sessionutil.java

该代码是Java数据库高级编程宝典中的重要的代码

package jdbcbook.shopping.util;

import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServletRequest;

import jdbcbook.shopping.form.Userinfo;
import jdbcbook.shopping.bean.Cart;

public class SessionUtil
{
	public static final String SESSION_USERINFO = "global__session_userinfo";
	public static final String SESSION_CART = "global__session_cart";

	// 保存用户信息到Session中
	public static void logon( HttpServletRequest request, Userinfo userinfo )
	{
		HttpSession session = request.getSession();
		session.setAttribute( SESSION_USERINFO, userinfo );
	}

	// 从Session中得到用户的信息
	public static Userinfo getUserinfo( HttpServletRequest request )
	{
		return (Userinfo)getObject( request, SESSION_USERINFO );
	}

	// 清除Session中的用户信息
	public static void logout( HttpServletRequest request )
	{
		removeAttribute( request, SESSION_USERINFO );
	}

	// 保存购物车到Session中
	public static void addCart( HttpServletRequest request, Cart cart )
	{
		HttpSession session = request.getSession();
		session.setAttribute( SESSION_CART, cart );
	}

	// 得到购物车信息
	public static Cart getCart( HttpServletRequest request )
	{
		return (Cart)getObject( request, SESSION_CART );
	}

	// 清空购物车
	public static void cleanCart( HttpServletRequest request )
	{
		removeAttribute( request, SESSION_CART );
	}

	// 根据属性的名字得到Session中对象的名称
	public static Object getObject( HttpServletRequest request, String attribute )
	{
		HttpSession session = request.getSession();
		return session.getAttribute( attribute );
	}

	// 清除Session中的某个属性
	public static void removeAttribute( HttpServletRequest request, String attribute )
	{
		HttpSession session = request.getSession();
		session.removeAttribute( attribute );
	}
}