Question

怎么ajax实现jsp的验证码部分刷新

Answer 1

<script language="javascript">
function loadimage(){
document.getElementById("randImage").src = "image.jsp?"+Math.random();
}
</script>
<img alt="code..." name="randImage" id="randImage" src="image.jsp" border="1" >
image.jsp
<%@ page contentType="image/jpeg;charset=GBK" import="java.awt.*, java.awt.image.*,java.util.*,javax.imageio.*" %>
<%@ page import="java.io.OutputStream" %>
<%!
Color getRandColor(int fc,int bc)
{
Random random = new Random();
if(fc>255) fc=255;
if(bc>255) bc=255;
int r=fc+random.nextInt(bc-fc);
int g=fc+random.nextInt(bc-fc);
int b=fc+random.nextInt(bc-fc);
return new Color(r,g,b);
}
%>
<%
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
int width=80, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

Graphics g = image.getGraphics();
Random random = new Random();
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}
String sRand="";
for (int i=0;i<6;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
g.drawString(rand,13*i+6,16);
}
// 将认证码存入SESSION
session.setAttribute("rand",sRand);
g.dispose();
OutputStream os=response.getOutputStream();

ImageIO.write(image, "JPEG", os);

os.flush();
os.close();
os=null;
response.flushBuffer();
out.clear();
out = pageContext.pushBody();
%>