第一步：创建一个Servlet文件
//数字随机码
public class generateCode extends HttpServlet {
private static final long serialVersionUID = 5039673797977591965L;
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
processRequest(req, resp);
}
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
processRequest(req, resp);
}
public void processRequest(HttpServletRequest request,
HttpServletResponse response) throws IOException {
response.setContentType("11.gif"); //要设定好一个图片
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
HttpSession session = request.getSession();
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);
}
session.setAttribute("rand", sRand);
g.dispose();
ServletOutputStream responseOutputStream = response.getOutputStream();
ImageIO.write(image, "JPEG", responseOutputStream);
responseOutputStream.flush();
responseOutputStream.close();
}
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);
}
}
第二步 设置web.xml
<servlet>
<servlet-name>showImgCode</servlet-name>
<servlet-class>generateCode </servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>showImgCode</servlet-name>
<url-pattern>/11.GIF</url-pattern>
</servlet-mapping>
第三步 创建相应的JSP
index.jsp
<%@ page contentType="text/html;charset=gb2312"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>认证码输入页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
<script language="JavaScript">
function myrefresh()
{
window.location.reload();
}
</script>
</head>
<body>
<form method=post action="check.jsp">
<table>
<tr>
<td align=left>
系统产生的认证码：
</td>
<td>
<img border=0 src="11.GIF">
<input type="button" value="看不清，在换一张" onclick="myrefresh()">
</td>
</tr>
<tr>
<td align=left>
输入上面的认证码：
</td>
<td>
<input type=text name=rand maxlength=6 value="">
</td>
</tr>
<tr>
<td colspan=2 align=center>
<input type=submit value="提交检测">
</td>
</tr>
</table>
</form>
</body>
</html>
Check.jsp
<%@ page contentType="text/html; charset=gb2312" language="java"
errorPage=""%>
<html>
<head>
<title>认证码验证页面</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="Cache-Control" CONTENT="no-cache">
<META HTTP-EQUIV="Expires" CONTENT="0">
</head>
<body>
<%
String rand = (String) session.getAttribute("rand");
String input = request.getParameter("rand");
%>
系统产生的认证码为：
<%=rand%><br>
您输入的认证码为：
<%=input%><br>
<br>
<%
if (rand.equals(input)) {
%>
<font color=green>输入相同，认证成功！</font>
<%
} else {
%>
<font color=red>输入不同，认证失败！</font>
<%
}
%>
</body>
</html>
==================
长生字符和数据的验证码
public class CharactorCode extends HttpServlet {
private static final long serialVersionUID = 4347521091342882490L;
private Font mFont = new Font("Arial Black", Font.PLAIN, 16);
public void init() throws ServletException {
super.init();
}
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);
}
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("11.gif");
int width = 100, height = 18;
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(1, 1, width - 1, height - 1);
g.setColor(new Color(102, 102, 102));
g.drawRect(0, 0, width - 1, height - 1);
g.setFont(mFont);
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(width - 1);
int y = random.nextInt(height - 1);
int xl = random.nextInt(6) + 1;
int yl = random.nextInt(12) + 1;
g.drawLine(x, y, x + xl, y + yl);
}
for (int i = 0; i < 70; i++) {
int x = random.nextInt(width - 1);
int y = random.nextInt(height - 1);
int xl = random.nextInt(12) + 1;
int yl = random.nextInt(6) + 1;
g.drawLine(x, y, x - xl, y - yl);
}
String sRand = "";
for (int i = 0; i < 6; i++) {
String tmp = getRandomChar();
sRand += tmp;
g.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
g.drawString(tmp, 15 * i + 10, 15);
}
HttpSession session = request.getSession(true);
session.setAttribute("rand", sRand);
g.dispose();
ImageIO.write(image, "JPEG", response.getOutputStream());
}
private String getRandomChar() {
int rand = (int) Math.round(Math.random() * 2);
long itmp = 0;
char ctmp = '\u0000';
switch (rand) {
case 1:
itmp = Math.round(Math.random() * 25 + 65);
ctmp = (char) itmp;
return String.valueOf(ctmp);
case 2:
itmp = Math.round(Math.random() * 25 + 97);
ctmp = (char) itmp;
return String.valueOf(ctmp);
default:
itmp = Math.round(Math.random() * 9);
return String.valueOf(itmp);
}
}
}
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