以下是描述与MySQL连接的链接：
http://www.codeproject.com/KB/aspnet/asp_net_and_mysql.aspx
http://www.codeproject.com/KB/aspnet/image_asp.aspx
以下是从mysql数据库显示图像的代码：
protected void Page_Load(object sender, EventArgs e)
{
MySqlConnection conn = new MySqlConnection(db);
conn.Open();
string s;
s = Session["t"].ToString();
string commantext = "select img_id,img_file,img_type,img_name from image where img_name='"+s+"'";
// string commantext = "select img_id,img_file,img_type,img_name from image";
// DataSet ds = MySqlHelper.ExecuteDataset(conn, commantext);
MySqlCommand cmd = new MySqlCommand(commantext,conn);
cmd.Parameters.Add("?img_id", MySqlDbType.Int32).Value = s;
// DataTable dt = ds.Tables[0];
DataTable dt = GetData(cmd);
while(dt !=null)
{
Byte[] bytes = (Byte[])dt.Rows[0]["img_file"];
// Byte[] bytes = (Byte[])dt.Rows[1][] ;
Response.Buffer = true;
Response.Charset = "";
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.ContentType = dt.Rows[0]["img_type"].ToString();
Response.AddHeader("content-disposition", "attachment;filename="
+ dt.Rows[0]["img_name"].ToString());
Response.BinaryWrite(bytes);
Response.Flush();
Response.End();
}
conn.Close();
}
private DataTable GetData(MySqlCommand cmd)
{
DataTable dt = new DataTable();
//String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
MySqlConnection con = new MySqlConnection(db);
MySqlDataAdapter sda = new MySqlDataAdapter();
cmd.CommandType = CommandType.Text;
cmd.Connection = con;
try
{
con.Open();
sda.SelectCommand = cmd;
sda.Fill(dt);
return dt;
}
catch
{ return null;
}
finally
{ con.Close();
sda.Dispose();
con.Dispose();
}
}
我将图像文件上传到mysql数据库的代码如下。
protected void Button1_Click（object sender，EventArgs e） { 流img_strm = File1.PostedFile.InputStream;
int img_len = File1.PostedFile.ContentLength;
string strtype = File1.PostedFile.ContentType;
//code snippet to determine image height and width.
System.Drawing.Image i = System.Drawing.Image.FromStream(img_strm);
int fileheight = int.Parse(i.Width.ToString());
int filewidth = int.Parse(i.Height.ToString());
strname = Text1.Value;
//Session["t"] = strname;
byte[] imgData = new byte[img_len];
int n = img_strm.Read(imgData, 0, img_len);
int result = saveToDb(strname, imgData, strtype);
}
private int saveToDb(string imgName, byte[] imgbin, string imgContenttype)
{
string db = "server=localhost;database=test;uid=root;password=techsoft";
MySqlConnection conn = new MySqlConnection(db);
MySqlCommand cmd = new MySqlCommand("insert into image(img_name,img_file,img_type) values(?img_name,?img_file,?img_type)", conn);
//MySqlParameter param0 = new MySqlParameter("?img_id", MySqlDbType.Int16, 20);
//param0.Value = ;
//cmd.Parameters.Add(param0);
MySqlParameter param0 = new MySqlParameter("?img_name", MySqlDbType.VarChar, 45);
param0.Value = imgName;
cmd.Parameters.Add(param0);
// MySqlParameter param1 = new MySqlParameter("?img_file", MySqlDbType.VarChar, 45);
MySqlParameter param1 = new MySqlParameter("?img_file", MySqlDbType.LongBlob, 10);
param1.Value = imgbin;
cmd.Parameters.Add(param1);
MySqlParameter param2 = new MySqlParameter("?img_type", MySqlDbType.VarChar, 45);
param2.Value = imgContenttype;
cmd.Parameters.Add(param2);
conn.Open();
int num = cmd.ExecuteNonQuery();
conn.Close();
return num;
}
我使用二进制编写器来显示。任何人都可以建议如何以固定尺寸显示图像吗？
答案 0 :(得分：0)
或
答案 1 :(得分：0)
假设您唯一的挑战是仅缩放图像（在上传之前或检索图像时）...这里是一些代码，用于获取图像的缩放尺寸（以适应特定的固定尺寸）...您可以把它放在成像课的某个地方
请注意，有很多方法......
public static Size getScaledDimensions( Image img, Int32 maxW, Int32 maxH)
{
//check if image is already within desired dimensions
if (img.Height <= maxH & img.Width <= maxW)
{
Size orgsize = new Size(img.Width, img.Height);
return orgsize; // no need to rescale
}
else //proceed with rescaling
{
int finalH;
int finalW;
//use height/width ratio to determine our new dimensions
double hwRatio = (double)img.Height / (double)img.Width;
int newW = (int) (maxH/ hwRatio);
int newH = (int) (hwRatio * maxW);
//make sure we scale the right dimension
if (newW <= maxW) // scale width
{
finalH = maxH;
finalW = newW;
}
else
{ // scale height
finalH = newH;
finalW = maxW;
}//end if
Size newsize = new Size(finalW, finalH);
return newsize;
}
答案 2 :(得分：0)
感谢rip和The_AlienCoder提供的所有支持。我找到了自己的问题的答案。
我们需要使用流来转换mysql数据库中的二进制数据。以后的图形库应该用于加载流。与此同时，我们需要根据需要调整图像大小。
protected void Page_Load(object sender, EventArgs e){
//Create connection to mysql database.
MySqlConnection conn = new MySqlConnection(db);
conn.Open();
string s;
s = Session["t"].ToString();
string commantext = "select img_id,img_file,img_type,img_name from image where img_name='"+s+"'";
MySqlCommand cmd = new MySqlCommand(commantext,conn);
cmd.Parameters.Add("?img_id", MySqlDbType.Int32).Value = s;
//create datatable. GetData is a method to fetch the data.
DataTable dt = GetData(cmd);
//Get data from database to bytes.
Byte[] bytes = (Byte[])dt.Rows[0]["img_file"];
//Defining the size to display data.
int outputSize = 100;
if (bytes.Length > 0)
{
// Open a stream for the image and write the bytes into it
System.IO.MemoryStream stream = new System.IO.MemoryStream(bytes, true);
stream.Write(bytes, 0, bytes.Length);
Bitmap bmp = new Bitmap(stream);
Size new_size = new Size();
//resize based on the longer dimension
if (bmp.Width > bmp.Height)
{
new_size.Width = outputSize;
new_size.Height = (int)(((double)outputSize / (double)bmp.Width) * (double)bmp.Height);
}
else
{
new_size.Width = (int)(((double)outputSize / (double)bmp.Height) * (double)bmp.Width);
new_size.Height = outputSize;
}
Bitmap bitmap = new Bitmap(new_size.Width, new_size.Height, bmp.PixelFormat);
Graphics new_g = Graphics.FromImage(bitmap);
new_g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
new_g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
new_g.DrawImage(bmp, -1, -1, bitmap.Width + 1, bitmap.Height + 1);
bmp.Dispose();
bitmap.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
bitmap.Dispose();
new_g.Dispose();
stream.Close();
}
}
private DataTable GetData(MySqlCommand cmd)
{
DataTable dt = new DataTable();
//String strConnString = System.Configuration.ConfigurationManager .ConnectionStrings["conString"].ConnectionString;
MySqlConnection con = new MySqlConnection(db);
MySqlDataAdapter sda = new MySqlDataAdapter();
cmd.CommandType = CommandType.Text;
cmd.Connection = con;
try
{
con.Open();
sda.SelectCommand = cmd;
sda.Fill(dt);
return dt;
}
catch
{ return null;
}
finally
{ con.Close();
sda.Dispose();
con.Dispose();
}
}
}