WebView调用了onReceivedError之后，还是调用onPageFinished。

http://stackoverflow.com/questions/23808868/is-onpagefinished-is-called-after-onreceivederror-in-anyway

可以看到

onPageFinished

 tells
you that the WebView has stopped loading. 

onReceivedError

 tells
you there was an error. They're not "success" and "failure" callbacks which is why you'll get both in case of an error.

onPageFinished仅仅表示网页加载完成了，不能说明这个网页是否成功的加载了。

Android 网络] WebView如何判断页面真正成功加载? 

http://www.eoeandroid.com/thread-304637-1-1.html?_dsign=f339dc4e

[Android
网络] 判断webview加载网页是否完全加载成功

http://www.eoeandroid.com/forum.php?mod=viewthread&tid=327795&extra=page%3D1&page=2


解决方案：webview加载网页，网页中js可以判断图片是否加载完成，判断之后调用本地代码通知一下就知道了