《打开资产数据库》指南介绍了在Flutter应用程序中捆绑并打开预先存在的SQLite数据库所需执行的步骤:
首先,您必须编辑
pubspec.yaml配置以引用现有的SQLite数据库文件,以便在构建应用程序时将其捆绑到您的应用程序中。在以下示例中,我们假定文件存在于
assets/demo.dbFlutter应用程序目录下:
# The following section is specific to Flutter.flutter: # The following line ensures that the Material Icons font is # included with your application, so that you can use the icons in # the material Icons class. uses-material-design: true # To add assets to your application, add an assets section, like this: assets: - assets/demo.db
接下来,在应用程序初始化中,您将需要将捆绑的文件数据复制到可用位置,因为捆绑的资源本身无法在Android上直接作为文件打开。
该
sqflite.getDatabasesPath()函数将返回用于此目的的目录。这通常类似于
/data/data/org.example.myapp/databases/Android。有了这个,您就可以从捆绑资产中加载字节数据,并创建应用程序的可写数据库文件,此处名为
app.db:
// Construct the path to the app's writable database file:var dbDir = await getDatabasesPath();var dbPath = join(dbDir, "app.db");// Delete any existing database:await deleteDatabase(dbPath);// Create the writable database file from the bundled demo database file:ByteData data = await rootBundle.load("assets/demo.db");List<int> bytes = data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);await File(dbPath).writeAsBytes(bytes);
最后,您可以在应用启动时打开创建的数据库文件:
var db = await openDatabase(dbPath);
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