在 C# 中从 Access 数据库存储和检索图像

Question

我是 C# 编程的新手，我正在尝试创建一个软件，允许用户将信息和图片保存到 Ms 访问数据库中。我遵循了 youtube 上的教程并设法存储了我需要的信息和图片，但我似乎无法检索图像并将其显示在图片框中。谁能帮帮我？

我的代码是：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;
using System.IO;

namespace ConnectionApp
{
    public partial class ClinicaPrivada : Form
    {
        OleDbConnection DBConnection = new OleDbConnection();
        OleDbDataAdapter DataAdapter;
        DataTable LocalDatatable = new DataTable();
        int rowPosition = 0;
        int rowNumber = 0;


        public ClinicaPrivada()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            ConnectToDatabase();     
        }
        public void ConnectToDatabase()
        {
            DBConnection.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=ClinicaPrivada.mdb";
            DataAdapter = new OleDbDataAdapter("Select * From Pacientes", DBConnection);
            DataAdapter.Fill(LocalDatatable);
            if (LocalDatatable.Rows.Count != 0)
            {
                rowPosition = LocalDatatable.Rows.Count;
            }
        }

        public void RefreshDBConnection()
        {
            if (DBConnection.State.Equals(ConnectionState.Open))
            {
                DBConnection.Close();
                LocalDatatable.Clear();
                ConnectToDatabase();
            }
        }
        private void btnBrowse_Click(object sender, EventArgs e)
        {

        }

        public byte[] ConvertAndStoreToDB(Image InputImage)
        {
            Bitmap BmpImage = new Bitmap(InputImage);
            MemoryStream Mystream = new MemoryStream();
            BmpImage.Save(Mystream, System.Drawing.Imaging.ImageFormat.Jpeg);
            byte[] ImageAsBytes = Mystream.ToArray();
            return ImageAsBytes;
        }
        public void StoreToDB(byte[] ImageAsBytes)
        {
            string NrDoPaciente;
            NrDoPaciente = Convert.ToString(txtNrdoPaciente.Text);
            string Empresa;
            Empresa = Convert.ToString(txtEmpresa.Text);
            string DataDaConsutla;
            DataDaConsutla = Convert.ToString(txtDatadaConsulta.Text);
            if (DBConnection.State.Equals(ConnectionState.Closed))
                DBConnection.Open();
            try
            {
                MessageBox.Show("Saving Image at index:" + rowPosition.ToString());
                OleDbCommand insert = new OleDbCommand("Insert Into Pacientes (NrDoPaciente, Empresa, DatadaConsulta, Document) VALUES('" + NrDoPaciente +"','" + Empresa + "','" + DataDaConsutla + "','" + "Document"  + "')" , DBConnection);
                OleDbParameter InsertParameter = insert.Parameters.AddWithValue("Docu", SqlDbType.Binary);
                int rowsAffected = insert.ExecuteNonQuery();
                MessageBox.Show("Data Stored successfully in " + rowsAffected.ToString() + "Row");
                rowPosition++;

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message.ToString());
                MessageBox.Show(ex.StackTrace.ToString());
            }
            finally
            {
                RefreshDBConnection();
            }

        }
        private Image ReadImageFromDB()
        {
            Image FetchedImg;

            if (rowNumber >= 0)
            {

                byte[] FetchedImgBytes = (byte[])LocalDatatable.Rows[rowNumber]["Document"];
                MemoryStream stream = new MemoryStream(FetchedImgBytes);
                FetchedImg = Image.FromStream(stream);
                return FetchedImg;
            }
            else
            {
                MessageBox.Show("There are no Images in the database yet. Please reconnect or add some images.");
                return null;
            }
        }

        private void btnBrowse_Click_1(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                pictureBox1.Image = Image.FromFile(openFileDialog1.FileName);

            }

        }

        private void btnSave_Click_1(object sender, EventArgs e)
        {
            StoreToDB(ConvertAndStoreToDB(pictureBox1.Image));
        }

        private void btnDisplayAll_Click(object sender, EventArgs e)
        {
            RefreshDBConnection();

            rowNumber = 0;
            pictureBox2.Image = ReadImageFromDB();
            btnNext.Enabled = true;
            BtnPrevious.Enabled = true; 

        }





    }

}

Answer 1

创建数据表，如： 桌子： Id int，图像 OLE 对象

然后使用此代码插入

//Convert img into bytes
byte[] FileBytes = null;
string imgpath = "PatientsPhotos/" + lbl_patientID.Content.ToString() + ".jpg";
FileStream fs = new FileStream(imgpath,System.IO.FileMode.Open,System.IO.FileAccess.Read);
BinaryReader BR = new BinaryReader(fs);
long allbytes = new FileInfo(imgpath).Length;
FileBytes = BR.ReadBytes((Int32)allbytes);
patient.imagepath = FileBytes;

然后，将“imagepath”插入到图片位置表中

并从表中检索图像路径并转换为如下图像：

ImageSourceConverter imgConv = new ImageSourceConverter();
string path = ("PatientsPhotos/" + this.pt_id + ".jpg");
ImageSource imageSource = (ImageSource)imgConv.ConvertFromString(path);
imgVideo.Source = imageSource;

我认为这可能会对您有所帮助。谢谢

Answer 2

您在内存中的图像可能超出范围。 This question 直接相关，如果我没记错的话。

您必须制作图像的副本。否则，您的图像将链接到创建它的对象，当该对象超出范围时，您的图像数据就会丢失。

我希望您正在尝试执行的操作中遇到异常。

顺便说一句，我同意建议避免使用 MS Access 的评论者。有更好的免费选项可供您使用。