如何在flutter中检索sqlite数据库中的图像数据？ [英] How to retreive image data in sqlite database in flutter?

问题描述

我想用sqlite检索图像数据。我使用下面的代码

I want to retrieve image data in sqlite. im using below code

var image = await ImagePicker.pickImage(source: imageSource);
List<int> bytes = await image.readAsBytes();

我想拍摄图像并保存后sqlite.if是否可以从sqlite数据库中获取并设置图像？

i want to take image and after save it sqlite.if can get and set image from sqlite database ?.

推荐答案

我在问题中找到了解决方案。
我正在从image_picker获取图像，并将其编码为如下所示的BASE64字符串值

I found the solution in my question. I'm getting the image from an image_picker and Encode it to BASE64 string value like below

 Uint8List _bytesImage;   
 File _image;
 String  base64Image;

Future getImage() async {
     var image2 = await ImagePicker.pickImage(
      source: ImageSource.gallery,

      );
    List<int> imageBytes = image2.readAsBytesSync();
    print(imageBytes);
    base64Image = base64Encode(imageBytes);
    print('string is');
    print(base64Image);
    print("You selected gallery image : " + image2.path);

    _bytesImage = Base64Decoder().convert(base64Image);

    setState(() {

      _image=image2;

      });
}

创建一个SQLite数据库 dbhelper.dart 文件以检索字符串值，并使用数据库模型文件 Image.dart 获取并设置字符串值。

after creating an SQLite database dbhelper.dart file to retrieve String values and database model file Image.dart for the get and set the String values.

image.dart

image.dart

class Image{

  int id;
  String image;


  Employee(this.id, this.image);

   Employee.fromMap(Map map) {
    id= map[id];
    image = map[image];

  }

}

dbhelper.dart

dbhelper.dart

 class DBHelper {
  static Database _db;

  Future<Database> get db async {
    if (_db != null) return _db;
    _db = await initDb();
    return _db;
  }

  initDb() async {
    io.Directory documentsDirectory = await getApplicationDocumentsDirectory();
    String path = join(documentsDirectory.path, "test.db");
    var theDb = await openDatabase(path, version: 1, onCreate: _onCreate);
    return theDb;
  }

  void _onCreate(Database db, int version) async {
    // When creating the db, create the table
    await db.execute(
        "CREATE TABLE Imagedata(id INTEGER PRIMARY KEY, image TEXT)");
    print("Created tables");
  }

  void saveImage(Imagedata imagedata) async {
    var dbClient = await db;
    await dbClient.transaction((txn) async {
      return await txn.rawInsert(
          'INSERT INTO Imagedata(id, image) VALUES(' +
              '\'' +
              imagedata.id+
              '\'' +
              ',' +
              '\'' +
              imagedata.image +
              '\'' +
              ')');
    });
  }

  Future<List<Imagedata>> getMyImage() async {
    var dbClient = await db;
    List<Map> list = await dbClient.rawQuery('SELECT * FROM Imagedata');
    List<Imagedata> images= new List();
    for (int i = 0; i < list.length; i++) {
      images.add(new Imagedata(list[i]["id"], list[i]["image"]));
    }
    print(images.length);
    return images;
  }

   Future<int> deleteMyImage(Imagedata imagedata) async {
    var dbClient = await db;

    int res =
        await dbClient.rawDelete('DELETE * FROM Imagedata');
    return res;
  }
}

最后从数据库获取String值并解码String值

last getting String value from the database and Decode String value to the Image file.

从数据库中获取图像

      Future<List<Employee>> fetchImageFromDatabase() async {
         var dbHelper = DBHelper();
         Future<List<Imagedata>> images= dbHelper.getImages();

                 return images;
            }

在将字符串值解码到图像文件之后

after Decode string value to the Image file

    String DecoImage;
    Uint8List _bytesImage;

          FutureBuilder<List<Imagedata>>(
          future: fetchImageFromDatabase(),
          builder: (context, snapshot) {

             if (snapshot.hasData) {             
              return new
               ListView.builder(
                  itemCount: snapshot.data.length,
                  itemBuilder: (context, index) {

                      DecoImage=snapshot.data[index].image;
                     _bytesImage = Base64Decoder().convert(DecoImage);

                    return new   SingleChildScrollView(
                      child:  Container(            
                   child: _bytesImage == null 
                      ? new Text('No image value.')
                      :  Image.memory(_bytesImage)
                     ),
                    );
                   }
                 );
                }
              }
           ), 

我认为这对其他开发者，sqlite开发人员很有帮助

i think that is helpful for other flutter,sqlite developers

这篇关于如何在flutter中检索sqlite数据库中的图像数据？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！