会话跟踪技术 - Cookie 和 Session 快速上手 + 登陆注册案例( 三 )

2023-07-25 生活百科

新建Servlet，创建Cookie对象，存入数据，发送给前端
package priv.dandelion.controller;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("/cookieDemoA")public class AServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 创建Cookie对象 Cookie cookie = new Cookie("name","zhangsan"); // 通过resp将Cookie发送到前端 resp.addCookie(cookie); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doGet(req, resp); }}

2.2.2 获取Cookie

获取客户端携带的所有Cookie数组，使用Request对象
Cookie[] cookies = request.getCookies();
使用Cookie对象的方法获取数据
cookie.getName();cookie.getValue();
案例
需求:在Servlet中获取前一个案例存入在Cookie对象中的数据
1.编写一个新Servlet类，名称为BServlet
2.在BServlet中使用request对象获取Cookie数组，遍历数组，从数据中获取指定名称对应的值
3.启动测试，在控制台打印出获取的值

编写Servlet，使用request对象获取Cookie数组，遍历数组，从数据中获取指定名称对应的值，并在控制台打印
package priv.dandelion.controller;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("/cookieDemoB")public class BServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Cookie[] cookies = request.getCookies(); for (Cookie cookie : cookies) { if ("username".equals(cookie.getName())) { System.out.println(cookie.getName() + "," + cookie.getValue()); break; } } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doGet(req, resp); }}

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