error-参数无效. [英] error-Parameter is not valid.

问题描述

你好朋友，

我尝试使用以下代码从访问数据库中检索图像:

Hello friends,

I try to retrieve an image from access database using following code:

private void button3_Click(object sender, EventArgs e)
{
  OleDbConnection cn = new OleDbConnection(strCn);
  cn.Open();
  OleDbCommand cmd = new OleDbCommand("SELECT Iname,Oimage FROM [Image]", cn);
  OleDbDataAdapter da = new OleDbDataAdapter(cmd);
  DataSet ds = new DataSet();
  da.Fill(ds, "Image");
  int c = ds.Tables["Image"].Rows.Count;
  if (c > 0)
  {
    Byte[] byteOimage = new Byte[0];
    byteOimage = System.Text.Encoding.Unicode.GetBytes((ds.Tables["Image"].Rows[c - 1]["Oimage"]).ToString());
    MemoryStream strOimage = new MemoryStream(byteOimage);
    pictureBox1.Image = Image.FromStream(strOimage);//here i got error message Parameter is not valid.
  }
  cn.Close();
}

我在代码的最后到第二行中提到我遇到了错误.
那我该怎么解决呢?

请帮帮我.

预先感谢.

I mention in the last to second line of my code that I get the error.
So,how can I solve it?

Please help me.

Thanks in advance.

推荐答案

您正尝试使用零长度的字节数组，其中没有任何内容

You are trying to use a zero length byte array, there is nothing in it

Byte[] byteOimage = new Byte[0];

C#相册查看器 [
顺便说一句，匈牙利表示法(byteOimage，strOimage)几年来都没有使用过.

C# Photo Album Viewer[^]

Look at the Display the image section. Although it is SQL Server, the same techniques should work with Access.

BTW, Hungarian notation (byteOimage, strOimage) hasn''t bee used in years.

我也面临以下相同的问题和解决方案:-

I too faced the same issue and solution given below :-

OleDbConnection cn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\rmaheswari\Documents\TestImage.accdb;Persist Security Info=False;"); 
            cn.Open();  OleDbCommand cmd = new OleDbCommand("SELECT Iname,Oimage FROM [Table1]", cn); 
            OleDbDataAdapter da = new OleDbDataAdapter(cmd);  
            DataSet ds = new DataSet();  da.Fill(ds, "Image");  
            int c = ds.Tables["Image"].Rows.Count;  if (c > 0)
            {
                byte[] rawData = (byte[])ds.Tables["Image"].Rows[c - 1]["Oimage"];
                MemoryStream ms = new MemoryStream();
                Bitmap bm;
                ms.Write(rawData, 78, rawData.Length - 78);
                bm = new Bitmap(ms);
                pictureBox1.Image = bm;
               
            }  cn.Close();}

这是您的问题代码:

This is your problem code:

byteOimage = System.Text.Encoding.Unicode.GetBytes((ds.Tables["Image"].Rows[c - 1]["Oimage"]).ToString());

Access将数据存储为字节数组.但是，然后您将该字节数组转换为字符串.

单步执行代码，并在该行上放置一个断点.然后，添加手表ds.Tables["Image"].Rows[c - 1]["0image"]).ToString()并查看其内容.

只需摆脱该行上的ToString()即可.您可能还需要像其他答案一样键入强制转换.

Access stores the data as a byte array. But then you take that byte array and convert it to a string.

Step through your code and put a breakpoint in at that line. Then, add a watch for ds.Tables["Image"].Rows[c - 1]["0image"]).ToString() and see what it says.

Just get rid of the ToString() on that line. You may also have to type cast it as in the other answer.

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