Question

我在youtube上关于创建cookie的教程。我键入了正确的代码，但我在以下行中收到错误：

cookie = new Cookie("test_cookie", Long.toString(new Date().getTime()));

错误说：The constructor Date() is undefined.当有人可以在视频中运行时，有谁知道我是如何得到此错误的： https://www.youtube.com/watch?v=hOColvr3pl0

我猜应该有一个参数，或者？最诚挚的问候Mads

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;

    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>");


    }

}

Answer 1

您正在导入java.sql.Date - 其中没有具有无参数构造函数。你的意思是java.util.Date。

然而，根本不需要创建一个Date对象，以便以毫秒为单位获取当前时间 - 自Unix-epoch以来：

cookie = new Cookie("test_cookie", Long.toString(System.currentTimeMillis());

（或者理想情况下，在代码中注入某种Clock表示，这样您就可以更轻松地进行测试。）

Answer 2

java.sql.Date没有no-arg构造函数。

java.sql.Date将其更改为java.util.Date

cookie = new Cookie("test_cookie", Long.toString(new java.util.Date().getTime()));

Cookie在日期中出错

2 个答案: