java - 将图像保存到 sqlite 数据库后图像不显示

Question

在这个应用程序中，我将产品保存在 sqlite 数据库中。你能帮我理解为什么我要编辑产品时看不到图像吗？添加时我可以看到它，但单击产品进行编辑时看不到它。

public class EditorActivity extends AppCompatActivity implements
        LoaderManager.LoaderCallbacks<Cursor>{

private static final int EXISTING_PRODUCT_LOADER = 1;

private static final int PICTURE_GALLERY_REQUEST = 1;

private static final String STATE_PICTURE_URI = "STATE_PICTURE_URI";

private Uri mPictureUri;

private Uri mCurrentProductUri;

private EditText mNameEditText;

private EditText mPriceEditText;

private EditText mQuantityEditText;

private EditText mSupplierEditText;

private EditText mMailEditText;

private int mProductQuantity=-1;

private Button mIncreaseQuantityButton;
private Button mDecreaseQuantityButton;

private Button mSelectImageButton;

private ImageView mProductImageView;

private String picturePath;

private String stringUri;

private Button mOrderButton;

final Context mContext = EditorActivity.this;

private boolean mProductHasChanged = false;

private View.OnTouchListener mTouchListener = new View.OnTouchListener() {
    @Override
    public boolean onTouch(View view, MotionEvent motionEvent) {
        mProductHasChanged = true;
        return false;
    }
};

public static Bitmap getImage(byte[] image) {
    return BitmapFactory.decodeByteArray(image, 70, image.length);
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.editor_activity);

    Intent intent = getIntent();
    mCurrentProductUri = intent.getData();

    if (mCurrentProductUri == null) {
        setTitle(getString(R.string.editor_activity_title_new_product));

        invalidateOptionsMenu();
    } else {
        setTitle(getString(R.string.editor_activity_title_edit_product));

        getLoaderManager().initLoader(EXISTING_PRODUCT_LOADER, null, this);
    }

    initialiseViews();

    setOnTouchListener();
}
private void setOnTouchListener() {
    mNameEditText.setOnTouchListener(mTouchListener);
    mPriceEditText.setOnTouchListener(mTouchListener);
    mQuantityEditText.setOnTouchListener(mTouchListener);
    mSupplierEditText.setOnTouchListener(mTouchListener);
    mMailEditText.setOnTouchListener(mTouchListener);
    mIncreaseQuantityButton.setOnTouchListener(mTouchListener);
    mDecreaseQuantityButton.setOnTouchListener(mTouchListener);
    mSelectImageButton.setOnTouchListener(mTouchListener);
    mOrderButton.setOnTouchListener(mTouchListener);
}

private void initialiseViews() {
        mOrderButton = (Button) findViewById(R.id.order_button);
            mOrderButton.setVisibility(View.VISIBLE);
            mOrderButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    String productName = mNameEditText.getText().toString().trim();
                    String emailAddress = "mailto:" + mMailEditText.getText().toString().trim();
                    String subjectHeader = "Order For: " + productName;
                    String orderMessage = "Please send a unit of " + productName + ". " + " \n\n" + "Thank you.";
                    Intent intent = new Intent(Intent.ACTION_SEND);
                    intent.setData(Uri.parse(emailAddress));
                    intent.setType("text/plain");
                    intent.putExtra(Intent.EXTRA_TEXT, orderMessage);
                    intent.putExtra(Intent.EXTRA_SUBJECT, subjectHeader);
                    startActivity(Intent.createChooser(intent, "Send Mail..."));
                    if (intent.resolveActivity(getPackageManager()) != null) {
                        startActivity(intent);
                    }
                }
            });




    mNameEditText = (EditText) findViewById(R.id.edit_name);
    mPriceEditText = (EditText) findViewById(R.id.edit_price);
    mQuantityEditText = (EditText) findViewById(R.id.edit_quantity);
    mSupplierEditText = (EditText) findViewById(R.id.edit_supplier);
    mMailEditText= (EditText) findViewById(R.id.edit_supplier_mail);

        mIncreaseQuantityButton = (Button) findViewById(R.id.editor_increase);
        mIncreaseQuantityButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String quanititynumber = mQuantityEditText.getText().toString();
                if (TextUtils.isEmpty(quanititynumber)) {

                    Toast.makeText(EditorActivity.this, "Quantity field is Empty", Toast.LENGTH_SHORT).show();
                    return;
                } else {
                    mProductQuantity = Integer.parseInt(quanititynumber);

                    mProductQuantity++;
                mQuantityEditText.setText(String.valueOf(mProductQuantity));
            }}
        });

        mDecreaseQuantityButton = (Button) findViewById(R.id.editor_decrease);
        mDecreaseQuantityButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String quanititynumber = mQuantityEditText.getText().toString();

                if (TextUtils.isEmpty(quanititynumber)) {

                    Toast.makeText(EditorActivity.this, "Quantity field is Empty", Toast.LENGTH_SHORT).show();
                    return;
                } else {
                    mProductQuantity = Integer.parseInt(quanititynumber);

                    if (mProductQuantity > 0) {
                    mProductQuantity--;
                    mQuantityEditText.setText(String.valueOf(mProductQuantity));
                }
            }}
        });

        mProductImageView = (ImageView) findViewById(R.id.image);
        mSelectImageButton = (Button) findViewById(R.id.upload_image);
        mSelectImageButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Intent openPictureGallery = new Intent(Intent.ACTION_OPEN_DOCUMENT);

                File pictureDirectory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);

                String pictureDirectoryPath = pictureDirectory.getPath();

                Uri data = Uri.parse(pictureDirectoryPath);

                openPictureGallery.setDataAndType(data, "image/*");

                startActivityForResult(openPictureGallery, PICTURE_GALLERY_REQUEST);
                }

        });
}


@Override
public void onActivityResult(int requestCode, int resultCode, Intent resultData) {
    // checking if the request code and result code match our request
    if (requestCode == PICTURE_GALLERY_REQUEST && resultCode == Activity.RESULT_OK) {
        if (resultData != null) {
            try {
                //this is the address of the image on the sd cards
                mPictureUri = resultData.getData();
                int takeFlags = resultData.getFlags();
                takeFlags &= (Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);

                picturePath = mPictureUri.toString();
                try {
                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                        getContentResolver().takePersistableUriPermission(mPictureUri, takeFlags);
                    }
                } catch (SecurityException e) {
                    e.printStackTrace();
                }
                mProductImageView.setImageBitmap(getBitmapFromUri(mPictureUri, mContext, mProductImageView));

            } catch (Exception e) {
                e.printStackTrace();
                //Show the user a Toast mewssage that the Image is not available
                Toast.makeText(EditorActivity.this, "Unable to open image", Toast.LENGTH_LONG).show();
            }
        }
    }
}

public Bitmap getBitmapFromUri(Uri uri, Context mContext, ImageView imageView) {

    if (uri == null || uri.toString().isEmpty())
        return null;

    // Get the dimensions of the View
    int targetW = imageView.getWidth();
    int targetH = imageView.getHeight();

    InputStream input = null;
    try {
        input = this.getContentResolver().openInputStream(uri);

        // Get the dimensions of the bitmap
        BitmapFactory.Options bmOptions = new BitmapFactory.Options();
        bmOptions.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(input, null, bmOptions);
        if (input != null)
            input.close();

        int photoW = bmOptions.outWidth;
        int photoH = bmOptions.outHeight;

        // Determine how much to scale down the image
        int scaleFactor = Math.min(photoW / targetW, photoH / targetH);

        // Decode the image file into a Bitmap sized to fill the View
        bmOptions.inJustDecodeBounds = false;
        bmOptions.inSampleSize = scaleFactor;
        bmOptions.inPurgeable = true;

        input = this.getContentResolver().openInputStream(uri);
        Bitmap bitmap = BitmapFactory.decodeStream(input, null, bmOptions);
        Bitmap.createScaledBitmap(bitmap, 88, 88, false);
        input.close();
        return bitmap;

    } catch (FileNotFoundException fne) {
        Log.e("EditorActivity", "Failed to load image.", fne);
        return null;
    } catch (Exception e) {
        Log.e("EditorActivity", "Failed to load image.", e);
        return null;
    } finally {
        try {
            input.close();
        } catch (IOException ioe) {

        }
    }
}


private void saveProduct() {

    String nameString = mNameEditText.getText().toString().trim();
    String quantityString = mQuantityEditText.getText().toString().trim();
    String priceString = mPriceEditText.getText().toString().trim();
    String supplierString = mSupplierEditText.getText().toString().trim();
    String supplierEmailString = mMailEditText.getText().toString().trim();


    if (mCurrentProductUri == null &&
            TextUtils.isEmpty(nameString) && TextUtils.isEmpty(quantityString) &&
            TextUtils.isEmpty(priceString) && TextUtils.isEmpty(supplierString)&& TextUtils.isEmpty(supplierEmailString)) {
        return;
    }

    int quantity = parseInt(quantityString);
    double price = Double.parseDouble(mPriceEditText.getText().toString().trim());

    ContentValues values = new ContentValues();
    values.put(ProductContract.ProductEntry.COLUMN_PRODUCT_NAME, nameString);
    values.put(ProductContract.ProductEntry.COLUMN_PRODUCT_PRICE, priceString);
    values.put(ProductContract.ProductEntry.COLUMN_PRODUCT_QUANTITY, quantityString);
    values.put(ProductContract.ProductEntry.COLUMN_PRODUCT_SUPPLIER, supplierString);
    values.put(ProductContract.ProductEntry.COLUMN_PRODUCT_SUPPLIER_MAIL, supplierEmailString);

    if(mPictureUri!=null) {
        picturePath = mPictureUri.toString().trim();
    }
    else{
        picturePath=stringUri;
    }

    values.put(ProductContract.ProductEntry.COLUMN_PRODUCT_PICTURE, picturePath);

    if (mCurrentProductUri == null) {

        Uri newUri = getContentResolver().insert(ProductContract.ProductEntry.CONTENT_URI, values);

        if (newUri == null) {
            Toast.makeText(this, getString(R.string.editor_insert_product_failed),
                    Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(this, getString(R.string.editor_insert_product_successful),
                    Toast.LENGTH_SHORT).show();
        }
    } else {
        int rowsAffected = getContentResolver().update(mCurrentProductUri, values, null, null);

        if (rowsAffected == 0) {
            Toast.makeText(this, getString(R.string.editor_update_product_failed),
                    Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(this, getString(R.string.editor_update_product_successful),
                    Toast.LENGTH_SHORT).show();
        }
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_editor, menu);
    return true;
}


@Override
public boolean onPrepareOptionsMenu(Menu menu) {
    super.onPrepareOptionsMenu(menu);
    if (mCurrentProductUri == null) {
        MenuItem menuItem = menu.findItem(R.id.action_delete);
        menuItem.setVisible(false);
    }
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.action_save:
            saveProduct();
            finish();
            return true;
        case R.id.action_delete:
            showDeleteConfirmationDialog();
            return true;
        case android.R.id.home:
            if (!mProductHasChanged) {
                NavUtils.navigateUpFromSameTask(EditorActivity.this);
                return true;
            }


            DialogInterface.OnClickListener discardButtonClickListener =
                    new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            NavUtils.navigateUpFromSameTask(EditorActivity.this);
                        }
                    };

            showUnsavedChangesDialog(discardButtonClickListener);
            return true;
    }
    return super.onOptionsItemSelected(item);
}


@Override
public void onBackPressed() {
    if (!mProductHasChanged) {
        super.onBackPressed();
        return;
    }

    DialogInterface.OnClickListener discardButtonClickListener =
            new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    finish();
                }
            };

    showUnsavedChangesDialog(discardButtonClickListener);
}

@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
    String[] projection = {
            ProductContract.ProductEntry._ID,
            ProductContract.ProductEntry.COLUMN_PRODUCT_NAME,
            ProductContract.ProductEntry.COLUMN_PRODUCT_PRICE,
            ProductContract.ProductEntry.COLUMN_PRODUCT_QUANTITY,
            ProductContract.ProductEntry.COLUMN_PRODUCT_SUPPLIER,
            ProductContract.ProductEntry.COLUMN_PRODUCT_SUPPLIER_MAIL,
            ProductContract.ProductEntry.COLUMN_PRODUCT_PICTURE};

    return new CursorLoader(this,   // Parent activity context
            mCurrentProductUri,         // Query the content URI for the current product
            projection,             // Columns to include in the resulting Cursor
            null,                   // No selection clause
            null,                   // No selection arguments
            null);                  // Default sort order
}

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
    if (cursor == null || cursor.getCount() < 1) {
        return;
    }

    ViewTreeObserver viewTreeObserver = mProductImageView.getViewTreeObserver();
    viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                mProductImageView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                mProductImageView.setImageBitmap(getBitmapFromUri(mPictureUri, mContext, mProductImageView));
            }
        }
    });

    if (cursor.moveToFirst()) {
        int nameColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_NAME);
        int priceColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_PRICE);
        int quantityColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_QUANTITY);
        int supplierColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_SUPPLIER);
        int mailColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_SUPPLIER_MAIL);
        int pictureColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_PICTURE);

        String name = cursor.getString(nameColumnIndex);
        String price = cursor.getString(priceColumnIndex);
        int quantity = cursor.getInt(quantityColumnIndex);
        String supplier = cursor.getString(supplierColumnIndex);
        String mail = cursor.getString(mailColumnIndex);
        stringUri = cursor.getString(pictureColumnIndex);

        Uri uriData = Uri.parse(stringUri);


        mNameEditText.setText(name);
        mPriceEditText.setText(price);
        mQuantityEditText.setText(String.valueOf(quantity));
        mSupplierEditText.setText(supplier);
        mMailEditText.setText(mail);
        if (mPictureUri!=null){
            if (stringUri!=null)
            mProductImageView.setImageURI(uriData);
        else {
            Bitmap bM = getBitmapFromUri(mPictureUri, mContext, mProductImageView);
            mProductImageView.setImageBitmap(bM);
        }}

    }
}

@Override
public void onLoaderReset(Loader<Cursor> loader) {
    mNameEditText.setText("");
    mPriceEditText.setText("");
    mQuantityEditText.setText("");
    mSupplierEditText.setText("");
    mMailEditText.setText("");
    mProductImageView.setImageResource(R.drawable.ic_add_a_photo_black_24dp);
}


private void showUnsavedChangesDialog(
        DialogInterface.OnClickListener discardButtonClickListener) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage(R.string.unsaved_changes_dialog_msg);
    builder.setPositiveButton(R.string.discard, discardButtonClickListener);
    builder.setNegativeButton(R.string.keep_editing, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            if (dialog != null) {
                dialog.dismiss();
            }
        }
    });

    AlertDialog alertDialog = builder.create();
    alertDialog.show();
}

private void showDeleteConfirmationDialog() {

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage(R.string.delete_dialog_msg);
    builder.setPositiveButton(R.string.delete, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            deleteProduct();
        }
    });
    builder.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
            if (dialog != null) {
                dialog.dismiss();
            }
        }
    });

    AlertDialog alertDialog = builder.create();
    alertDialog.show();
}


private void deleteProduct() {
    if (mCurrentProductUri != null) {
        int rowsDeleted = getContentResolver().delete(mCurrentProductUri, null, null);

        if (rowsDeleted == 0) {
            Toast.makeText(this, getString(R.string.editor_delete_product_failed),
                    Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(this, getString(R.string.editor_delete_product_successful),
                    Toast.LENGTH_SHORT).show();
        }
    }

    finish();
}
}

完整代码的链接是:https://drive.google.com/open?id=1aQFcWHinIqqXHbTyssfPYTD20o9E2piA 如果您在这里找不到 java 文件，它们是:https://drive.google.com/drive/folders/1VKp0CoJlJssSdKzK4ctk26KFY0_xIDzU?usp=sharing

Answer 1

在您的 onLoadFinished 中，您假设 mPictureURI 已设置且不为空。 现在您已经在 mProductImageView 上设置了一个用于更改的监听器。无论您在 mProductImageView 下面写/设置什么，最终在监听器中它被设置回 mPictureURI，它是空的，因此显示一个空的图像空间。

请看下面的代码(也验证它有效)。

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
    if (cursor == null || cursor.getCount() < 1) {
        return;
    }

    if (cursor.moveToFirst()) {
        int nameColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_NAME);
        int priceColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_PRICE);
        int quantityColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_QUANTITY);
        int supplierColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_SUPPLIER);
        int mailColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_SUPPLIER_MAIL);
        int pictureColumnIndex = cursor.getColumnIndex(ProductContract.ProductEntry.COLUMN_PRODUCT_PICTURE);

        String name = cursor.getString(nameColumnIndex);
        String price = cursor.getString(priceColumnIndex);
        int quantity = cursor.getInt(quantityColumnIndex);
        String supplier = cursor.getString(supplierColumnIndex);
        String mail = cursor.getString(mailColumnIndex);
        stringUri = cursor.getString(pictureColumnIndex);

        mPictureUri = Uri.parse(stringUri);


        mNameEditText.setText(name);
        mPriceEditText.setText(price);
        mQuantityEditText.setText(String.valueOf(quantity));
        mSupplierEditText.setText(supplier);
        mMailEditText.setText(mail);
    }

    ViewTreeObserver viewTreeObserver = mProductImageView.getViewTreeObserver();
    viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                mProductImageView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                if(mPictureUri !=null) {
                    mProductImageView.setImageBitmap(getBitmapFromUri(mPictureUri, mContext, mProductImageView));
                }
            }
        }
    });
}