生成验证码的servlet
public class ImgServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public static final int WIDTH = 120;
public static final int HEIGHT = 25;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
//1、设置背景色
setBackGroud(g);
//2.设置边框
setBorder(g);
//3.画干扰线
drawRandomLine(g);
//4.写随机数
String random = drawRandomNum((Graphics2D)g);
request.getSession().setAttribute("checkcode", random);
//5.图形写给浏览器
response.setContentType("image/jpeg");
//发图控制浏览器不要缓存
response.setDateHeader("expries", -1);
response.setHeader("cache-control", "no-cache");
response.setHeader("Pragma", "no-cache");
ImageIO.write(image, "jpg", response.getOutputStream());
}
private void setBackGroud(Graphics g) {
g.setColor(Color.WHITE);
//填充矩形
g.fillRect(0, 0, WIDTH, HEIGHT);
}
private void setBorder(Graphics g) {
g.setColor(Color.BLUE);
g.drawRect(1, 1, WIDTH-2, HEIGHT-2);
}
private void drawRandomLine(Graphics g) {
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);
}
}
//产生随机数并返回
private String drawRandomNum(Graphics2D g) {
g.setColor(Color.RED);
g.setFont(new Font("宋体",Font.BOLD,20));
//中文字所在区间 [\u4e00-\u9fa5]
String base = "ABCDEFGHIJK";
int x = 10;
StringBuilder sb = new StringBuilder();
for(int i=0; i<4; i++){
//设置旋转角度
int degree = new Random().nextInt()%30;//生成正负30内数
String ch = base.charAt(new Random().nextInt(base.length()))+"";
sb.append(ch);
g.rotate(degree*Math.PI/180, x, 20);
g.drawString(ch, x, 20);
g.rotate(-degree*Math.PI/180, x, 20);//旋转回去
x+=30;
}
return sb.toString();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
}
}
提交表单
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
//实现图片转换的函数
/* function changeImage(img){
img.src = img.src+"?"+new Date().getTime();
} */
</script>
</head>
<body>
<form action="/day07/ImgCheck">
用户名：<input type="text" name="username"><br>
密 码：<input type="password" name="password"><br>
验证码：<input type="text" name="checkcode">
<img src="/day07/ImgServlet" onclick="this.src=this.src+'?'+new Date().getTime()" alt="换一张" style="cursor:pointer"><br>
<input type="submit" value="提交">
</form>
</body>
</html>
验证的servlet
public class ImgCheck extends HttpServlet {
private static final long serialVersionUID = 1L;
protected 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("登陆成功");
}else{
System.out.println("验证失败");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
}
}