SessionUtil

import cn.edu.zzuli.bean.Shop;
import cn.edu.zzuli.bean.User;
import org.apache.catalina.servlet4preview.http.HttpServletRequest;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpSession;

/**
* @ClassName SessionUtil
* @Description 对于Session中的操作，封装起来，因为键值对中的键是String类型，不便于控制，在这里可以隐藏细节。
* @Author 过道
* @Date 2018/12/24 21:00
* @Version 1.0
*/
public class SessionUtil {
// 获取一个session对象
private static HttpSession session = getSession();

/**
* user在session中的名字，也就是键值对的键。
*/
private static final String USER_NAME_IN_SESSION = "user";
/**
* shop在session中的名字，也就是键值对的键。
*/
private static final String SHOP_NAME_IN_SESSION = "shop";

/**
* 获取session 的方法
*
* @return HttpSession
*/
public static HttpSession getSession() {
HttpSession session = null;
try {
session = getRequest().getSession();
} catch (Exception e) {
}
return session;
}

/**
* 获取一个request对象的方法
*
* @return HttpServletRequest
*/
public static HttpServletRequest getRequest() {
ServletRequestAttributes attrs = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
return (HttpServletRequest) attrs.getRequest();
}

/**
* 从session中获取到当前用户
*
* @return
*/
public static User getUserFromSession() {
return (User) session.getAttribute(USER_NAME_IN_SESSION);
}

/**
* 更新Session中的user
*
* @return
*/
public static User updateUserInSession(User user) {
// 直接放入user，顶替掉原来session中的user
return putUserIntoSession(user);
}

/**
* 将user放入Session对象中
*
* @param user 用户
* @return
*/
public static User putUserIntoSession(User user) {
session.setAttribute(USER_NAME_IN_SESSION, user);
return getUserFromSession();
}


/**
* 从session中移除User对象
*
* @return
*/
public static User removeUserFromSession() {
User user = getUserFromSession();
session.removeAttribute(USER_NAME_IN_SESSION);
// 移出商店,如果有的话
if (getShopFromSession() != null) {
removeShopFromSession();
}
return user;
}

/**
* 将shop放入Session对象
*
* @param shop 商店
*/
public static void putShopIntoSession(Shop shop) {
session.setAttribute(SHOP_NAME_IN_SESSION, shop);
}

/**
* 从session中移除User对象
*
* @return
*/
public static Shop removeShopFromSession() {
Shop shop = getShopFromSession();
session.removeAttribute(SHOP_NAME_IN_SESSION);
return shop;
}

/**
* 从Session中获取到Shop
*
* @return 将Session中的Shop返回
*/
private static Shop getShopFromSession() {
return (Shop) session.getAttribute(SHOP_NAME_IN_SESSION);
}

}