Cookie是一种存储在客户端信息的技术。在上一页中,我们已经了解了很多有关Cookie的技术,例如:如何创建cookie,如何删除cookie,如何获取cookie等。
在这个示例中,我们将使用servlet cookie创建一个登录和注销应用的示例。在此示例中将创建3个链接:登录,注销和配置文件。 用户必须先登录才能进入个人资料页面。如果用户已注销,则需要再次登录才能访问个人资料页面。

启动Eclipse,创建一个动态Web应用项目:LoginServletApp,完整的目录结构如下:

目录结构

在此应用程序中,需要创建以下几个文件:

  • index.html
  • link.html
  • login.html
  • LoginServlet.java
  • LogoutServlet.java
  • ProfileServlet.java
  • web.xml

文件:index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Servlet登录示例</title>
</head>
<body>
    <h1>欢迎使用Cookie登录应用</h1>
    <a href="login.html">登录</a>|
    <a href="LogoutServlet">注销</a>|
    <a href="ProfileServlet">个人信息</a>
</body>
</html>

文件:link.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <a href="login.html">登录</a>|
    <a href="LogoutServlet">注销</a>|
    <a href="ProfileServlet">个人信息</a>
<hr>  
</body>
</html>

文件:login.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>登录页面</title>
</head>
<body>
    <form action="LoginServlet" method="post">
        用户名:<input type="text" name="name"><br> 密码:<input
            type="password" name="password"><br> <input
            type="submit" value="登录">
    </form>
</body>
</html>

文件:LoginServlet.java

package com.xntutor.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request HttpServletResponse response)
            throws ServletException IOException {
        response.setContentType("text/html;charset=utf-8");
        response.setCharacterEncoding("utf-8");
        PrintWriter out = response.getWriter();

        request.getRequestDispatcher("link.html").include(request response);

        String name = request.getParameter("name");
        String password = request.getParameter("password");

        if (password.equals("admin123")) {
            out.print("登录系统成功!");
            out.print("<br>您好 " + name);

            Cookie ck = new Cookie("name" name);
            response.addCookie(ck);
        } else {
            out.print("抱歉,用户名或密码错误!");
            request.getRequestDispatcher("login.html").include(request response);
        }

        out.close();
    }

}

文件:LogoutServlet.java

package com.xntutor.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LogoutServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request HttpServletResponse response)
            throws ServletException IOException {
        response.setContentType("text/html;charset=utf-8");
        response.setCharacterEncoding("utf-8");
        PrintWriter out = response.getWriter();

        request.getRequestDispatcher("link.html").include(request response);

        Cookie ck = new Cookie("name" "");
        ck.setMaxAge(0);
        response.addCookie(ck);

        out.print("你已经成功注销!");
    }
}

文件:ProfileServlet.java

package com.xntutor.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ProfileServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request HttpServletResponse response)
            throws ServletException IOException {
        response.setContentType("text/html;charset=utf-8");
        response.setCharacterEncoding("utf-8");
        PrintWriter out = response.getWriter();

        request.getRequestDispatcher("link.html").include(request response);

        Cookie ck[] = request.getCookies();
        if (ck != null) {
            String name = ck[0].getValue();
            if (!name.equals("") || name != null) {
                out.print("<b>欢迎来到个人资料</b>");
                out.print("<br>你好 " + name);
            }
        } else {
            out.print("请先登录~");
            request.getRequestDispatcher("login.html").include(request response);
        }
        out.close();
    }
}

文件:web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    id="WebApp_ID" version="3.0">
    <display-name>LoginServletApp</display-name>
    <servlet>
        <description></description>
        <display-name>LoginServlet</display-name>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>com.xntutor.servlet.LoginServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/LoginServlet</url-pattern>
    </servlet-mapping>
    <servlet>
        <description></description>
        <display-name>ProfileServlet</display-name>
        <servlet-name>ProfileServlet</servlet-name>
        <servlet-class>com.xntutor.servlet.ProfileServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ProfileServlet</servlet-name>
        <url-pattern>/ProfileServlet</url-pattern>
    </servlet-mapping>
    <servlet>
        <description></description>
        <display-name>LogoutServlet</display-name>
        <servlet-name>LogoutServlet</servlet-name>
        <servlet-class>com.xntutor.servlet.LogoutServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LogoutServlet</servlet-name>
        <url-pattern>/LogoutServlet</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>
</web-app>

启动Tomcat服务器,打开浏览器访问下面URL:

Servlet登录和注销Cookies示例

Servlet登录和注销Cookies示例2

Servlet登录和注销Cookies示例3

Servlet登录和注销Cookies示例4