html中的<img>的src属性取一张图片,取不到就默认
<img id="loginImg" src="/Index/1234.png" style="border-radius: 50%;" onerror="this.src='/Index/images/123.png'">
<img id="loginImg" src="/Index/1234.png" style="border-radius: 50%;" onerror="this.src='/Index/images/123.png'">