springboot实现过滤器的示例代码

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("com.ts.myt.dao")
@ServletComponentScan // 过滤器
public class MytApplication {
    public static void main(String[] args) {
        SpringApplication.run(MytApplication.class, args);
    }
}

import com.alibaba.fastjson.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * @Author:sgw
 * @Date:2023/9/15
 * @Description: 使用注解方式实现过滤器（@WebFilter）
 */
@WebFilter(urlPatterns = "/user/*", filterName = "filter1")
public class MyFilter implements Filter {
    private static final Logger logger = LoggerFactory.getLogger(MyFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
//        Filter.super.init(filterConfig);
        logger.info("MyFilterInit1");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException, IOException {
        logger.info("doFilter");
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        String token = request.getHeader("token");
        logger.info("token值：{}", token);

        if (token != null) {
            //该方法执行后直接运行至下一个过滤器
            filterChain.doFilter(servletRequest, servletResponse);
        } else {
            servletResponse.setCharacterEncoding("UTF-8");
            servletResponse.setContentType("application/json; charset=utf-8");
            PrintWriter out = servletResponse.getWriter();
            JSONObject res = new JSONObject();
            res.put("msg", "错误");
            res.put("success", "false");
            out.append(res.toString());
        }
    }

    @Override
    public void destroy() {
//        Filter.super.destroy();
        logger.info("destroy");
    }
}

import com.alibaba.fastjson.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * @Author:sgw
 * @Date:2023/9/15
 * @Description: 过滤器实现方式二：使用非注解方式实现过滤器（直接注入到spring中）
 */
public class MyFilter2 implements Filter {
    private static final Logger logger = LoggerFactory.getLogger(MyFilter2.class);
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        logger.info("MyFilterInit2");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException, IOException {
        System.out.println("doFilter");
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        String token = request.getHeader("token");
        System.out.println(token);
        //该方法执行后直接运行至下一个过滤器
        if(token!=null){
            filterChain.doFilter(servletRequest, servletResponse);
        }else{
            servletResponse.setCharacterEncoding("UTF-8");
            servletResponse.setContentType("application/json; charset=utf-8");
            PrintWriter out = servletResponse.getWriter();
            JSONObject res = new JSONObject();
            res.put("msg", "错误");
            res.put("success", "false");
            out.append(res.toString());
        }
    }

    @Override
    public void destroy() {
        System.out.println("destroy");
    }
}

import com.ts.myt.filter.MyFilter2;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
 * @Author:sgw
 * @Date:2023/9/15
 * @Description: 方式二的过滤器配置文件
 */
@Configuration
public class MyFilter2Config {
    // Filter代码类
    @Bean
    public MyFilter2 myFilter2() {
        return new MyFilter2();
    }

    @Bean
    public FilterRegistrationBean getFilterRegistrationBean(MyFilter2 myFilter2) {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(myFilter2);
        filterRegistrationBean.setOrder(2);
        filterRegistrationBean.addUrlPatterns("/user/*");
        filterRegistrationBean.setName("tokenFilter2");
        return filterRegistrationBean;
    }
}