过滤器（Filter）的注册方法和 Servlet 一样，有两种方式：代码注册或者注解注册

1.代码注册方式

通过代码方式注入过滤器

@Bean
    public FilterRegistrationBean indexFilterRegistration() {
        FilterRegistrationBean registration = new FilterRegistrationBean(new IndexFilter());
        registration.addUrlPatterns("/");
        return registration;
    }

IndexFilter.Java类：

package com.example.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class IndexFilter implements Filter{

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

@Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
            throws IOException, ServletException {
        System.out.println("filter doFilter method");
        
    }

@Override
    public void init(FilterConfig arg0) throws ServletException {
        System.out.println("filter init method");
        
    }

}

2.注解方式

通过注解方式注入过滤器

IndexFilter2.java类

package com.example.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;

@WebFilter(urlPatterns = "/*", filterName = "indexFilter2")
public class IndexFilter2 implements Filter{

@Override
    public void destroy() {
        System.out.println("filter2 destroy method");
        
    }

@Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
            throws IOException, ServletException {
        System.out.println("filter2 doFilter method");
        
    }

@Override
    public void init(FilterConfig arg0) throws ServletException {
        System.out.println("filter2 init method");
        
    }

}

把注解加到入口处启动即可

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