目的：springboot,实现简单的filter过滤器

环境搭建： https://blog.csdn.net/wuyinlei/article/details/79227962

项目整体目录结构：

filter 方法

package com.xdx97.backstage.filter;

//判断是否登陆的 filter

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

// /* 表示全部拦截
@WebFilter(filterName = "loginFilter",urlPatterns = "/*")
public class LoginFilter implements Filter {
    //初始化调用的方法
    //当服务器 被启动的时候，调用
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("哎呀，我被生出来了！！！");
    }

    //拦截的方法
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("哈哈 被拦截了吧！！！");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    //销毁时候调用的方法
    public void destroy() {
        System.out.println("哎呀，我要被销毁了！！！");

    }
}

controller 方法

package com.xdx97.backstage.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class BlogController {
    @RequestMapping("/aaa")
    public String aaa() {

        return "aaa";
    }

}

启动方法 App.java

package com.xdx97.backstage;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@MapperScan(basePackages = { "com.xdx97.backstage.dao" })
@ServletComponentScan(basePackages = {"com.xdx97.backstage.filter"})
public class App {

    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

如果还想要，排除某个 url

https://blog.csdn.net/amanicspater/article/details/74267444