我不知道这是否是使用 SQLite 节省存储空间的最佳方法，我仍在寻找它，但我们开始了。
您可以选择图片的来源，例如图库或相机，下面是代码。
private void selectProductImage() {
final CharSequence[] itens = {"Use Camera", "Gallery", "Cancel"};
AlertDialog.Builder builder = new AlertDialog.Builder(this,R.style.AlertDialog);
builder.setItems(itens, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (itens[which].equals("Use Camera")) {
Toast.makeText(YourActivity.this, "Use Camera", Toast.LENGTH_SHORT).show();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(new String[]{Manifest.permission.CAMERA}, MY_CAMERA_PERMISSION_CODE);
} else {
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, CAMERA_REQUEST);
}
} else if (itens[which].equals("Gallery")) {
Toast.makeText(YourActivity.this, "Gallery", Toast.LENGTH_SHORT).show();
Intent galleryIntent = new Intent();
galleryIntent.setAction(Intent.ACTION_GET_CONTENT);
galleryIntent.setType("image/*");
startActivityForResult(galleryIntent, REQUEST_GALLERY_PHOTO);
} else if (itens[which].equals("Cancel")) {
dialog.dismiss();
}
}
});
builder.show();
}
也许您需要获得使用相机的权限
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == MY_CAMERA_PERMISSION_CODE) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
//Toast.makeText(this, "camera permission granted", Toast.LENGTH_LONG).show();
Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(cameraIntent, CAMERA_REQUEST);
} else {
Toast.makeText(this, "camera permission denied", Toast.LENGTH_LONG).show();
}
return;
}
}
这里是如何处理来自您选择的来源的图像。
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CAMERA_REQUEST && resultCode == Activity.RESULT_OK) {
Bitmap bitmap = Bitmap.createScaledBitmap((Bitmap) data.getExtras().get("data"),96, 96, true);
mProductImage.setImageBitmap(bitmap);
isPriviteImage = true;
}
if (requestCode == REQUEST_GALLERY_PHOTO && resultCode == RESULT_OK && data != null) {
//mProductImage.setImageURI(data.getData());
// INSERT IMAGE INTO SQLite
Uri uri = data.getData();
try {
InputStream inputStream = getContentResolver().openInputStream(uri);
Bitmap bitmap = Bitmap.createScaledBitmap(BitmapFactory.decodeStream(inputStream),96, 96, true);
mProductImage.setImageBitmap(bitmap);
isPriviteImage = true;
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
}
正如您在我的示例中所看到的，没有地方可以保存您选择 camera 的图像，我将图像放在名为 mProductImage 的 ImageView 变量上.
从现在开始，您可以使用 按钮 将图像保存在 SQLite 数据库中。这是您可以使用的功能。
private void saveImage() {
productTablePath = Environment.getExternalStorageDirectory()+"/YourAditionalPath/";
ProductDatabaseHelper productDatabaseHelper = new ProductDatabaseHelper(getApplicationContext(), "dbname.db", productTablePath);
productListTable = productDatabaseHelper.getWritableDatabase();
productRepository = new ProductRepository(productListTable);
try {
if (isPriviteImage) {
productRepository.addProduct(imageViewToByte(mProductImage));
isPriviteImage = false;
} else {
productRepository.addProduct(null);
}
mProductImage.setImageResource(R.drawable.shopping_cart_black_48dp);
} catch (Exception e) {
e.printStackTrace();
}
}
imageViewToByte 函数在哪里：
private byte[] imageViewToByte(CircleImageView image) {
Bitmap bitmap = ((BitmapDrawable)image.getDrawable()).getBitmap();
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG,100,stream);
byte[] byteArray = stream.toByteArray();
return byteArray;
}
现在您需要实现 SQLiteOpenHelper。您需要为此创建一个新类。我为此使用的 java 文件名是 ProductDatabaseHelper.java。
public class ProductDatabaseHelper extends SQLiteOpenHelper {
private static int dbVersion = 1;
public ProductDatabaseHelper(Context context, String name, String storageDirectory) {
super(context, storageDirectory+name, null, dbVersion);
}
@Override
public void onCreate(SQLiteDatabase db) {
StringBuilder sql = new StringBuilder();
sql.append("CREATE TABLE IF NOT EXISTS PRODUCTLIST (");
sql.append(" IMAGE BLOB,");
db.execSQL(sql.toString());
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
现在您需要实现 CRUD（创建新项目、读取、更新和删除）。
public class ProductRepository {
SQLiteDatabase instance;
public ProductRepository(SQLiteDatabase instance) {
this.instance = instance;
}
public void addProduct(byte[] image){
ContentValues contentValues = new ContentValues();
contentValues.put("IMAGE",image);
instance.insertOrThrow("PRODUCTLIST",null, contentValues);
}
}
值得一提的是，图像的压缩是在onActivityResult() 中针对源图像（相机和画廊）进行的。
使用命令：
Bitmap bitmap = Bitmap.createScaledBitmap(capturedImage, width, height, true);
除此之外，这里有一个链接，我们可以在这里阅读一些关于压缩的内容。
https://androidwave.com/capture-image-from-camera-gallery/
如果您有更好的方法来压缩图像以保存在 SQLite 数据库中，请在此处发布您的代码！