方式一

自定义Filter类实现Filter接口，添加@WebFilter注解

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

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

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("=================this is filer method====================");
        filterChain.doFilter(servletRequest, servletResponse);
    }

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

在SpringBoot项目启动类上加@ServletComponentScan注解

@SpringBootApplication
// SpringBoot启动时自动扫描@WebServlet和@WebFilter
@ServletComponentScan
public class SpringbootDemoApplication {
	public static void main(String[] args) {
		SpringApplication.run(SpringbootDemoApplication.class, args);
	}
}

访问测试

http://localhost:8081/hello?name=SpringBoot

方式二

自定义Filter类实现Filter接口，但是不需要添加@WebFilter注解

public class TestFilter implements Filter {

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

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("=================this is filer method====================");
        filterChain.doFilter(servletRequest, servletResponse);
    }

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

启动类中注册filter为一个bean

注意：在SpringBoot项目启动类上不需要加@ServletComponentScan注解

@SpringBootApplication
public class SpringbootDemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(SpringbootDemoApplication.class, args);
	}

	@Bean
	public FilterRegistrationBean getFilterRegistrationBean() {
		FilterRegistrationBean registrationBean = new FilterRegistrationBean(new TestFilter());
		registrationBean.addUrlPatterns("/test");
		return registrationBean;
	}
}

测试