插入sqlite flutter 不冻结界面

我正在尝试使用 flutter 在 sqlite 内存数据库中插入大量行（大约 12k 或更多）。

我从 API 获取数据并使用计算函数来处理来自 Json 的数据。 现在我需要将这些数据添加到内存中的数据库中，为此我使用批量事务。

batchInsertEventSong(List<EventSong> rows) async {
   Database db = await instance.database;
   db.transaction((txn) async {
      Batch batch = txn.batch();
      for (var song in rows) {
         Map<String, dynamic> row = {
           DatabaseHelper.columnIdSong: song.id,
           DatabaseHelper.columnTitle: song.title,
           DatabaseHelper.columnInterpreter: song.interpreter
         };
         batch.insert(table, row);
       }
      batch.commit();
   }
}

但是这个函数在插入过程中阻塞了我的用户界面，我也尝试使用计算，但我无法传递类数据库或类批处理。 我不清楚如何在另一个线程中执行此进程，或者（因为我不能使用隔离）执行而不阻塞我的 UI。

有什么建议吗？

更新2020 - 05 - 15

这是行不通的，请参阅：

• 无法从另一个隔离调用平台通道方法·问题#13937·flutter/flutter https://github.com/flutter/flutter/issues/13937

注：完整代码见文末

第 1 步：使你的方法静态并使其无效

  static batchInsertEventSong(List<EventSong> rows) {
    Database db = await instance.database;
    db.transaction((txn) async {
        Batch batch = txn.batch();
        for (var song in rows) {
            Map<String, dynamic> row = {
            DatabaseHelper.columnIdSong: song.id,
            DatabaseHelper.columnTitle: song.title,
            DatabaseHelper.columnInterpreter: song.interpreter
            };
            batch.insert(table, row);
        }
        batch.commit();
    }
  }

第 2 步：创建新方法（通常但不需要为相同名称添加 Async）

  Future batchInsertEventSongAsync(List<EventSong> rows) {

  }

第 3 步：使用静态方法调用compute并返回

  return compute(batchInsertEventSong, rows);

步骤 [1,2,3] 代码审查

  Future batchInsertEventSongAsync(List<EventSong> rows) {
    return compute(_batchInsertEventSong, rows);
  }

  static _batchInsertEventSong(List<EventSong> rows) {
    Database db = await instance.database;
    db.transaction((txn) async {
        Batch batch = txn.batch();
        for (var song in rows) {
            Map<String, dynamic> row = {
            DatabaseHelper.columnIdSong: song.id,
            DatabaseHelper.columnTitle: song.title,
            DatabaseHelper.columnInterpreter: song.interpreter
            };
            batch.insert(table, row);
        }
        batch.commit();
    }
  }

完整代码

import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(body: MyHomePage(title: 'Flutter Demo Home Page')),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            FlatButton.icon(
              icon: Icon(Icons.backup),
              label: Text("Long Opreation"),
              onPressed: () async {
                var rows = await RsetApi.getRawsAsync();
                await Database._saveRaws(rows);
              },
            ),
            FlatButton.icon(
              icon: Icon(Icons.backup),
              label: Text("Short Opreation"),
              onPressed: () {
                Scaffold.of(context).hideCurrentSnackBar();
                Scaffold.of(context).showSnackBar(new SnackBar(
                  content: new Text(DateTime.now().toIso8601String()),
                ));
              },
            ),
          ],
        ),
      ),
    );
  }
}

class RsetApi {
  static Future<List<EventSong>> getRawsAsync() {
    return compute(_getRaws, null);
  }

  static List<EventSong> _getRaws(pram1) {
    var rows = List<EventSong>();
    for (var i = 1; i < 12000; i++) {
      rows.add(EventSong(i));
      print("fetching raws " + (i / 12000).toString());
    }
    return rows;
  }
}

class Database {
  static Future saveRawsAsync(List<EventSong> rows) {
    return compute(_saveRaws, rows);
  }

  static _saveRaws(List<EventSong> rows) {
    for (var i = 1; i < rows.length; i++) {
      print("saving raws " + (i / rows.length).toString());
    }
  }
}

class EventSong {
  int id;
  EventSong(this.id);
}

Ref:

• 在后台解析 JSON - Flutter https://flutter.dev/docs/cookbook/networking/background-parsing#4-move-this-work-to-a-separate-isolate

不重要参考：

• Flutter async：重型起重操作的初学者友好指南 https://blog.usejournal.com/flutter-async-beginner-friendly-guide-for-heavy-lifting-operations-cf8ec81833d7?gi=c61a4a7f641d

• Dart/Flutter：转换时间戳 - Thinbug https://stackoverflow.com/questions/50632217/dart-flutter-converting-timestamp

• 显示小吃栏 - Flutter https://flutter.dev/docs/cookbook/design/snackbars

• sdk/file.dart 位于 1c4ad14fa3a0a1d5ecea10e3b04befecee3ffbcb · dart-lang/sdk https://github.com/dart-lang/sdk/blob/1c4ad14fa3a0a1d5ecea10e3b04befecee3ffbcb/sdk/lib/io/file.dart

• sdk/file_impl.dart 位于 1c4ad14fa3a0a1d5ecea10e3b04befecee3ffbcb · dart-lang/sdk https://github.com/dart-lang/sdk/blob/1c4ad14fa3a0a1d5ecea10e3b04befecee3ffbcb/sdk/lib/io/file_impl.dart