如何使用sqlite数据库上传和检索图像 [英] How to upload and retrieve image using sqlite databse

问题描述

我的问题在Xamarin中.使用SQLite数据库的表单可以上传图像并将其检索到相同的位置(例如个人资料图片).

My question is in Xamarin.Forms using the SQLite database can upload an image and retrieve it to the same place(like a profile picture).

我通过google浏览，但是我找不到像这样的东西，这可以在使用SQLite本地数据库的xamarin.Forms中完成

I look through google but I couldn't find anything like this is this possible to do in xamarin.Forms using SQLite local database

推荐答案

是的.观看这个小例子:

Yes it's possible. Watch this little example:

只需将图像转换为字节数组，即可使用:

Just convert your image to a byte array, you can use:

byte[] myimage = System.IO.File.ReadAllBytes("pathtoimage")

将图像插入到sql lite db中:

insert the image into your sql lite db:

public bool InsertMessage()
{

    SqliteCommand cmd = new SqliteCommand(con);

        cmd.CommandText = "INSERT INTO Images(Data) VALUES (@img)";
        cmd.Prepare();

        cmd.Parameters.Add("@img", DbType.Binary, myimage.Length);
        cmd.Parameters["@img"].Value = myimage;
        cmd.ExecuteNonQuery();

        con.Close();
}

检索图像并将其存储到文件中:

to retrive the image and store it to a file:

 using(SqliteConnection con = new SqliteConnection(cs))
        {            
            con.Open();

            SqliteCommand cmd = new SqliteCommand(con);   
            cmd.CommandText = "SELECT Data FROM Images WHERE Id=1";
            byte[] data = (byte[]) cmd.ExecuteScalar();

            try
            {               
                if (data != null)
                { 
                    File.WriteAllBytes("woman2.jpg", data);
                    myimage = data
                } else 
                {
                    Console.WriteLine("Binary data not read");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }            

            con.Close();
        }

如果要将图像保存到位图变量中:

if you want save the image into a bitmap var:

ByteArrayInputStream inputStream = new ByteArrayInputStream(myimage);
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);

这篇关于如何使用sqlite数据库上传和检索图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！