asp.net实现验证码

#region 实现一个验证码的类

public class validatecode
{
private bitmap validateimage;
private graphics g;
public validatecode()
{
validateimage = new bitmap(120, 30, pixelformat.format24bpprgb);
g = graphics.fromimage(validateimage);
}

public void drawvalidatecode(page e, string i)
{
g.drawstring(i, new font("黑体",16,fontstyle.bold),new solidbrush(color.white),new pointf(2,4));
g.fillrectangle(new lineargradientbrush(new point(0,0), new point(120,30), color.fromargb(0,0,0,0),color.fromargb(255,255,255,255)),0,0,120,30);
//validateimage.save(e.outputstream, imageformat.jpeg);
g.save();
memorystream ms=new memorystream();
validateimage.save(ms,system.drawing.imaging.imageformat.gif);
e.response.clearcontent();
e.response.contenttype="image/gif";
e.response.binarywrite(ms.toarray());
e.response.end();
//validateimage.save(e.mappath("numimage/validateimage.gif"), imageformat.gif);
//e.end();
}
}

#endregion

也综合了别人的一部分代码。：）