名

urlPatterns ：拦截路径

package com.itheima.reggie.filter;



import lombok.extern.slf4j.Slf4j;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


/**
 * 检查用户是否已经完成登录
 */
@WebFilter(filterName = "loginCheckFilter",urlPatterns = "/*")
@Slf4j
public class LoginCheckFilter implements Filter{


    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        //放行,执行后续代码
        filterChain.doFilter(request,response);
    }


}