c#在sql中存取图片image示例

（1）控制台应用程序下演示插入图片

public void insertimg()
{
//将需要存储的图片读取为数据流
filestream fs = new filestream(@"e:\c.jpg", filemode.open,fileaccess.read);
byte[] btye2 = new byte[fs.length];
fs.read(btye2 , 0, convert.toint32(fs.length));
fs.close();

using (sqlconnection conn = new sqlconnection(sqlconnstr))
{
conn.open();
sqlcommand cmd = new sqlcommand();
cmd.connection = conn;
cmd.commandtext = "insert into t_img(imgfile) values(@imgfile)";
sqlparameter par = new sqlparameter("@imgfile", sqldbtype.image);
par.value = bt;
cmd.parameters.add(par);

int t=(int)(cmd.executenonquery());
if (t > 0)
{
console.writeline("插入成功");
}
conn.close();
}
}

（2）控制台应用程序下读出并生成图片到物理位置

public void read()
{
byte[] mydata = new byte[0];
using (sqlconnection conn = new sqlconnection(sqlconnstr))
{
conn.open();
sqlcommand cmd = new sqlcommand();
cmd.connection = conn;
cmd.commandtext = "select * from t_img";
sqldatareader sdr = cmd.executereader();
sdr.read();
mydata = (byte[])sdr["imgfile"];//读取第一个图片的位流
int arraysize= mydata.getupperbound(0);//获得数据库中存储的位流数组的维度上限，用作读取流的上限

filestream fs = new filestream(@"c:\00.jpg", filemode.openorcreate, fileaccess.write);
fs.write(mydata, 0, arraysize);
fs.close();   //-- 写入到c:\00.jpg。
conn.close();
console.writeline("读取成功");//查看硬盘上的文件
}
}

（3）web下picshow.aspx页将图片读取出来并写入到浏览器上呈现

public void read()
{
byte[] mydata = new byte[0];
using (sqlconnection conn = new sqlconnection(sqlconnstr))
{
conn.open();
sqlcommand cmd = new sqlcommand();
cmd.connection = conn;
cmd.commandtext = "select * from t_img";
sqldatareader sdr = cmd.executereader();
sdr.read();
mydata = (byte[])sdr["imgfile"];
response.contenttype = "image/gif";
response.binarywrite(mydata);
conn.close();
response.write("读取成功");
}

（4）在web中可以如上picshow.aspx页面读取并显示图片，而真正引用该图片时如下示例

<img src="picshow.aspx" width="500" height="300" />

 （5）winform下将图片写入到sql数据库image类型字段中的方法和以上方法基本一致，仅区别于可以利用多个对话框来帮助选取存储图片等，各个属性可以方便的利用上

（6）winform下读取图片在picturebox控件中显示出来

方法一：利用memorystream 和system.drawing.image

public void read()
{
byte[] mydata = new byte[0];
using (sqlconnection conn = new sqlconnection(sqlconnstr))
{
conn.open();
sqlcommand cmd = new sqlcommand();
cmd.connection = conn;
cmd.commandtext = "select * from t_img";
sqldatareader sdr = cmd.executereader();
sdr.read();
mydata = (byte[])sdr["imgfile"];

memorystream mystream = new memorystream(mydata);
//用指定的数据流来创建一个image图片
system.drawing.image img = system.drawing.image.fromstream(mystream, true);

system.windows.forms.picturebox picbox = new picturebox();
picbox.image = img;
picbox.left = 30;
picbox.top = 80;
picbox.width = 800;
picbox.height = 500;
this.controls.add(picbox);

mystream.close();
conn.close();
}
}

方法二：将流直接读取成图片并写入到物理位置，然后再行利用该图片呈现

void read()
{
using (sqlconnection conn = new sqlconnection(sqlconnstr))
{
conn.open();
sqlcommand cmd = new sqlcommand();
cmd.connection = conn;
cmd.commandtext = "select * from t_img";
sqldatareader sdr = cmd.executereader();
sdr.read();

byte[] image_img = (byte[])sdr["imgfile"];
if (image_img.length == 0)
{
return;
}
int filelength = image_img.length;
string imagename = "1.jpg";
string myurl = environment.currentdirectory + "\\" + imagename;
filestream fs = new filestream(myurl, filemode.openorcreate,fileaccess.write);
binarywriter bw = new binarywriter(fs);
bw.basestream.write(image_img, 0, filelength);
bw.flush();
bw.close();
system.windows.forms.picturebox picbox = new picturebox();

//为picbox添加图片方法一
//picbox.imagelocation = myurl;
//picbox.width = 800;
//picbox.height = 300;

 

//为picbox添加图片方法二
bitmap bitmap = new bitmap(myurl);
picbox.width = 100;//bitmap.width;
picbox.height = 80;//bitmap.height;
picbox.image = (image)bitmap;
picbox.sizemode = system.windows.forms.pictureboxsizemode.stretchimage;
picbox.left = 20;
picbox.top = 30;

this.controls.add(picbox);
conn.close();

}
}