flutter 清除缓存

在Flutter中清除缓存可以通过以下步骤实现[^1]：

1. 导入`path_provider`包：

import 'package:path_provider/path_provider.dart';

2. 获取缓存目录：

Directory cacheDir = await getTemporaryDirectory();

3. 计算缓存大小：

int cacheSize = 0;
List<FileSystemEntity> files = cacheDir.listSync(recursive: true);
for (FileSystemEntity file in files) {
  if (file is File) {
    cacheSize += await file.length();
  }
}

4. 删除缓存文件：

for (FileSystemEntity file in files) {
  if (file is File) {
    await file.delete(recursive: true);
  }
}

下面是一个完整的示例代码：

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Cache Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Cache Demo'),
      ),
      body: Center(
        child: RaisedButton(
          child: Text('Clear Cache'),
          onPressed: () async {
            Directory cacheDir = await getTemporaryDirectory();
            int cacheSize = 0;
            List<FileSystemEntity> files = cacheDir.listSync(recursive: true);
            for (FileSystemEntity file in files) {
              if (file is File) {
                cacheSize += await file.length();
              }
            }
            for (FileSystemEntity file in files) {
              if (file is File) {
                await file.delete(recursive: true);
              }
            }
            showDialog(
              context: context,
              builder: (BuildContext context) {
                return AlertDialog(
                  title: Text('Cache Cleared'),
                  content: Text('Cache size: ${cacheSize ~/ 1024} KB'),
                  actions: <Widget>[
                    FlatButton(
                      child: Text('OK'),
                      onPressed: () {
                        Navigator.of(context).pop();
                      },
                    ),
                  ],
                );
              },
            );
          },
        ),
      ),
    );
  }
}