Servlet中Cookie實用示例（含刪除）

使用Cookie 顯示/清除 上次訪問時間

效果圖

用於設置並顯示cookie的servlet代碼，注意：第一次訪問時由於沒有歷史cookie所以不會顯示時間，只會新建cookie，此時刷新可以看到上次登錄時間

package ser.david;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

public class CookieDemo extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        PrintWriter out = response.getWriter();
        out.print("<a href='/delcookie'>清除上次訪問時間</a><br/>");//輸出跳轉到刪除cookie的servlet按鈕
        out.print("您上次訪問的時間是：");

        //獲取cookie
        Cookie cookies[] = request.getCookies();
        for (int i = 0; cookies != null && i < cookies.length; i++) {
            if (cookies[i].getName().equals("lastAccessDate")) {
                long longtime = Long.parseLong(cookies[i].getValue());
                Date date = new Date(longtime);
                out.print(date.toLocaleString());

            }
        }
        //設置最新的時間cookie
        Cookie cookie = new Cookie("lastAccessDate", System.currentTimeMillis() + "");
        cookie.setMaxAge(30 * 24 * 3600);//過期時間
        cookie.setPath("/cookie");//作用於當前頁面
        response.addCookie(cookie);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

用於刪除cookie的servlet代碼

package ser.david;
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;
import java.io.IOException;

@WebServlet(name = "DeleteCookie")
public class DeleteCookie extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie cookie=new Cookie("lastAccessDate",System.currentTimeMillis()+"");
        cookie.setMaxAge(0);//刪除
        cookie.setPath("/cookie");
        response.addCookie(cookie);
        response.sendRedirect("/cookie");//**重定向回到顯示cookie的頁面，可以看到頁面上已經不顯示上次訪問的時間，但是！！！由於我們又訪問了一次cookie頁面，給服務器重新發送了一個請求，所以實際上又生成了新的cookie（加載頁面後），刷新可看到**
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    }

}

相關配置文件代碼

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

    <servlet>
        <servlet-name>cookie</servlet-name>
        <servlet-class>ser.david.CookieDemo</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>cookie</servlet-name>
        <url-pattern>/cookie</url-pattern>
    </servlet-mapping>
    <servlet>
        <servlet-name>delCookie</servlet-name>
        <servlet-class>ser.david.DeleteCookie</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>delCookie</servlet-name>
        <url-pattern>/delcookie</url-pattern>
    </servlet-mapping>
</web-app>