我正在尝试调整我使用FileUpload控件上传的jpg图像,并将其转换为字节,然后将其保存为数据库(SQL Server 2008)为(varbinary(MAX))。我所做的和下面的代码显示我设法将其转换为字节并作为varbinary(MAX)保存到数据库中。我想知道如何在完成所有这些功能之前调整图像大小。帮帮我吧谢谢!
阅读文件
string filePath = FileUpload1.PostedFile.FileName;
string filename = Path.GetFileName(filePath);
string ext = Path.GetExtension(filename);
根据文件扩展名
设置内容类型string contenttype = String.Empty;
switch (ext)
{
case ".jpg":
contenttype = "image/jpg";
break;
}
转换为字节并使用varbinary
保存到数据库中if (contenttype != String.Empty)
{
Stream fs = FileUpload1.PostedFile.InputStream;
BinaryReader br = new BinaryReader(fs);
Byte[] bytes = br.ReadBytes((Int32)fs.Length);
//insert the file into database
string strQuery = "insert into MemberReport(username, typeofcrime, location, crdatetime, citizenreport, image1, image2, image3, image4, image5)" +
" values ('" + username + "','" + typeofcrime + "','" + location.Trim() + "','" + datetime + "','" + detail.Trim() + "', @Data, @Data2, @Data3, @Data4, @Data5)";
SqlCommand cmd = new SqlCommand(strQuery);
cmd.Parameters.Add("@Data", SqlDbType.Binary).Value = bytes;
cmd.Parameters.Add("@Data2", SqlDbType.Binary).Value = bytes2;
cmd.Parameters.Add("@Data3", SqlDbType.Binary).Value = bytes3;
cmd.Parameters.Add("@Data4", SqlDbType.Binary).Value = bytes4;
cmd.Parameters.Add("@Data5", SqlDbType.Binary).Value = bytes5;
InsertUpdateData(cmd);
lblMessage.ForeColor = System.Drawing.Color.Green;
lblMessage.Text = "Report Sent!";
}
else
{
lblMessage.ForeColor = System.Drawing.Color.Red;
lblMessage.Text = "File format not recognised." +
" Upload Image formats";
}
InsertUpdateData方法
private Boolean InsertUpdateData(SqlCommand cmd)
{
SqlConnection con = new SqlConnection("Data Source=localhost; Initial Catalog=project; Integrated Security=True");
cmd.CommandType = CommandType.Text;
cmd.Connection = con;
try
{
con.Open();
cmd.ExecuteNonQuery();
return true;
}
catch (Exception ex)
{
Response.Write(ex.Message);
return false;
}
finally
{
con.Close();
con.Dispose();
}
答案 0 :(得分:11)
您需要将上传的文件转换为Image
对象,这可以通过以下方式完成:
Image uploaded = Image.FromStream(FileUpload1.PostedFile.InputStream);
接下来,弄清楚你想要的图像有多大。假设您希望最大尺寸为256像素,并保持纵横比。一些代码改编自CodeProject文章Resizing an Image On-The-Fly using .NET:
int originalWidth = uploaded.Width;
int originalHeight = uploaded.Height;
float percentWidth = (float)256 / (float)originalWidth;
float percentHeight = (float)256 / (float)originalHeight;
float percent = percentHeight < percentWidth ? percentHeight : percentWidth;
int newWidth = (int)(originalWidth * percent);
int newHeight = (int)(originalHeight * percent);
现在创建一个新的Bitmap
对象来包含调整大小的图像(来自相同的CodeProject文章)并将原始图像绘制到它:
Image newImage = new Bitmap(newWidth, newHeight);
using (Graphics g = Graphics.FromImage(newImage))
{
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(uploaded, 0, 0, newWidth, newHeight);
}
最后,转换回字节以保存到数据库中:
byte[] results;
using (MemoryStream ms = new MemoryStream())
{
ImageCodecInfo codec = ImageCodecInfo.GetImageEncoders().FirstOrDefault(c => c.FormatID == ImageFormat.Jpeg.Guid);
EncoderParameters jpegParms = new EncoderParameters(1);
jpegParms.Param[0] = new EncoderParameter(Encoder.Quality, 95L);
newImage.Save(ms, codec, jpegParms);
results = ms.ToArray();
}
我采用漫长的路线来设定输出的质量等级。如果您不介意使用什么压缩级别,那么简单的img.Save(ms, ImageFormat.Jpeg);
调用将替换using
代码块中的前4行。
查看我上面提到的CodeProject article,了解有关调整图像大小的更多信息,并阅读C# Image to Byte Array and Byte Array To Image Converter Class(同样在CodeProject上),了解有关将图像转换为字节数组的更多信息。
最后一部分,将图像插入数据库表。我将假设Microsoft SQL,并执行一个非常简单的表插入。
表定义为:
CREATE TABLE [Images](
[ID] [int] IDENTITY(1,1) NOT NULL,
[ImageData] [varbinary](max) NULL,
CONSTRAINT [PK_Images] PRIMARY KEY CLUSTERED
(
[ID] ASC
) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
将图像数据插入表中的代码:
static string connString = "Data Source=localhost; Initial Catalog=project; Integrated Security=True";
public static int InsertImage(byte[] imgdata)
{
using (SqlConnection conn = new SqlConnection(connString))
{
conn.Open();
using (SqlCommand cmd = new SqlCommand("INSERT INTO Images(ImageData) OUTPUT inserted.ID VALUES(@p1)", conn))
{
cmd.Parameters.AddWithValue("@p1", imgdata);
int res = (int)cmd.ExecuteScalar()
return res;
}
}
}
返回值是SQL为记录生成的自动增量值。
或者更新现有图片:
public static void UpdateImage(int id, byte[] imgdata)
{
using (SqlConnection conn = new SqlConnection(connString))
{
conn.Open();
using (SqlCommand cmd = new SqlCommand("UPDATE Images SET ImageData = @p1 WHERE ID = @p2", conn))
{
cmd.Parameters.AddWithValue("@p1", imgdata);
cmd.Parameters.AddWithValue("@p2", id);
cmd.ExecuteNonQuery();
}
}
}