用C＃插入图像哈希 [英] Image Hash inserting in C#

问题描述

<$>当我上传图像哈希也生成与该图像我存储图像中的数据库，但问题是我如何将哈希存储在database.Below是我的代码。 p $ p $ private void FirstpictureBox_Click（object sender，EventArgs e）
{
OpenFileDialog ofd = new OpenFileDialog（）;
ofd.Title =选择第一张图片;
ofd.Filter =Image File（*。png; *。jpg; *。bmp; *。gif）| * .png; *。jpg; *。bmp; *。gif;
if（ofd.ShowDialog（）== DialogResult.OK）
{
FirstpictureBox.Image = new Bitmap（ofd.FileName）;
byte [] imgBytes = new byte [0];

//将图像转换为字节数组
imgBytes =（byte []）converter.ConvertTo（FirstpictureBox.Image，imgBytes.GetType（））;

//从图像字节计算SHA哈希字符串
string hash = ComputeHashCode（imgBytes）;


私有字符串ComputeHashCode（byte [] imgBytes）
{
//计算散列字节
byte [] hash = shaEncryptor.ComputeHash（ imgBytes）;

//将散列字节转换为字符串表示形式
返回Convert.ToBase64String（hash）;


$ b public void ImageHash（string hash）
{

}
private void SaveRecord（）
{
ImageHash（hash）;
字符串connString = ConfigurationManager.ConnectionStrings [dbx]。ConnectionString;
string cmdString =INSERT INTO users（img1，hash）VALUES（@ firstimage，@ hash）;
using（OleDbConnection con = new OleDbConnection（connString））
{
using（OleDbCommand cmd = new OleDbCommand（cmdString，con））
{
con.Open（ ）;
cmd.Parameters.AddWithValue（@ firstimage，savePhoto（））;
cmd.Parameters.AddWithValue（@ hash，hash）;
cmd.ExecuteNonQuery（）;



$ b

当我在SaveRecord（）函数中调用ImageHash（hash）函数，它给了我一个error.hash在当前context.how中不存在，我可以修复这个问题。

解决方案

在类级别声明您的 hash 变量（也就是说，在任何函数或方法之外）。

现在，您已经在函数/方法级别声明了字符串，这意味着只有 FirstpictureBox_Click（） 将可以访问它。

 字符串散列;只需将该声明移出该方法即可。 
 $ b $ private void FirstpictureBox_Click（object sender，EventArgs e）
 {
 ...您的代码... 
 hash = ComputeHashCode（imgBytes）; 
} 
  

When i upload an image hash is also generated with that image i store image in db but problem is how can i store hash in database.Below is my code.

private void FirstpictureBox_Click(object sender, EventArgs e)
        {
        OpenFileDialog ofd = new OpenFileDialog();
        ofd.Title = "Select First Image";
        ofd.Filter = "Image File(*.png;*.jpg;*.bmp;*.gif)|*.png;*.jpg;*.bmp;*.gif";
        if (ofd.ShowDialog() == DialogResult.OK)
            {
            FirstpictureBox.Image = new Bitmap(ofd.FileName);
            byte[] imgBytes = new byte[0];

            //convert image to byte array
            imgBytes = (byte[])converter.ConvertTo(FirstpictureBox.Image, imgBytes.GetType());

            //compute SHA hash string from image bytes
            string hash = ComputeHashCode(imgBytes);
            }
        }
private string ComputeHashCode(byte[] imgBytes)
    {
        //Compute hash bytes
        byte[] hash = shaEncryptor.ComputeHash(imgBytes);

        //Convert hash bytes to string representation
        return Convert.ToBase64String(hash);

    }

    public void ImageHash(string hash)
    {

    }
private void SaveRecord()
        {
            ImageHash(hash);
        string connString = ConfigurationManager.ConnectionStrings["dbx"].ConnectionString;
        string cmdString = "INSERT INTO users (img1,hash) VALUES (@firstimage,@hash)";
        using (OleDbConnection con = new OleDbConnection(connString))
            {
            using (OleDbCommand cmd = new OleDbCommand(cmdString, con))
                {
                con.Open();
                cmd.Parameters.AddWithValue("@firstimage", savePhoto());
                cmd.Parameters.AddWithValue("@hash", hash);
                cmd.ExecuteNonQuery();
                }
            }

        }

When i call ImageHash(hash) function in SaveRecord() function it give me an error.hash doesn't exist in current context.how can i fix this problem.

解决方案

Declare your hash variable at class level instead (that is, outside any function or method).

As it is now, you have declared the string at function/method level, which means only FirstpictureBox_Click() will have access to it. Just move the declaration out of the method and you are good to go.

string hash;

private void FirstpictureBox_Click(object sender, EventArgs e)
{
    ...your code...
    hash = ComputeHashCode(imgBytes);
}

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