springboot 增加过滤器方法

功能检测请求的接口中是否有版本号，检查版本号的对错，并返回正确的版本号。

自定义过滤器：

package com.ruoyi.fileter;

import com.alibaba.fastjson.JSONObject;
import com.ruoyi.common.shared.ApiRespResult;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@WebFilter(filterName = "qcmappversion", urlPatterns = "/api/**")
public class MyFilter implements Filter {
    private String appVersion = "1.0";

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("----------------------->过滤器被创建");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        System.out.println("--------------------->过滤器：请求地址"+httpServletRequest.getRequestURI());
        //检查版本号
        String qcmappversion = httpServletRequest.getHeader("qcmappversion");

        if(qcmappversion == null) {
            Map<String, String> map = new HashMap<>();
            map.put("msg", "没有填写版本号");
            map.put("code", "500");
            servletResponse.setCharacterEncoding("utf-8");
            servletResponse.getWriter().print(JSONObject.toJSON(map));
            return ;
        } else if(!qcmappversion.equals(appVersion) ){
            System.out.println("--------------------->版本号"+qcmappversion);
            Map<String, String> map = new HashMap<>();
            map.put("msg", "版本号错误，正确版本号为"+appVersion);
            map.put("code", "501");
            servletResponse.setCharacterEncoding("utf-8");
            servletResponse.getWriter().print(JSONObject.toJSON(map));
            return ;
        }
        filterChain.doFilter(servletRequest, servletResponse);
        return ;
    }

    @Override
    public void destroy() {
        System.out.println("----------------------->过滤器被销毁");
    }
}

配置过滤器注入到spring容器：

package com.ruoyi.fileter;

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class WebConfiguration {
    @Bean
    public FilterRegistrationBean registerFilter() {

        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setFilter(new MyFilter());
        registration.addUrlPatterns("/api/*");
        registration.addInitParameter("paramName", "paramValue");
        registration.setName("MyFilter");
        registration.setOrder(1);
        return registration;
    }
}

此种方式配置可以实现自定义过滤URL的操作。

这里有文章实现了三种方式，可以参考：[【SpringBoot】RESTful API拦截-过滤器、拦截器、切片]（https://blog.csdn.net/zlt995768025/article/details/80171789）