为什么过滤器会在项目刚启动访问主页时执行两次，之后正常访问一次打印一次？

@WebFilter(filterName = "Filter01",value = "/*")
public class Filter01 implements Filter {
    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        System.out.println("过滤器开始");
        chain.doFilter(req, resp);
        System.out.println("执行完了");
    }

    public void init(FilterConfig config) throws ServletException {

    }

}

主页init 调用了2次后端

public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
    System.out.println("拦截了");
    chain.doFilter(req, resp);
}

看这个方法参数，请求和响应调用了一次，Filter调用一次，而/*是过滤所有，所有会打印两次。