Question

我正在尝试至少两个小时才能解决这个问题我正在检索存储在数据库中的图像。

public Image Base64ToImage(string base64String) {
    // Convert Base64 String to byte[]
    byte[] imageBytes = Convert.FromBase64String(base64String);
    MemoryStream ms = new MemoryStream(imageBytes, 0, imageBytes.Length);
    // Convert byte[] to Image
    ms.Write(imageBytes, 0, imageBytes.Length);
    Image image = Image.FromStream(ms, true);
    return image;
}

使用数据库的代码为：

con.Open();
cmd = new SqlCommand("select [s_image] from [2017] where serialno="+serianotext.Text ,con);
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read()) {

    imagepicturebox.Image = Base64ToImage(dr[0].ToString());
}
con.Close();

错误显示在图片中

Answer 1

我不知道你的base64字符串的值，所以我写了这个例子。您可以使用它来制作自己的代码。

using System;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;

namespace ConsoleApplication2
{
    class Program
    {
        private static string connectionString = "Data Source=localhost;Initial Catalog=my_test_db;Integrated Security=True;";

        public static string ImageToBase64(Image image, ImageFormat imageFormat)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                image.Save(ms, imageFormat);
                byte[] imageBytes = ms.ToArray();
                string base64String = Convert.ToBase64String(imageBytes);
                return base64String;
            }
        }
        public static Image Base64ToImage(string base64String)
        {
            byte[] imageBytes = Convert.FromBase64String(base64String);
            using (MemoryStream ms = new MemoryStream(imageBytes, 0, imageBytes.Length))
            {
                ms.Write(imageBytes, 0, imageBytes.Length);
                Image image = Image.FromStream(ms, true);
                return image;
            }
        }

        static void Main(string[] args)
        {
            string image1base64;

            using(Bitmap image1 = (Bitmap) Image.FromFile("C:\\test1.png"))
                image1base64 = ImageToBase64((Image)image1, ImageFormat.Png);

            using (SqlConnection sqlConnection = new SqlConnection(connectionString))
            {
                sqlConnection.Open();

                using (SqlCommand sqlCommand = new SqlCommand("create table #base64test(id int not null, base64image varchar(max));", sqlConnection))
                    sqlCommand.ExecuteNonQuery();

                using (SqlCommand sqlCommand = new SqlCommand("insert #base64test(id, base64image) values(@id, @base64image)", sqlConnection))
                {
                    sqlCommand.Parameters.Add("@id", SqlDbType.Int);
                    sqlCommand.Parameters["@id"].Value = 1;

                    sqlCommand.Parameters.Add("@base64image", SqlDbType.VarChar, -1);
                    sqlCommand.Parameters["@base64image"].Value = image1base64;

                    sqlCommand.ExecuteNonQuery();
                }

                using (SqlCommand sqlCommand = new SqlCommand("select base64image from #base64test where id = @id", sqlConnection))
                {
                    sqlCommand.Parameters.Add("@id", SqlDbType.Int);
                    sqlCommand.Parameters["@id"].Value = 1;

                    using (SqlDataReader rd = sqlCommand.ExecuteReader(CommandBehavior.SequentialAccess))
                    {
                        if (rd.Read() == false)
                            throw new ApplicationException("An error occurred ...");

                        object[] temp = new object[rd.FieldCount];//[1]

                        // read BLOB trick
                        if (rd.GetSqlValues(temp) != rd.FieldCount)
                            throw new ApplicationException("An error occurred ...");

                        Image image2 = Base64ToImage(((SqlString)temp[0]).ToString());
                        image2.Save("C:\\test2.png", ImageFormat.Png);
                    }
                }
            }
        }
    }
}

图像未检索并显示错误输入不是有效的Base 64字符串

1 个答案: