SpringBoot过滤器的使用（两种方法以及使用场景）

一、@WebFilter + @ServletComponentScan注解，多个过滤器无法自定义顺序。

1、自定义过滤器 ReqResFilter 必须实现 javax.servlet.Filter。然后添加注解 @WebFilter（javax.servlet.annotation.WebFilter），urlPatterns 过滤器要过滤的URL规则配置，filterName 过滤器的名称。配置如下：

package com.wenbei.filter;
import lombok.extern.slf4j.Slf4j;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
@Slf4j
@WebFilter(urlPatterns = "/*", filterName = "reqResFilter")
public class ReqResFilter implements Filter {
    
    
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    
    
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse 			      servletResponse, FilterChain filterChain) 
            throws IOException, ServletException {
    
    
        log.info("=============自定义过滤器============");
        filterChain.doFilter(servletRequest,servletResponse);
    }
    @Override
    public void destroy() {
    
    
    }
}

2、在启动类上加

添加
@ServletComponentScan

二、自定义配置类配置过滤器

1、单个过滤器时，自定义配置类加载自定义过滤器 ReqResFilter，还是刚才那个自定义过滤器，只不过上面的两个注解都可以去掉了。

@Configuration
public class WebConfig {
    
    
    @Bean
    public FilterRegistrationBean reqResFilter() {
    
    
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        ReqResFilter reqResFilter = new ReqResFilter();
        filterRegistrationBean.setFilter(reqResFilter);　　　　 filterRegistrationBean.addUrlPatterns("*.json");//配置过滤规则 　　　　 return filterRegistrationBean;
　　} }

2、多个过滤器时如何配置
新增一个类

public class ReqResFilter1 implements Filter {
    
    
    private static Logger logger = LoggerFactory.getLogger(ReqResFilter1.class);
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    
    
        //获取 filterRegistrationBean.addInitParameter("name","hahahhhaa")设置的参数
        System.out.println("init=============="+filterConfig.getInitParameter("name"));
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    
    
        System.out.println("2222222222222222222222222222");
        filterChain.doFilter(servletRequest,servletResponse);
    }
    @Override
    public void destroy() {
    
    
    }
}

修改配置类

@Configuration
public class WebConfig {
    
    

    @Bean
    public FilterRegistrationBean reqResFilter1() {
    
    
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();

        ReqResFilter1 reqResFilter1 = new ReqResFilter1();

        filterRegistrationBean.setFilter(reqResFilter1);
        filterRegistrationBean.addUrlPatterns("*.json");//配置过滤规则
        filterRegistrationBean.addInitParameter("name","hahahhhaa");//设置init参数
        filterRegistrationBean.setName("reqResFilter1");//设置过滤器名称
        filterRegistrationBean.setOrder(2);//执行次序

        return filterRegistrationBean;
    }

    @Bean
    public FilterRegistrationBean reqResFilter() {
    
    
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();

        ReqResFilter reqResFilter = new ReqResFilter();

        filterRegistrationBean.setFilter(reqResFilter);

 //配置多个过滤规则
//        List<String> urls = new ArrayList<>();
//        urls.add("/order/*");
//        urls.add("/user/*");
//        filterRegistrationBean.setUrlPatterns(urls);

        filterRegistrationBean.addUrlPatterns("*.json");//配置过滤规则
        filterRegistrationBean.setName("reqResFilter");//设置过滤器名称
        filterRegistrationBean.setOrder(1);//执行次序
        return filterRegistrationBean;
    }
}