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[英]Wicket WebApplication/WebPage circular dependency using spring
[英]Using EJB in Wicket WebPage
當我使用@EJB批注通過普通HttpServlet中的遠程接口訪問無狀態EJB時,它可以正常工作:
public class ListMsgs extends HttpServlet
{
@EJB
private Msgs msgsRI;
...
protected void processRequest(...) ...
{
List msgs = msgsRI.getAll();
...
}
...
}
但是,當我在Wicket WebPage中嘗試相同的操作時,得到的空值是bean的回報:
public class ListM extends WebPage
{
@EJB
private Msgs msgsRI;
...
public ListM()
{
List msgs = msgsRI.getAll(); // NullPointerException
...
}
...
}
此“意外的RuntimeException”的幾行是:
WicketMessage: Can't instantiate page using constructor public testapp.web.ListM()
Root cause:
java.lang.NullPointerException
at testapp.web.ListM.<init>(ListM.java:22)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at org.apache.wicket.session.DefaultPageFactory.createPage(DefaultPageFactory.java:192)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:57)
at org.apache.wicket.request.target.component.BookmarkablePageRequestTarget.newPage(BookmarkablePageRequestTarget.java:298)
at org.apache.wicket.request.target.component.BookmarkablePageRequestTarget.getPage(BookmarkablePageRequestTarget.java:320)
at org.apache.wicket.request.target.component.BookmarkablePageRequestTarget.processEvents(BookmarkablePageRequestTarget.java:234)
at org.apache.wicket.request.AbstractRequestCycleProcessor.processEvents(AbstractRequestCycleProcessor.java:92)
at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1250)
at org.apache.wicket.RequestCycle.step(RequestCycle.java:1329)
at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1428)
at org.apache.wicket.RequestCycle.request(RequestCycle.java:545)
at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:479)
at org.apache.wicket.protocol.http.WicketServlet.doGet(WicketServlet.java:138)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
....
有部署到GlassFish v2.1.1服務器的帶Bean的ejb模塊和帶servlet的wick和Web頁的Web模塊(如果有任何意義)。
如何通過檢票頁面中的遠程接口使用我的企業bean?
您可以在以下位置找到Java EE集成項目: http : //wicketstuff.org/confluence/display/STUFFWIKI/wicket-contrib-javaee
由於Wicket組件實例化不受DI容器的管理,因此它必須提供代理注入機制。 有一個標准的實現方法,基於org.apache.wicket.injection.Injector類。
進一步回答先前的答案:由於ejb3樣式,在第一步使用@Stateless注釋聲明name元素是一種更好的方法,而不是在如何使用ejb注釋的整個第三步中聲明。
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