Action类ActionContext.getContext().getSession()报空指针

Question

其他的Action类用ActionContext.getContext().getSession()都没错，为什么在这个Action类里总报空指针？一去掉这句就正常。

严重: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at com.accp.oa.actions.TreeAction$3.nodeSelected(TreeAction.java:94)
at com.jenkov.prizetags.tree.impl.Tree.notifySelectListeners(Tree.java:668)
at com.jenkov.prizetags.tree.impl.Tree.select(Tree.java:340)
at com.jenkov.prizetags.tree.impl.Tree.select(Tree.java:351)
at com.jenkov.prizetags.tree.impl.TreeUpdater.selectUnselectNodes(TreeUpdater.java:280)
at com.jenkov.prizetags.tree.impl.TreeUpdater.update(TreeUpdater.java:122)
at com.jenkov.prizetags.tree.impl.TreeTag.doStartTag(TreeTag.java:242)

这个Action报错：public class TreeAction extends ActionSupport implements java.io.Serializable {}

[img]http://dl.iteye.com/upload/attachment/578092/ea3f3109-f090-341c-931f-d66bb4cbe6fa.png[/img]

Answer 1

[quote]难道ISelectListener类里只能进行控制台输出？可是我需要把监听到的数据到session中，这个怎么办？[/quote]

给tree加一个属性好了 String selectTreeId;
在listener里把selectNode 赋值给tree；
然后在其他地方看看能不能通过tree赋值给session