创建一个servlet 应用程序,该应用程序的用户通过用户名和密码进行登录。当用户登录时,它应该显示消息“cookie created successfully”,并跟踪用户访问网站的次数。为了实现这一点,servlet应该为第一次访问Web 站点的用户创建一个包含个性化点击计数器的cookie。这些cookies 与响应一起发送给用户。对于来自同一用户的每个后续请求,servlet 将从保存的cookie 中检索计数器并将其递增。当计数器值超过4 时,servlet 将显示一条消息,指出有礼物正在等待用户。
时间: 2023-05-30 11:08:01 浏览: 92
首先,需要在web.xml文件中配置servlet,指定servlet的名称、映射路径和类名:
```
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.example.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
```
接下来,创建LoginServlet类,实现doGet和doPost方法:
```
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final String USERNAME = "admin";
private static final String PASSWORD = "password";
private static final String COOKIE_NAME = "clickCounter";
private static final int MAX_CLICKS = 4;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><body>");
out.println("<form method=\"post\">");
out.println("Username: <input type=\"text\" name=\"username\"><br>");
out.println("Password: <input type=\"password\" name=\"password\"><br>");
out.println("<input type=\"submit\" value=\"Login\">");
out.println("</form>");
out.println("</body></html>");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
if (username.equals(USERNAME) && password.equals(PASSWORD)) {
Cookie[] cookies = request.getCookies();
Cookie clickCounter = null;
if (cookies != null) {
for (Cookie cookie : cookies) {
if (cookie.getName().equals(COOKIE_NAME)) {
clickCounter = cookie;
break;
}
}
}
int clicks = 0;
if (clickCounter != null) {
clicks = Integer.parseInt(clickCounter.getValue());
}
clicks++;
if (clicks <= MAX_CLICKS) {
Cookie newCookie = new Cookie(COOKIE_NAME, String.valueOf(clicks));
response.addCookie(newCookie);
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><body>");
out.println("Cookie created successfully<br>");
out.println("You have visited this site " + clicks + " times<br>");
out.println("</body></html>");
} else {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><body>");
out.println("You have visited this site more than " + MAX_CLICKS + " times.<br>");
out.println("A gift is waiting for you!<br>");
out.println("</body></html>");
}
} else {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><body>");
out.println("Invalid username or password<br>");
out.println("</body></html>");
}
}
}
```
在doPost方法中,首先检查用户名和密码是否正确。如果正确,则从请求中获取所有cookie,并查找名为“clickCounter”的cookie。如果找到了这个cookie,就从它的值中获取当前点击次数。否则,点击次数为0。然后,递增点击次数,并创建一个新的cookie来保存它。最后,在响应中输出相应的消息。
如果点击次数超过了最大值,就输出另一条消息,提示用户有礼物在等待。
当用户访问Web站点时,可以在浏览器的开发者工具中查看cookies,以验证计数器是否按预期递增。