cookie的简单使用

1. 创建cookie对象并保存到客户端

/**
 * 本类用来演示: 服务器端创建cookie
 *
 * @author: success
 * @date: 2021/3/30 1:41 下午
 */
@WebServlet(urlPatterns = "/cookie/create")
public class CookieCreateAction extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1. 创建cookie对象
        String username = "驰星";
        //需要对中文进行二级编码
        username = URLEncoder.encode(username,"utf-8");
        username = URLEncoder.encode(username,"utf-8");

        Cookie c = new Cookie("loginInfo",username+":123");
        //2. 设置path
        c.setPath("/");

        //4. 设置有效期
        c.setMaxAge(60);//单位是s

        //3. 通过响应头信息将cookie发送到浏览器端
        resp.addCookie(c);

    }
}

2. 从客户端获取cookie

/**
 * 本类用来演示: 获取cookie
 *
 * 客户端每次发送请求的时候会在请求头信息中将cookie发送到server
 *
 * @author: success
 * @date: 2021/3/30 1:54 下午
 */
@WebServlet(urlPatterns = "/cookie/get")
public class CookieGetAction extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1. 获取客户端发送过来的所有的cookie
        Cookie[] cookies = req.getCookies();
        //2. 为了防止抛出java.lang.NullPointerException空指针异常
        //非空判断
        if(null!=cookies && cookies.length>0){
            //3. 遍历这个cookie
            for (Cookie cookie : cookies) {
                if("loginInfo".equals(cookie.getName())){
                    //4. 获取该cookie中的value
                    String value = cookie.getValue();
                    //5. java.lang.String的切割方法
                    String[] arr = value.split(":");
                    //6. 注意username如果是中文,当初进行二级编码操作
                    String uname = URLDecoder.decode(URLDecoder.decode(arr[0],"utf-8"),"utf-8");
                    String pwd = arr[1];
                    System.out.println(uname);
                    System.out.println(pwd);
                }
            }
        }
    }
}