javaweb中cookic-优快云博客

本文链接：https://blog.youkuaiyun.com/m0_55680183/article/details/121371495

本文介绍了JavaWeb中Cookie对象的原理和使用，通过创建Servlet示例展示了如何创建Cookie并将其发送给客户端，从而实现数据的会话持久化。

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1.Cookie对象：
cookie是一种会话技术,它用于将会话过程中的数据保存到用户的浏览器中,从而使浏览器和服务器可以更好的地进行数据交互;
创建Serlet:
创建一个chapter05项目,创建一个自己喜欢的包,在该包中编写一个为LastAccessSerclet的Servlet类,实现获取Cookiie信息并将当前时间Cookie值发送给客户端;
代码如下:

package chapter05.access;
import java.io.IOException;
import java.util.Date;
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 jdk.javadoc.doclet.Reporter;
/**
 * Servlet implementation class LastAccessServlet
 */
@WebServlet("/LastAccessServlet")
public class LastAccessServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
    /**
     * @see HttpServlet#HttpServlet()
     */
    public LastAccessServlet() {
        // TODO Auto-generated constructor stub
    }
	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setContentType("text/html;charset=utf-8");
		Cookie[ ] cookies=request.getCookies();
		String lastTime=null;
		for (int i = 0; cookies != null&&i<cookies.length; i++) {
			String name = cookies[i].getName();
			if ("lastaccess".equals(name)) {
				lastTime=cookies[i].getValue();
			}
		}
		if (lastTime==null) {
			response.getWriter().print("您是第一次访问本网站!");
		}else {
			response.getWriter().print("您上次访问的时间是:"+lastTime);
		}
		String time = String.format("%tF%<tT", new Date());
		Cookie cookie=new Cookie("lastaccess", time);
		Cookie cookie1 =new Cookie("dashuju","2004");
		response.addCookie(cookie);
		response.addCookie(cookie1);
	}
	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
}
}