struts1 登陆验证码实现

response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
OutputStream os=response.getOutputStream();
Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
g.setColor(new Color(255, 255, 255));
for (int i=0;i<155;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(40);
int yl = random.nextInt(40);
g.drawLine(x,y,x+xl,y+yl);
}
String sRand="";
for (int i=0;i<4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
g.setColor(new Color(0, 0, 0));
g.drawString(rand,14 * i,18);
}
//赋值验证码
CHECK_IMAGE = sRand;
g.dispose();
ImageIO.write(image, "jpeg",os);
request.setAttribute("image", image);
response.flushBuffer();
os.flush();
os.close();
os=null;
return null;
}catch(IllegalStateException e){
System.out.println(e.getMessage());
e.printStackTrace();
}

<img src="index.do?command=toLoginpicture" id="Verify"  name="Verify" style="cursor:hand;" alt="看不清，换一张" onclick="changePic()"/><span style="color:red">${checkimage}</span>