在 servlet 中覆盖 doGet

我正在尝试制作一个servlet，并试图覆盖我的doGet方法。@Override doGet中存在错误

protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

它正在处理中请求错误来了。具体的错误消息是：

The method processRequest(HttpServletRequest, HttpServletResponse) is undefined for the type 
CookieUsageServlet

有人知道为什么我会收到此错误吗？

   package ExamplePackage;
import java.io.IOException;
import java.util.Date;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/CookieUsageServlet")
public class CookieUsageServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie cookie = getCookie(request, response);
        printResponse(response, cookie);
    }

    private Cookie getCookie(HttpServletRequest request, HttpServletResponse response) {
        Cookie cookie = null;
        Cookie[] cookiesArray = request.getCookies();
        if(cookiesArray != null) {
            for(int x = 0; x < cookiesArray.length; x++) {
                if(cookiesArray[x].getName().equals("test_cookie")) cookie = cookiesArray[x];
            }
        }
        if(cookie != null) {
            System.out.println("cookie retrieved");
        } else {
            int timeToExpireCookie = new Integer(getServletContext().getInitParameter("time-to-expire-cookie")).intValue();
            cookie = new Cookie("test_cookie", Long.toString(new Date().getTime()));
            cookie.setMaxAge(timeToExpireCookie);
            cookie.setPath(request.getContextPath()); // Sti til login
            System.out.println("Cookie created...");
            response.addCookie(cookie);
        }
        return cookie;
    }
    private void printResponse(HttpServletResponse response, Cookie cookie) throws IOException {
        PrintWriter printWriter = response.getWriter();
        response.setContentType("text/html");
        printWriter.println("<html>");
        printWriter.println("<head><title>Cookie In JAVA servlet</title></head>");
        printWriter.println("<body>");
        printWriter.println("<cookie name: " + cookie.getName() + "<br>");
        printWriter.println("<cookie value: " + cookie.getValue() + "<br>");
        printWriter.println("<time to expire cookie in seconds: " + cookie.getMaxAge() + "<br>");
        printWriter.println("</body>");
        printWriter.println("</html>");

    }
}

根据异常getServletContext().getInitParameter("time-to-expire-cookie")值为 null 。

正确的代码是：

package ExamplePackage;
import java.io.IOException;
import java.util.Date;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/CookieUsageServlet")
public class CookieUsageServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie cookie = getCookie(request, response);
        printResponse(response, cookie);
    }

    private Cookie getCookie(HttpServletRequest request, HttpServletResponse response) {
        Cookie cookie = null;
        Cookie[] cookiesArray = request.getCookies();
        if(cookiesArray != null) {
            for(int x = 0; x < cookiesArray.length; x++) {
                if(cookiesArray[x].getName().equals("test_cookie")) cookie = cookiesArray[x];
            }
        }
        if(cookie != null) {
            System.out.println("cookie retrieved");
        } else {
            int timeToExpireCookie = new Integer(getServletContext().getInitParameter("time-to-expire-cookie")).intValue();
            cookie = new Cookie("test_cookie", Long.toString(new Date().getTime()));
            cookie.setMaxAge(timeToExpireCookie);
            cookie.setPath(request.getContextPath()); // Sti til login
            System.out.println("Cookie created...");
            response.addCookie(cookie);
        }
        return cookie;
    }
    private void printResponse(HttpServletResponse response, Cookie cookie) throws IOException {
        PrintWriter printWriter = response.getWriter();
        response.setContentType("text/html");
        printWriter.println("<html>");
        printWriter.println("<head><title>Cookie In JAVA servlet</title></head>");
        printWriter.println("<body>");
        printWriter.println("<cookie name: " + cookie.getName() + "<br>");
        printWriter.println("<cookie value: " + cookie.getValue() + "<br>");
        printWriter.println("<time to expire cookie in seconds: " + cookie.getMaxAge() + "<br>");
        printWriter.println("</body>");
        printWriter.println("</html>");

    }
}

网站.xml：

<context-param>
        <param-name>time-to-expire-cookie</param-name>
        <param-value>20</param-value>
  </context-param>

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