java_利用session校验图片认证码
RegisterServlet：检验server，client验证码是否一致
ImageServlet: 产生验证码
<!DOCTYPE html>
<html>
<head>
<title>Register.html</title>
<script type="text/javascript">
function ChangeImage(img){
img.src=img.src+"?"+new Date().getTime();
}
</script>
</head>
<body>
<form action="/NANA/servlet/RegisterServlet">
用户名:<input type="text" ><br />
密码:<input type="text"><br />
认证码：<input type="text" name="checkcode"><img alt="" src="/NANA/servlet/ImageServlet" onclick="ChangeImage(this)" alt="change" style="cursor:pointer"><br/>
<input type="submit" value="submit">
</form>
</body>
</html>
RegisterServlet：
public class RegisterServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String c_checkcode = request.getParameter("checkcode");
String s_checkcode = (String) request.getSession().getAttribute("checkcode");
if(c_checkcode!=null&&s_checkcode!=null&&c_checkcode.equals(s_checkcode)){
System.out.println("处理请求");
}else{
System.out.println("认证码错误");
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
ImageServlet
public class ImageServlet extends HttpServlet {
private static final int WIDTH = 120;
private static final int HEIGHT = 25;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
setBackGround(g);
setBorder(g);
drawRandomLine(g);
String random = drawRandmNumber((Graphics2D) g);
// add into server checkcode
request.getSession().setAttribute("checkcode", random);
response.setContentType("image/jpeg");
response.setDateHeader("expries", -1);
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
ImageIO.write(image, "jpg", response.getOutputStream());
}
private String drawRandmNumber(Graphics2D g) {
// TODO Auto-generated method stub
g.setColor(Color.RED);
g.setFont(new Font("宋体", Font.BOLD, 20));
StringBuffer sb = new StringBuffer();
int x = 5;
for (int i = 0; i < 4; i++) {
int degree = new Random().nextInt() % 30;
String num = (new Random().nextInt(10)) + "";
sb.append(num);
g.rotate(degree * Math.PI / 180, x, 20);
g.drawString(num, x, 20);
g.rotate(-degree * Math.PI / 180, x, 20);
x += 30;
}
return sb.toString();
}
private void drawRandomLine(Graphics g) {
// TODO Auto-generated method stub
g.setColor(Color.GREEN);
for (int i = 0; i < 5; i++) {
int x1 = new Random().nextInt(WIDTH);
int y1 = new Random().nextInt(HEIGHT);
int x2 = new Random().nextInt(WIDTH);
int y2 = new Random().nextInt(HEIGHT);
g.drawLine(x1, y1, x2, y2);
}
}
private void setBackGround(Graphics g) {
// TODO Auto-generated method stub
g.setColor(Color.WHITE);
g.fillRect(0, 0, WIDTH, HEIGHT);
}
private void setBorder(Graphics g) {
// TODO Auto-generated method stub
g.setColor(Color.BLUE);
g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
