使用Sqlite捕获、保存和检索图像/图片

Question

如何将图像从imageview保存到sqlite数据库，然后再次检索到Imgeview？

完整代码不工作url

Answer 1

根据您的描述，您想将ImageView图像保存到Sqlite数据库中，并将图像从Sqlite数据库加载到ImageView中，对吗？

如果是，首先，您需要创建类来加载图像：

public class Image
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public string FileName { get; set; }
public byte[] Content { get; set; }
}

然后安装sqlite net pcl以连接sqlite数据库。

最后，您可能需要考虑将imageview image转换为byte[]以进行保存，并将byte[]转换为bitmp以在imageview中加载。

请查看完整代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" 
android:orientation="vertical">
<ImageView android:id="@+id/imageView1"
android:layout_width="match_parent"
android:layout_height="wrap_content" 
android:src="@drawable/a11"/>
<Button android:id="@+id/button1" 
android:text="insert image"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<ImageView android:id="@+id/imageView2"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<Button android:id="@+id/button2" 
android:text="display image"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content" 
android:id="@+id/button3" 
android:text="create table"/>
</LinearLayout>
public class MainActivity : AppCompatActivity
{
private ImageView imageview1;
private ImageView imageview2;
private byte[] insertbitmapData;
private Button btninsert;
private Button btnload;
private Button btntable;
private SQLiteConnection _SQLiteConnection;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
Xamarin.Essentials.Platform.Init(this, savedInstanceState);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.activity_main);

btninsert = FindViewById<Button>(Resource.Id.button1);
btninsert.Click += Btninsert_Click;
btnload = FindViewById<Button>(Resource.Id.button2);
btnload.Click += Btnload_Click;
btntable = FindViewById<Button>(Resource.Id.button3);
btntable.Click += Btntable_Click;
imageview1 = FindViewById<ImageView>(Resource.Id.imageView1);
imageview2 = FindViewById<ImageView>(Resource.Id.imageView2);
}
private void Btnload_Click(object sender, System.EventArgs e)
{
string filename = "test";
var imagedata = _SQLiteConnection.Table<Image>();
var d1 = imagedata.Where(x => x.FileName == filename).FirstOrDefault();
if(d1!=null)
{
byte[] imageBytes = d1.Content;             
using (var ms = new MemoryStream(imageBytes))
{
var bitmap = BitmapFactory.DecodeStream(ms);
imageview2.SetImageBitmap(bitmap);
}
}
}
private void Btninsert_Click(object sender, System.EventArgs e)
{
Bitmap bmp = ((BitmapDrawable)imageview1.Drawable).Bitmap;
using (var stream = new MemoryStream())
{
bmp.Compress(Bitmap.CompressFormat.Png, 0, stream);
insertbitmapData = stream.ToArray();
}
Image image = new Image();
image.FileName = "test";
image.Content = insertbitmapData;
var imagedata = _SQLiteConnection.Table<Image>();
var d1 = imagedata.Where(x => x.FileName == image.FileName).FirstOrDefault();
if (d1 == null)
{
_SQLiteConnection.Insert(d1);
Console.WriteLine("Sucessfully Added");
}
else
{
Console.WriteLine("Already image id Exist");
}            
}
private void Btntable_Click(object sender, System.EventArgs e)
{
createsqlite();
}
private void createsqlite()
{
var fileName = "imagedata.db3";
var documentPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
var path = System.IO.Path.Combine(documentPath, fileName);
_SQLiteConnection = new SQLiteConnection(path);
_SQLiteConnection.CreateTable<Image>();
}
public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
{
Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
public class Image
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public string FileName { get; set; }
public byte[] Content { get; set; }
}

github:的样本

https://github.com/CherryBu/InsertImage

更新：

public class User
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public string userName { get; set; }
public string password { get; set; }
public string FileName { get; set; }
public byte[] Content { get; set; }

}