假设我们希望在客户端浏览器端使用XHR调用完全实现基于休息的购物车，并在服务器端使用java-ee实现休息服务。我们使用JAAS来保证安全。
客户端将登录，购物，关闭浏览器，稍后返回继续购物，记住他的状态，而无需再次登录。
他的状态究竟是如何保留的？
下面是购物车的名义有状态bean，必须将其注入REST资源，该资源将成为客户端和业务逻辑之间的接口：
@Stateful
public class ClientCart{
@Resource private SessionContext ctx;
private List<String> items; //contains a list of products
@PostConstruct
private void createCart(){
/*
init stuff like db connection...
get name of user with ctx.getCallerPrincipa()
check if user had items in cart in the db
if there were items, create a list: items = new LinkedList()<>;
else: populate items with whatever was in db
*/
}
public List getItems(){ /* return the cart... */ }
public void addItem(String item){ /*do a items.add(item); */}
@PrePassivate
private void maintenanceOnSleep(){
/*
Called when the server decided to suspend this instance due to long time of inactivity - when user close browser, etc...
Does clean up tasks like closing a db connection
*/
}
@PostActivate
private void maintenanceOnActivate(){
/*
Opposite of @PrePassivete - open the db connection...
*/
}
@Remove
public void logout(){ /* nothing in here... */ }
@PreDestroy
public void cleanUP(){
/* called when error happens or logout() is explicitly called, will send purge instance vars like items to db and close connections.
}
}
现在我如何制作其余资源？由于rest是请求范围的，我不能注入有状态的bean ...
@Path("/shop")
public class ShoppingCart{
@GET
@Path("/login/{user}/{pass}
public void (@Context HttpServletRequest rq, @PathParam("user") String u, @PathParam("pass") String p {
/*
we do programmatic logins with rq.login(u, p); ... and then what happens? :)
*/
}
}