读写cookie

    Cookie的英文原意是“点心”，它是在客户端访问Web服务器时，服务器在客户端硬盘上存放的信息，好像是服务器送给客户的“点心”。服务器可以根据Cookie来跟踪客户状态。

public class TestCookie extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		Cookie[] cookies = request.getCookies();
		PrintWriter out = response.getWriter();

		if (cookies != null) {
			int len = cookies.length;
			for (int i = 0; i < len; i++) {
				out.println(cookies[i].getName());
				out.println(cookies[i].getMaxAge());
			}
		} else {
			out.println("No cookies");

		}
		response.addCookie(new Cookie("mycookie", "fortest"));

	}

	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {

	}

}

    第一次访问是输出“no cookies”，刷新后就是"mycookie -1"了。