关于过滤器的路径

老师，为什么之前学过滤器的时候，我们是这样设置的

package com.mason.web.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

@WebFilter("/CharacterEncodingFilter")
public class CharacterEncodingFilter implements Filter {
    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        chain.doFilter(req, resp);
    }

    public void init(FilterConfig config) throws ServletException {

    }

}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <filter>
        <filter-name>characterEncoding</filter-name>
        <filter-class>com.mason.web.filter.CharacterEncodingFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>characterEncoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

先设置@WebFilter("/CharacterEncodingFilter")

然后在xml中注册过滤器

<filter>
    <filter-name>characterEncoding</filter-name>
    <filter-class>com.mason.web.filter.CharacterEncodingFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>characterEncoding</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

但为什么视频中老师是直接把@WebFilter("/*")就可以了呢？

不需要在XML中注册以及配置过滤器吗？