Flutter图片缓存优化

import'package:cached_network_image/cached_network_image.dart';
import'package:flutter/material.dart';
voidmain() {
runApp(MyApp());
}
classMyAppextendsStatelessWidget {
@overrideWidgetbuild(BuildContextcontext) {
returnMaterialApp(
title: 'Flutter Demo',
home: MyHomePage(),
    );
  }
}
classMyHomePageextendsStatelessWidget {
finalimageUrl="https://picsum.photos/250?image=9";
@overrideWidgetbuild(BuildContextcontext) {
returnScaffold(
appBar: AppBar(
title: Text('Flutter Demo'),
      ),
body: Center(
child: CachedNetworkImage(
imageUrl: imageUrl,
progressIndicatorBuilder: (context, url, downloadProgress) =>CircularProgressIndicator(value: downloadProgress.progress),
errorWidget: (context, url, error) =>Icon(Icons.error),
        ),
      ),
    );
  }
}