它是从此类生成的
org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter：
private String generateLoginPageHtml(HttpServletRequest request, boolean loginError, boolean logoutSuccess) { String errorMsg = "none"; [...] StringBuilder sb = new StringBuilder(); sb.append("<html><head><title>Login Page</title></head>"); if (formLoginEnabled) { sb.append("<body onload='document.f.").append(usernameParameter).append(".focus();'>n"); } [...]
