方式一

1. 创建过滤器实现类实现Filter接口。并添加@WebFilter注解。

@WebFilter(urlPatterns = {"/student"})
public class StudentFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("过滤器执行...");
        String username = servletRequest.getParameter("username");
        if(username.contains("sb")){
            username = username.replaceAll("sb","*");
        }
        System.out.println(username);
        servletRequest.setAttribute("username",username);
        filterChain.doFilter(servletRequest, servletResponse);
    }
}

2. 在springBoot入口类配置@ServletComponentScan注解

方式二

1. 创建一个普通的Filter实现类，不添@WebFilter注解。

public class UserFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("过滤器执行...");
        String username = servletRequest.getParameter("username");
        if(username.contains("sb")){
            username = username.replaceAll("sb","*");
        }
        System.out.println(username);
        servletRequest.setAttribute("username",username);
        filterChain.doFilter(servletRequest, servletResponse);
    }
}

2. 创建过滤器核心配置类。

@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean filterRegistrationBean(){
        FilterRegistrationBean<UserFilter> filter = new FilterRegistrationBean<>(new UserFilter());
        filter.addUrlPatterns("/user");
        return filter;
    }
}