Flutter中使用已存在的sqlite数据库

1. 将数据库文件放入/根目录/assets/ 文件夹.

2. 打开pubspec.ymal文件,在flutter里加入:
   

   

   image.png

3. 打开数据库的代码:

   var databasesPath = await getDatabasesPath();
   var path = join(databasesPath, "demo_asset_example.db");
   
   // Check if the database exists
   var exists = await databaseExists(path);
   
   if (!exists) {
     // Should happen only the first time you launch your application
     print("Creating new copy from asset");
   
     // Make sure the parent directory exists
     try {
       await Directory(dirname(path)).create(recursive: true);
     } catch (_) {}
       
     // Copy from asset
     ByteData data = await rootBundle.load(join("assets", "example.db"));
     List bytes =
     data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
     
     // Write and flush the bytes written
     await File(path).writeAsBytes(bytes, flush: true);
   
   } else {
     print("Opening existing database");
   }
   // open the database
   db = await openDatabase(path, readOnly: true);
   

4. 显示查询结果,可以使用FutureBuilder:

     child: FutureBuilder(
        future: DBProvider.db.getOne(ran),
        builder: (BuildContext context, AsyncSnapshot snapshot) {
          if (snapshot.hasData) {
            print("*************");
            print(snapshot.data); //snapshot.data就是查询出来的这条数据
            daan = snapshot.data.daan;
             tigan = snapshot.data.tigan;
             xuanxiang = snapshot.data.xuanxiang;
             xuanxiang = xuanxiang.replaceAll("|", "\n");
              result = tigan + '\n\n' + xuanxiang;
            return Text(result,style:TextStyle(fontSize: 25),);
   
         } else {
            return Center(child: CircularProgressIndicator());
          }
        },
      ),