c# - 从 SQL Server 读取 blob 并显示到图片框

问题描述:

我看过这个网站 使用 C# .NET 从/向 SQL Server 读取/写入 BLOB
从数据库读取 blob 后,它将图像保存到 FileSystem.
我想换.
而不是将图像保存到文件系统,我想将它显示到图片框

i have seen this site Read / Write BLOBs from / to SQL Server using C# .NET
After it reads the blob from database, it is saving the image to FileSystem.
I'd like to change it.
Instead of saving the Image to FileSystem i'd like to display it to the pictureBox

这里是一些关于读取 BLOB 的代码

here are some of its code on reading BLOB

// **** Read BLOB from the Database and save it on the Filesystem
    public void GetEmployee(string plastName,string pfirstName)
    {
        SqlCommand getEmp = new SqlCommand(
            "SELECT EmployeeID, Photo "+
            "FROM Employees "+
            "WHERE LastName = @lastName "+
            "AND FirstName = @firstName", _conn);

        getEmp.Parameters.Add("@LastName",  SqlDbType.NVarChar, 20).Value = plastName;
        getEmp.Parameters.Add("@FirstName", SqlDbType.NVarChar, 10).Value = pfirstName;

        FileStream fs;                          // Writes the BLOB to a file (*.bmp).
        BinaryWriter bw;                        // Streams the BLOB to the FileStream object.
        int bufferSize = 100;                   // Size of the BLOB buffer.
        byte[] outbyte = new byte[bufferSize];  // The BLOB byte[] buffer to be filled by GetBytes.
        long retval;                            // The bytes returned from GetBytes.
        long startIndex = 0;                    // The starting position in the BLOB output.
        string emp_id = "";                     // The employee id to use in the file name.

        // Open the connection and read data into the DataReader.
        _conn.Open();
        SqlDataReader myReader = getEmp.ExecuteReader(CommandBehavior.SequentialAccess);

        while (myReader.Read())
        {
            // Get the employee id, which must occur before getting the employee.
            emp_id = myReader.GetInt32(0).ToString();

            // Create a file to hold the output.
            fs = new FileStream("employee" + emp_id + ".bmp",
                                FileMode.OpenOrCreate, FileAccess.Write);
            bw = new BinaryWriter(fs);

            // Reset the starting byte for the new BLOB.
            startIndex = 0;

            // Read the bytes into outbyte[] and retain the number of bytes returned.
            retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize);

            // Continue reading and writing while there are bytes beyond the size of the buffer.
            while (retval == bufferSize)
            {
                bw.Write(outbyte);
                bw.Flush();

                // Reposition the start index to the end of the last buffer and fill the buffer.
                startIndex += bufferSize;
                retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize);
            }

            // Write the remaining buffer.
            bw.Write(outbyte, 0, (int)retval);
            bw.Flush();

            // Close the output file.
            bw.Close();
            fs.Close();
        }

        // Close the reader and the connection.
        myReader.Close();
        _conn.Close();
    }

您认为应该更换什么?请帮我.我刚接触 c#

What do you think should be replaced? please help me. I am just new to c#

您可以使用 MemoryStream 来完成此操作.假设 blob 是由 PictureBox 控件支持的正确格式的图像...

You can use MemoryStream to accomplish this. Assuming that the blob is a properly formed image which is supported by the PictureBox control...

    MemoryStream memoryStream = new MemoryStream(outbyte);
    pictureBox.Image = Image.FromStream(memoryStream);