Java Web过滤器的核心原理、实现与执行顺序配置方法(最新整理)

package jakarta.servlet;
import java.io.IOException;
public interface Filter {
    default void init(FilterConfig filterConfig) throws ServletException {
    }
    void doFilter(ServletRequest var1, ServletResponse var2, FilterChain var3) throws IOException, ServletException;
    default void destroy() {
    }
}

filterChain.doFilter(servletRequest, servletResponse);

package org.araby.blognovelink.filter;
import jakarta.servlet.*;
import jakarta.servlet.annotation.WebFilter;
import lombok.extern.slf4j.Slf4j;
import java.io.IOException;
@Slf4j
@WebFilter("/*")
public class CharsetFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.info("初始化统一字符编码过滤器");
        Filter.super.init(filterConfig);
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("统一字符编码过滤器开始执行");
        servletRequest.setCharacterEncoding("UTF-8");
        servletResponse.setCharacterEncoding("UTF-8");
        filterChain.doFilter(servletRequest, servletResponse);
    }
    @Override
    public void destroy() {
        log.info("销毁统一字符编码过滤器");
        Filter.super.destroy();
    }
}

@SpringBootApplication
@ServletComponentScan
public class BlogNovelinkApplication {
    public static void main(String[] args) {
        SpringApplication.run(BlogNovelinkApplication.class, args);
    }
}

import jakarta.servlet.*;
import jakarta.servlet.annotation.WebFilter;
import jakarta.servlet.http.HttpServletRequest;
import lombok.extern.slf4j.Slf4j;
import java.io.IOException;
@Slf4j
@Component
public class LogFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.info("初始化日志过滤器");
        Filter.super.init(filterConfig);
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("日志过滤器开始执行");
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        String uri = request.getRequestURI();
        String method = request.getMethod();
        String ip = request.getRemoteAddr();
        long startTime = System.currentTimeMillis();
        filterChain.doFilter(servletRequest, servletResponse);
        // 记录响应耗时
        long costTime = System.currentTimeMillis() - startTime;
        log.info("Response - URL: {}, Cost Time: {}ms", uri, costTime);
    }
    @Override
    public void destroy() {
        log.info("销毁日志过滤器");
        Filter.super.destroy();
    }
}

import org.araby.blognovelink.filter.AFilter;
import org.araby.blognovelink.filter.BFilter;
import org.araby.blognovelink.filter.CFilter;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class WebConfig {
    @Bean
    public FilterRegistrationBean<AFilter> aFilter() {
        FilterRegistrationBean<AFilter> bean = new FilterRegistrationBean<>();
        bean.setFilter(new AFilter());
        bean.addUrlPatterns("/*");
        bean.setOrder(1); // 最先执行
        return bean;
    }
    @Bean
    public FilterRegistrationBean<BFilter> bFilter() {
        FilterRegistrationBean<BFilter> bean = new FilterRegistrationBean<>();
        bean.setFilter(new BFilter());
        bean.addUrlPatterns("/*");
        bean.setOrder(2);
        return bean;
    }
    @Bean
    public FilterRegistrationBean<CFilter> cFilter() {
        FilterRegistrationBean<CFilter> bean = new FilterRegistrationBean<>();
        bean.setFilter(new CFilter());
        bean.addUrlPatterns("/*");
        bean.setOrder(3); // 最后执行
        return bean;
    }
}