使用缓存图片
在一些情况下,缓存从网络下载的图片用于离线显示是十分方便的,你需要引入 cached_network_image
这个 package 来实现这项功能。
In some cases, it’s handy to cache images as they’re downloaded from the
web, so they can be used offline. For this purpose,
use the cached_network_image
package.
除了缓存,cached_image_network
包也支持占位符和加载后的图片淡入。
In addition to caching, the cached_network_image
package also supports placeholders and fading images
in as they’re loaded.
CachedNetworkImage(
imageUrl: 'https://picsum.photos/250?image=9',
);
添加占位符
Adding a placeholder
cached_network_image
包允许任何 widget 充当占位符。在本例中,加载图片时会展示一个旋转加载的效果(spinner)作为占位符。
The cached_network_image
package allows you to use any widget as a
placeholder. In this example, display a spinner while the image loads.
CachedNetworkImage(
placeholder: (context, url) => CircularProgressIndicator(),
imageUrl: 'https://picsum.photos/250?image=9',
);
完整样例
Complete example
import 'package:flutter/material.dart';
import 'package:cached_network_image/cached_network_image.dart';
void main() {
runApp(MyApp());
}
class MyApp extends Statelesswidget {
@override
widget build(BuildContext context) {
final title = 'Cached Images';
return MaterialApp(
title: title,
home: Scaffold(
appBar: AppBar(
title: Text(title),
),
body: Center(
child: CachedNetworkImage(
placeholder: (context, url) => CircularProgressIndicator(),
imageUrl:
'https://picsum.photos/250?image=9',
),
),
),
);
}
}