Flutter数据库与偏好设置插件sqflite_preferences的使用

sqflite_preferences 是一个通过 sqflite 库来模拟 sharedpreferences 行为的方法。它提供了快速保存和检索数据的能力，并且不需要操作成为异步操作。

使用

如何使用

首先导入库：

// 导入库
import 'package:sqflite_preferences/sqflite_preferences.dart';
// 引用管理数据库的单例类
var dbHelper = DatabaseHelper.instance;

初始化数据库

initDatabase() async {
  await dbHelper.initDatabase('phoneNumber', 'INTEGER');
}

设置布尔值

setBoolValue() async {
  await dbHelper.setBool('flag', true);
}

获取布尔值

var boolValue;
getBoolValue() async {
  boolValue = await dbHelper.getBool('flag');
}

设置整数值

setIntValue() async {
  await dbHelper.setInt('number', 1);
}

获取整数值

var intValue;
getIntValue() async {
  intValue = await dbHelper.getInt('number');
}

设置浮点数值

setRealValue() async {
  await dbHelper.setReal('real', 1.555);
}

获取浮点数值

var realValue;
getRealValue() async {
  realValue = await dbHelper.getReal('real');
}

设置Blob值

dynamic response = await get(url);
dynamic bytesFromPic = response.image.bodyBytes;
setBlobValue() async {
  await dbHelper.setBlob('pic', bytesFromPic);
}

获取Blob值

var blobValue;
getBlobValue() async {
  blobValue = await dbHelper.getBlob('pic');
}
// 示例：Image.memory(blobValue),

设置字符串值

setStringValue() async {
  await dbHelper.setString('name', 'someone name');
}

获取字符串值

var stringValue;
getStringValue() async {
  stringValue = await dbHelper.getString('name');
}

获取行数

rowCount() async {
  await dbHelper.queryRowCount('name');
}

删除保存的数据

deleteValue() async {
  await dbHelper.delete('name');
}

示例

以下是一个完整的示例代码，展示了如何使用 sqflite_preferences 插件来存储和获取数据。

import 'package:flutter/material.dart';
import 'package:sqflite_preferences/sqflite_preferences.dart';

var dbHelper = DatabaseHelper.instance;
var value;

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

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({required this.title}) : super(key: null);

  final String title;

  [@override](/user/override)
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  var textValue;

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Container(
              padding: EdgeInsets.all(50),
              child: TextField(
                onChanged: (value) async {
                  textValue = value;
                  await dbHelper.setString('value', textValue);
                },
              ),
            ),
            MaterialButton(
              child: Text("Get Value"),
              onPressed: () async {
                value = await dbHelper.getString('value');
              },
            ),
            MaterialButton(
              child: Text("Go to next page"),
              onPressed: () {
                Navigator.of(context).push(
                  MaterialPageRoute(
                      fullscreenDialog: true,
                      builder: (BuildContext ctx) {
                        return Page2();
                      }),
                );
              },
            ),
          ],
        ),
      ),
    );
  }
}

class Page2 extends StatefulWidget {
  [@override](/user/override)
  _Page2State createState() => _Page2State();
}

class _Page2State extends State<Page2> {
  [@override](/user/override)
  Widget build(BuildContext context) {
    var width = MediaQuery.of(context).size.width;
    return Scaffold(
      appBar: AppBar(
          // title: Text(widget.title),
          ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Center(
            child: Container(
              padding: EdgeInsets.all(30),
              width: width,
              child: FittedBox(
                child: Text(
                  "$value",
                  style: TextStyle(color: Colors.black, fontSize: 30),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}