通过ContentValues处理BLOB数据类型

Question

我正在尝试将图像数据存储在sqlite db中。

这样做，我首先存储在本地设备存储器中一个示例图片（路径：storage/emulation/doction/download/:)

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor> {
    private final String SAMPLE_IMAGE_PATH = "/storage/emulated/0/Download/image.jpg";

然后，我设置了一种插入方法，以这些示例数据为DB馈送：

 private void insertProduct() {
    // Create a ContentValues object where column names are the keys,
    // and sample attributes are the values.
    ContentValues values = new ContentValues();
    values.put(InventoryContract.ProductEntry.COLUMN_PRODUCT_NAME, sampleName);
    values.put(InventoryContract.ProductEntry.COLUMN_PRODUCT_QTY, sampleQty);
    values.put(InventoryContract.ProductEntry.COLUMN_PRODUCT_PRICE, SamplePrice);
    values.put(InventoryContract.ProductEntry.COLUMN_EMAIL, sampleMail);
    values.put(InventoryContract.ProductEntry.COLUMN_PHONE, samplePhone);
    values.put(InventoryContract.ProductEntry.COLUMN_PRODUCT_PIC, SAMPLE_IMAGE_PATH);
    //insert a new row
    Uri newUri = getContentResolver().insert(InventoryContract.ProductEntry.CONTENT_URI,values);
}

，我定义了onCreatEloader方法如下：

public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    // Define a projection that specifies the columns from the table we care about.
    String[] projection = {
            InventoryContract.ProductEntry._ID,
            InventoryContract.ProductEntry.COLUMN_PRODUCT_PIC,
            InventoryContract.ProductEntry.COLUMN_PRODUCT_PRICE,
            InventoryContract.ProductEntry.COLUMN_PRODUCT_QTY,
            InventoryContract.ProductEntry.COLUMN_PRODUCT_NAME};
    // This loader will execute the ContentProvider's query method on a background thread
    return new CursorLoader(this,   
            InventoryContract.ProductEntry.CONTENT_URI,   
            projection,
            null,      
            null,                   
            null);                  
}

在CursorAdapter类中，I更新了listView，添加了DB中的数据：

：

 public void bindView(View view, Context context, Cursor cursor) {
    // Find individual views that we want to modify in the list item layout
    TextView nameTextView = (TextView) view.findViewById(R.id.prod_name);
    TextView priceTextView = (TextView) view.findViewById(R.id.prod_price);
    TextView qtyTextView = (TextView) view.findViewById(R.id.prod_qty);
    ImageView prodImageView = (ImageView) view.findViewById(R.id.prod_img);
    // Find the columns of attributes that we're interested in
    int nameColumnIndex = cursor.getColumnIndex(InventoryContract.ProductEntry.COLUMN_PRODUCT_NAME);
    int priceColumnIndex = cursor.getColumnIndex(InventoryContract.ProductEntry.COLUMN_PRODUCT_PRICE);
    int qtyColumnIndex = cursor.getColumnIndex(InventoryContract.ProductEntry.COLUMN_PRODUCT_QTY);
    int picColumnIndex = cursor.getColumnIndex(InventoryContract.ProductEntry.COLUMN_PRODUCT_PIC);
    // Read the attributes from the Cursor for the current product
    String prodName = cursor.getString(nameColumnIndex);
    Double prodPrice = cursor.getDouble(priceColumnIndex);
    int prodQty = cursor.getInt(qtyColumnIndex);
    byte [] prodImg = cursor.getBlob(picColumnIndex);
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inTempStorage = new byte[1024 * 32];
    Bitmap bmp = BitmapFactory.decodeByteArray(prodImg, 0, prodImg.length, options);

    //Update Views
    nameTextView.setText(String.valueOf(prodName));
    priceTextView.setText(prodPrice.toString());
    qtyTextView.setText(String.valueOf(prodQty));
    prodImageView.setImageBitmap(bmp);
}
}

当我尝试执行此代码时，一切都很好，但是我看到一个空白的图像，而不是所选的PIC和PLACER PIC。

所以我认为将数据插入db。

Answer 1

我试图在sqlite db

中存储和检索图像数据

我不建议这样做。将图像存储在文件中。将数据存储在标识文件的行中。

然后，我设置了一种插入方法，以这些示例数据

馈送DB

您在COLUMN_PRODUCT_PIC中存储一个字符串。您不是存储byte[]。相对于我的建议，这很好。相对于您的数据 - 回程代码，这是不好的，您正在尝试检索byte[]。