Flutter-失败时默认映像为Image.network [英] Flutter - Default image to Image.network when it fails

问题描述

有什么方法可以控制Image.network()启动的异常，以便为它提供默认的AssetImage吗?

Is there any way you can control exceptions launched by Image.network() so you can provide it a default AssetImage ?

推荐答案

这取决于您的用例，但是一种实现方法是使用

It depends on your use case, but one way to do it is to use FadeInImage which has a property of img for the image that is intended to load, and placeholder, well, for the placeholder

FadeInImage(image: NetworkImage(url), placeholder: AssetImage(assetName)

您还可以收听直到加载图像为止，并亲自显示一个占位符，直到解析出图像为止.

You can also listen until the image is loaded and show a placeholder yourself until fetching the image resolves.

伪代码

bool _loaded = false;
var img = Image.network(src);
var placeholder = AssetImage(assetName)

@override
void initState() {
  super.initState();
  img.image.resolve(ImageConfiguration()).addListener((i, b) {
    if (mounted) {
      setState(() => _loaded = true);
    }
  });     
}

@override
Widget build(BuildContext context) { 
  return YourWidget(
    child: _loaded ? img : placeholder,
  );
}

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