正文
java 使用cookie记录用户上一次访问的时间 记住 用户的 登录名
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package cn.itcast.cookie;import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//记住用户最近的一次访问时间：lastAccessTime=23432432432
public class CookieDemo1 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
//取到指定的Cookie lastAccessTime的值，打印到页面上 out.write("您上次访问的时间是："); Cookie cs[] = request.getCookies();
if(cs!=null)
{
for(int i=0;cs!=null&&i<cs.length;i++){
Cookie c = cs[i];
if("lastAccessTime".equals(c.getName())){
String value = c.getValue();
long time = Long.parseLong(value);
out.print(new Date(time).toLocaleString());
}
} }
else
{
out.write("这是你第一次访问！");
}
//把当前访问的时间写回去
Cookie c = new Cookie("lastAccessTime",System.currentTimeMillis()+"");
/* 设置Cookie的最大保存时间，即cookie的有效期，当服务器给浏览器回送一个cookie时，如果在服务器端没有调用setMaxAge方法设置cookie的有效期，
那么cookie的有效期只在一次会话过程中有效，用户开一个浏览器，点击多个超链接，访问服务器多个web资源，然后关闭浏览器，整个过程称之为一次会话，
当用户关闭浏览器，会话就结束了，此时cookie就会失效，如果在服务器端使用setMaxAge方法设置了cookie的有效期，比如设置了30分钟，
那么当服务器把cookie发送给浏览器时，此时cookie就会在客户端的硬盘上存储30分钟，在30分钟内，即使浏览器关了，cookie依然存在，
在30分钟内，打开浏览器访问服务器时，浏览器都会把cookie一起带上，这样就可以在服务器端获取到客户端浏览器传递过来的cookie里面的信息了，
这就是cookie设置maxAge和不设置maxAge的区别，不设置maxAge，那么cookie就只在一次会话中有效，一旦用户关闭了浏览器，那么cookie就没有了，
那么浏览器是怎么做到这一点的呢，我们启动一个浏览器，就相当于启动一个应用程序，而服务器回送的cookie首先是存在浏览器的缓存中的，当浏览器关闭时，
浏览器的缓存自然就没有了，
所以存储在缓存中的cookie自然就被清掉了，而如果设置了cookie的有效期，那么浏览器在关闭时，
就会把缓存中的cookie写到硬盘上存储起来，这样cookie就能够一直存在了。
* */ c.setMaxAge(30*24*60*60);// Integer.MAX_VALUE
c.setPath(request.getContextPath());// c.setPath("/day07");
//将cookie对象添加到response对象中，这样服务器在输出response对象中的内容时就会把cookie也输出到客户端浏览器
response.addCookie(c); //清空
out.write("<a href='/day07/servlet/CookieDemo2'>clear</a>");
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { doGet(request, response);
}}
访问上面的servlet，显示如下。
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" alt="" />
点击 clear ，访问下面的servlet，清除 cookie
package cn.itcast.cookie; import java.io.IOException; import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//清空指定的Cookie
public class CookieDemo2 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Cookie c = new Cookie("lastAccessTime", "");
c.setMaxAge(0);
/*
* setPath()
* 设置cookie的有效路径，比如把cookie的有效路径设置为"/xdp"，那么浏览器访问"xdp"目录下的web资源时，
* 都会带上cookie，再比如把cookie的有效路径设置为"/xdp/gacl"，
* 那么浏览器只有在访问"xdp"目录下的"gacl"这个目录里面的web资源时才会带上cookie一起访问，
* 而当访问"xdp"目录下的web资源时，浏览器是不带cookie的
*
* */
c.setPath(request.getContextPath());
response.addCookie(c);
//设置refresh响应头，让浏览器3秒后跳转到/day07/servlet/CookieDemo1
response.setHeader("Refresh", "3;URL=/day07/servlet/CookieDemo1");
} public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { doGet(request, response);
} }
用户登录的时候，通过勾选，保存用户名，用户在下次进入该网址 登录的时候，不用再输入用户名。
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//读取记住的用户名
String username = "";
String checked = "";//Cookie cs[] = request.getCookies();
for(int i=0;cs!=null&&i<cs.length;i++){//用户第一次登录，cs==null
Cookie c = cs[i];//解析，客户端带过来的cookie ，取出，cookie中保存的用户名。
if("userInfo".equals(c.getName())){
String value = c.getValue();//用户名
username = value;
checked = "checked='checked'";
break;
}
}//提供登录的界面
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.write("<form action='/day07/servlet/LoginServlet' method='post'>");//测试时，用户名先不要使用中文
out.write("用户名:<input type='text' name='username' value='"+username+"'/><br/>");//将cookie 中保存 的用户名，填充到 登录 用户名 框
out.write("密码:<input type='password' name='password' value=''/><br/>");
out.write("<input type='checkbox' name='remember' "+checked+"/>记住用户名<br/>");
out.write("<input type='submit' value='登录'/>");
out.write("</form>");
}
//完成登录
//根据是否需要记住用户名来写Cookie
public class LoginServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
String username = request.getParameter("username");
String password = request.getParameter("password");
String remember = request.getParameter("remember");
//验证用户名和密码
User user = UserDB.findUser(username, password);
if(user==null){
out.write("错误的用户名或密码");
return;
}
//处理cookie： userInfo=gfy
Cookie c = new Cookie("userInfo",username);//将用户名，写入cookie ，保存到浏览器端，用户下次再访问，该路径。会将 保存在浏览器端cookie，一起带过来。
c.setPath(request.getContextPath());
if(remember==null){
//删除cookie
c.setMaxAge(0);
}else{
//记住cookie
c.setMaxAge(Integer.MAX_VALUE);
}
response.addCookie(c);
out.print("恭喜！登录成功");
}
