我正在尝试设置会话属性 [HTTP 或 Portlet 会话]，以便我可以全局访问它（通过门户）。但是，在获取 Session 属性时，它返回的是 null 而不是实际值。

设置会话属性：

@Component(
immediate = true,
property = {
    "com.liferay.portlet.display-category=IPC Sender",
    "com.liferay.portlet.instanceable=true",
    "javax.portlet.display-name=IPC_Sender Portlet",
    "javax.portlet.init-param.template-path=/",
    "javax.portlet.init-param.view-template=/view.jsp",
    "com.liferay.portlet.private-session-attributes=false",
    "javax.portlet.resource-bundle=content.Language",
    "javax.portlet.security-role-ref=power-user,user"
},
service = Portlet.class
)

public class ipcsenderPortlet extends MVCPortlet {

public void hello(ActionRequest actionRequest,
        ActionResponse actionResponse) throws Exception 
{   
//Trying to set HttpSession but its also getting null while retrieving
HttpServletRequest httpreq = PortalUtil.getHttpServletRequest(actionRequest);
HttpSession session = httpreq.getSession(true);
session.setAttribute("transfer", "content");

////Trying to set Portletsession but its also getting null while retrieving
PortletSession portletsession = actionRequest.getPortletSession();
portletsession.setAttribute("sendvalue","abcde", 
PortletSession.APPLICATION_SCOPE);
}
}

获取不同 Portlet 中的会话属性：

@Component(
    immediate = true,
    property = {
        "com.liferay.portlet.display-category=IPC Receiver",
        "com.liferay.portlet.instanceable=true",
        "javax.portlet.display-name=IPC_Receiver Portlet",
        "javax.portlet.init-param.template-path=/",
        "javax.portlet.init-param.view-template=/view.jsp",
        "javax.portlet.resource-bundle=content.Language",
        "com.liferay.portlet.private-session-attributes=false",
        "javax.portlet.security-role-ref=power-user,user"
    },
    service = Portlet.class
)
public class ipcreceiverPortlet extends MVCPortlet 
{
    public void doView(RenderRequest renderRequest, RenderResponse renderResponse) throws IOException, PortletException 
    {
        //HttpSession
         HttpServletRequest httpreq = PortalUtil.getHttpServletRequest(renderRequest);
         HttpSession session = httpreq.getSession();
         String name = (String)session.getAttribute("transfer");
         System.out.println("Session value through HttpSession:"+name);

         //PortletSession
         PortletSession portletsession = renderRequest.getPortletSession();
         String userName = (String) portletsession.getAttribute("sendvalue",PortletSession.APPLICATION_SCOPE);
         System.out.println("\nSession value through PortletSession:"+userName);
    }
}

这不是一个错误！ Liferay 是一个 portlet 容器，在 portlet 规范中，每个 portlet 都是具有不同会话的不同上下文。您试图在一个 portlet 会话中保存数据并在其他 portlet 会话中恢复它，这是不正确的。 Liferay提供了获取门户全局会话的方法：

        PortalSessionThreadLocal.getHttpSession();

该会话可以从门户的每个 portlet 中检索，但重要的是要指定在集群环境中强烈建议不要在全局会话中保存数据，这主要是因为如果您从仅存在于 portlet 中的类保存实例，您可能会从以下位置获得 ClassNotFoundException：其他不知道该类的 portlet。全局会话仅建议用于保存原始数据。