图片未正确保存到数据库中（作为 BLOB）

发布于 2024-10-26 17:54:41 字数 1221 浏览 1 评论 0 原文

我尝试将图片作为 BLOB 保存到数据库中，但它没有正确存储在数据库中。

传递的 byte[] 是正确的，有 4300 个字符，而在数据库中它只有 12 个字符。这就是数据库中存储的内容： [B@43e7be68

这是我的 SQL_INSERT 的代码：

public boolean SQL_INSERT_PICTURE(PictureDatatype type) {
    try{
        this.db = openHelper.getWritableDatabase();
        Log.d(TAG, "Insert picture");
        System.out.println("insert picture");
        db.execSQL("DELETE FROM picture " +
                "where " + LinkPic + " = '" + type.getLink() + "'");
        db.execSQL("INSERT OR REPLACE INTO picture " +
                "( " + NamePic + ", " + LinkPic + ", " + PicturePic + ") " +
                "VALUES ('" + type.getName() + "', '" + type.getLink() +"', '" + 
                type.getPicture() +"')");

        System.out.println("size of the picture (bytearray): " + type.getPicture().length);
        System.out.println("the picture: " + type.getPicture());
        System.out.println("insert complete");
        db.close();
        return true;
    }
        catch(SQLException s){
            System.out.println("Insert failed");
            db.close();
            return false;
        }
}

我的问题是为什么没有正确的 byte[] 存储在数据库中或者我该怎么做？如果您需要更多信息或代码，请告诉我。

谢谢柯比

原文

I try to save a picture into the database as a BLOB, but its not stored properly in the database.

The byte[] which is passed is correct and has 4300 characters and in the database it just has 12 characters.
That's what is stored in the DB: [B@43e7be68

Here is the code of my SQL_INSERT:

public boolean SQL_INSERT_PICTURE(PictureDatatype type) {
    try{
        this.db = openHelper.getWritableDatabase();
        Log.d(TAG, "Insert picture");
        System.out.println("insert picture");
        db.execSQL("DELETE FROM picture " +
                "where " + LinkPic + " = '" + type.getLink() + "'");
        db.execSQL("INSERT OR REPLACE INTO picture " +
                "( " + NamePic + ", " + LinkPic + ", " + PicturePic + ") " +
                "VALUES ('" + type.getName() + "', '" + type.getLink() +"', '" + 
                type.getPicture() +"')");

        System.out.println("size of the picture (bytearray): " + type.getPicture().length);
        System.out.println("the picture: " + type.getPicture());
        System.out.println("insert complete");
        db.close();
        return true;
    }
        catch(SQLException s){
            System.out.println("Insert failed");
            db.close();
            return false;
        }
}

my question is why isn't the correct byte[] stored in the DB or how can i do it?
If u need more information or code pls tell me.

thx
kirbby

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天煞孤星 2024-11-02 17:54:41

使用此代码将图像转换为可以存储为 BLOB 的 ByteArray：

    private byte[] getBitmapAsByteArray(Bitmap bitmap) {
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        // Middle value is quality, but PNG is lossless, so it's ignored.
        bitmap.compress(CompressFormat.PNG, 0, outputStream);
        return outputStream.toByteArray();
    }

    private byte[] getBitmapAsByteArray(Bitmap bitmap) {
        final int width = bitmap.getWidth();
        final int height = bitmap.getHeight();
        ByteBuffer byteBuffer = ByteBuffer.allocate(width * height * 4);

        bitmap.copyPixelsToBuffer(byteBuffer);
        return byteBuffer.array();
    }

第一个选项应该始终有效。第二个选项假设每像素 32 位（ARGB_8888 格式），因此 4 个字节。如果您的位图是其他格式（例如565），则需要进行一些修改。

当您从数据库读取图像数据时，请执行以下操作：

   public Bitmap loadIcon(long iconId) {
       // Prepare the cursor to read from database....
       byte[] bitmapData = cursor.getBlob(cursor.getColumnIndex(Columns.Icons.DATA));

       return BitmapFactory.decodeByteArray(bitmapData, 0, bitmapData.length);
   }

确保在执行“create table”SQL 语句时将数据库定义为 BLOB。

Use this code to convert the image to a ByteArray that can be stored as a BLOB:

    private byte[] getBitmapAsByteArray(Bitmap bitmap) {
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        // Middle value is quality, but PNG is lossless, so it's ignored.
        bitmap.compress(CompressFormat.PNG, 0, outputStream);
        return outputStream.toByteArray();
    }

    private byte[] getBitmapAsByteArray(Bitmap bitmap) {
        final int width = bitmap.getWidth();
        final int height = bitmap.getHeight();
        ByteBuffer byteBuffer = ByteBuffer.allocate(width * height * 4);

        bitmap.copyPixelsToBuffer(byteBuffer);
        return byteBuffer.array();
    }

First option should always work. Second option assumes 32bits-per-pixel (ARGB_8888 format) thus 4 bytes. if you're bitmap is of another format (e.g 565), it needs some modifications.

When you read the image data from the database, do it like this:

   public Bitmap loadIcon(long iconId) {
       // Prepare the cursor to read from database....
       byte[] bitmapData = cursor.getBlob(cursor.getColumnIndex(Columns.Icons.DATA));

       return BitmapFactory.decodeByteArray(bitmapData, 0, bitmapData.length);
   }

Make sure that the the database is defined as BLOB when you execute your "create table" SQL statement.

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