将文件转换为字节数组，保存在 Access-DB 中，从 DB 读取并创建文件

debugcn 发表于 Dev

用户7220101

你好，

我正在努力

将文件转换为字节[]
在 Access 数据库中写入 byte[]
从数据库读取字节[]
从中重新创建文件

byte[] bytes = System.IO.File.ReadAllBytes(@"C:\Users\user\Docs\1.pdf");

AccessConnector.WriteByteArrayToID(122, bytes);

    public static void WriteByteArrayToID(int aID, byte[] aFile)
    {
        conn.Open();
        dbCommand = new OleDbCommand("UPDATE Belege SET Datei = @file WHERE(ID = @ID)", conn);

        dbCommand.Parameters.Add("@ID", OleDbType.Integer).Value = aID;
        dbCommand.Parameters.Add("@file", OleDbType.VarBinary).Value = aFile.ToString();

        dbDataAdapter = new OleDbDataAdapter(dbCommand);
        dbCommand.ExecuteNonQuery();

        conn.Close();
    }

        DataTable table = AccessConnector.GetFileByteArrayByID(122);
        DataRow row = table.Rows[0];

        System.Text.UTF8Encoding enc = new System.Text.UTF8Encoding();

        byte[] newbytes = enc.GetBytes(row.ItemArray[0].ToString());

            System.IO.File.WriteAllBytes(@"C:\Users\user\Documents\Docs\a.pdf", newbytes);

问题是， newbytes 比字节小得多，并且新文件不可访问。在 Access DB 单元格中，就像中文字母一样。我已经尝试使用其他编码。没有什么。任何人都可以解释为什么它小得多（23000 个字符到 400 个字符）。谢谢。

更新为其他功能添加了代码

    public static DataTable GetFileByteArrayByID(int aID)
    {
        conn.Open();

        dbCommand = new OleDbCommand("SELECT Datei FROM Belege WHERE (ID = @ID)", conn);

        dbCommand.Parameters.Add("@ID", OleDbType.Integer).Value = aID;
        dbDataAdapter = new OleDbDataAdapter(dbCommand);
        DataTable resultDataTable = new DataTable();
        dbDataAdapter.Fill(resultDataTable);

        conn.Close();
        return resultDataTable;
    }

用户7220101

解决方案

    public static void WriteByteArrayToID(int aID, byte[] aFile)
    {
        conn.Open();

        dbCommand = new OleDbCommand("UPDATE Belege SET Datei = @file WHERE(ID = @ID)", conn);

        string tmp = Convert.ToBase64String(aFile);

        dbCommand.Parameters.Add("@file", OleDbType.VarChar).Value = tmp;
        dbCommand.Parameters.Add("@ID", OleDbType.Integer).Value = aID;

        dbDataAdapter = new OleDbDataAdapter(dbCommand);
        dbCommand.ExecuteNonQuery();

        conn.Close();
    }

    public static DataTable GetFileByteArrayByID(int aID)
    {
        conn.Open();

        dbCommand = new OleDbCommand("SELECT Datei FROM Belege WHERE (ID = @ID)", conn);

        dbCommand.Parameters.Add("@ID", OleDbType.Integer).Value = aID;
        dbDataAdapter = new OleDbDataAdapter(dbCommand);
        DataTable resultDataTable = new DataTable();
        dbDataAdapter.Fill(resultDataTable);

        conn.Close();
        return resultDataTable;
    } 

        //-----------------------------------------------------------------------------------------------------------------

        byte[] bytes = System.IO.File.ReadAllBytes(@"C:\Users\user\Music\1.pdf");

        AccessConnector.WriteByteArrayToID(122, bytes);

        DataTable table = AccessConnector.GetFileByteArrayByID(122);

        string file = table.Rows[0][0] as string;

        System.IO.File.WriteAllBytes(@"C:\Users\user\Documents\Dokumente\a.pdf", Convert.FromBase64String(file));

        //-----------------------------------------------------------------------------------------------------------------

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