PrimeFaces 6.x或更高版本

至少使用以下属性:

PrimeFaces 6.x or newer

Use at least these attributes:

<p:fileUpload ... auto="true" skinSimple="true" />

PrimeFaces 4.x/5.x

您只能为此使用CSS，因为他们删除了showButtons属性:

.ui-fileupload-buttonbar .ui-fileupload-upload {
    display: none;
}
.ui-fileupload-buttonbar .ui-fileupload-cancel {
    display: none;
}

当心CSS排序规则，另请参见如何如何使用自定义样式覆盖默认的PrimeFaces CSS?

Beware of CSS ordering rules, see also How do I override default PrimeFaces CSS with custom styles?

至少使用以下属性:

<p:fileUpload ... auto="true" showButtons="false" />