我正在使用Flutter，我需要将SQLite中的图像保存为BLOB，然后将其显示在我的页面中。
我将其作为字符串进行，它工作正常，但不是 1.5 MB 大小的图像，应用程序出现异常，我尝试将其作为 blob 进行，但我在任何地方都找不到任何教程。
我的型号：
import 'package:flutter/services.dart';
const String tablePersonal = 'personal_info';
class PersonalFields {
static final List<String> values = [
id,
name,
logo,
];
static const String id = '_id';
static const String name = 'name';
static const String logo = 'logo';
}
class PersonalInfoModel {
int? id;
final String name;
final Uint8List? logo;
PersonalInfoModel({
this.id,
required this.name,
this.logo,
});
PersonalInfoModel copy({
int? id,
String? name,
Uint8List? logo,
}) =>
PersonalInfoModel(
id: id ?? this.id,
name: name ?? this.name,
logo: logo ?? this.logo,
);
static PersonalInfoModel fromJson(Map<String, Object?> json) =>
PersonalInfoModel(
id: json[PersonalFields.id] as int?,
name: json[PersonalFields.name] as String,
logo: json[PersonalFields.logo] as Uint8List?,
);
Map<String, dynamic> toJson() => {
PersonalFields.id: id,
PersonalFields.name: name,
PersonalFields.logo: logo,
};
}
SQL Helper：创建表后，我只需插入空记录来保存 id = 1，以便我只更新记录。这意味着该表只会获得一条记录。
batch.execute('''
CREATE TABLE IF NOT EXISTS $tablePersonal
(
${PersonalFields.id} $idType,
${PersonalFields.name} $textType,
${PersonalFields.logo} $blobType
)
''');
batch.execute('''
INSERT INTO $tablePersonal
(
${PersonalFields.name}
)
VALUES
(
''
)
''');
//read personal info
Future<List<PersonalInfoModel>> getPesonalInfo() async {
var db = await instanace.database;
final result = await db.query(tablePersonal);
return result.map((json) => PersonalInfoModel.fromJson(json)).toList();
}
Future<int> updatePersonalInfo(PersonalInfoModel personalInfoModel) async {
final db = await instanace.database;
return db.update(
tablePersonal,
personalInfoModel.toJson(),
where: '${PersonalFields.id} = ?',
whereArgs: [personalInfoModel.id],
);
}
我的页面：
import 'dart:convert';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:image_picker/image_picker.dart';
import 'package:ledger/database/sql_helper.dart';
import 'package:ledger/l10n/app_local.dart';
import 'package:ledger/models/personal_info_model.dart';
class PersonalInfoPage extends StatefulWidget {
const PersonalInfoPage({Key? key}) : super(key: key);
@override
State<PersonalInfoPage> createState() => _PersonalInfoPageState();
}
class _PersonalInfoPageState extends State<PersonalInfoPage> {
final _formKey = GlobalKey<FormState>();
final TextEditingController _nameController = TextEditingController();
double boxWidth = 10;
double boxHieght = 10;
XFile? xImage;
var bytes;
final ImagePicker _picker = ImagePicker();
late List<PersonalInfoModel> personalList;
late PersonalInfoModel existPersonal;
bool isLoading = true;
@override
void initState() {
super.initState();
getPersonalInfo();
}
Future pickImage() async {
try {
xImage = await _picker.pickImage(source: ImageSource.gallery);
if (xImage == null) return;
final imagePath = File(xImage!.path);
bytes = imagePath;
setState(() {});
} on PlatformException catch (e) {
print('Failed to pick image: $e');
}
}
Future getPersonalInfo() async {
final data = await SQLHelper.instanace.getPesonalInfo();
setState(() {
personalList = data;
getData();
isLoading = false;
});
}
getData() {
existPersonal = personalList.firstWhere((element) => element.id == 1);
_nameController.text = existPersonal.name;
bytes = existPersonal.logo;
}
Future updatePersonalInfo(PersonalInfoModel personalInfoModel) async {
await SQLHelper.instanace.updatePersonalInfo(personalInfoModel);
getPersonalInfo();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(AppLocal.loc.personal_info),
actions: [
IconButton(
onPressed: () {
PersonalInfoModel personalInfoModel = PersonalInfoModel(
id: 1,
name: _nameController.text,
logo: bytes);
updatePersonalInfo(personalInfoModel);
},
icon: const Icon(Icons.save_as_outlined),
),
],
),
body: isLoading
? const Center(child: CircularProgressIndicator())
: SingleChildScrollView(
child: Column(
children: [
Padding(
padding: const EdgeInsets.symmetric(horizontal: 5.0),
child: Form(
key: _formKey,
child: Column(
children: [
SizedBox(height: boxHieght),
TextFormField(
controller: _nameController,
decoration: InputDecoration(
filled: true,
labelText: AppLocal.loc.name,
border: const OutlineInputBorder(
borderRadius: BorderRadius.all(
Radius.circular(5.0),
),
),
),
),
],
),
),
),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
TextButton(
onPressed: () {
print('xxxxxx');
pickImage();
},
child: Text('from Gallary'),
),
],
),
Container(
color: Colors.grey.shade100,
height: 150,
width: 150,
child: bytes != null
? Image.memory(bytes)
: Image.asset('assets/logo.png'),
),
],
),
),
);
}
}
以下是如何将其转换为 blob 并将其保存到 SQLite
Future pickImage(ImageSource source) async {
try {
final image = await ImagePicker.pickImage(source: source);
final imagePath = File(image.path);
List<int> bytes = await image.readAsBytes();
String base64 = base64Encode(bytes);// here it is. Save it to sqflite
} on PlatformException catch (e) {
print(e);
}
}
用于从 SQLite 获取
String blobImageFromSqflite; //get from sqflite
Uint8List _bytesImage = Base64Decoder().convert(blobImageFromSqflite);
to display it;
Image.memory(
_bytesImage,
);
///import 'package:image/image.dart' as Image1;
// final bytes = await File(pickedFilePath).readAsBytes();
// final pickedImage = Image1.decodeImage(bytes);
// Uint8List imageBytes =
//Uint8List.fromList(Image1.encodeJpg(pickedImage));
Future<Uint8List?> photo_dataByEntryID(BuildContext context,{required String imageId)
{
Uint8List? imageData = null;
await db.query('image',columns: ['image'],where: 'id = ${imageId}').then((value) async {
if(value.length > 0)
{
Uint8List? imageDataProcess = value[0]['image'] as Uint8List?;
imageData = imageDataProcess!;
}
}).onError((error, stackTrace) async {
print(error.toString());
});
return imageData;
}