java - WICKET:使用 DatePicker 时无法使用构造函数实例化页面

Question

这次我在将 DatePicker 放在我的 wicket 页面上时遇到问题。

我的代码如下:

public class StateDB extends BasePage {
    private Date date = new Date();
    public StateDB() {
        Form form = new Form("form");
        DateTextField birthDate = new DateTextField("birthDate", new PropertyModel<Date>(
                this, "date"), new StyleDateConverter("S-", true));
        PickDate datePicker = new PickDate();
        datePicker.setShowOnFieldClick(true);
        datePicker.setAutoHide(true);
        birthDate.add(datePicker);
        form.add(birthDate);  
        add(form);
    }
}

当我在服务器上运行它并链接到此页面时，我收到异常:

Last cause: org.apache.wicket.markup.head.HeaderItem
WicketMessage: Can't instantiate page using constructor 'public kz.company.myPackage.controller.StateDB()'. Might be it doesn't exist, may be it is not visible (public).

但是正如你所看到的，我的类的构造函数是公共(public)的

public StateDB() {

有堆栈跟踪

Complete stack:

org.apache.wicket.WicketRuntimeException: Can't instantiate page using constructor 'public kz.company.myPackage.controller.StateDB()'. Might be it doesn't exist, may be it is not visible (public).
     at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:196)
     at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:68)
     at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:47)
     at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:103)
     at org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:264)
     at org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
     at org.apache.wicket.request.handler.render.PageRenderer.getPage(PageRenderer.java:78)
     at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:105)
     at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:224)
     at org.apache.wicket.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:167)
     at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:784)
     at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
     at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:255)
     at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:212)
     at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:283)
     at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:188)

java.lang.reflect.InvocationTargetException
     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
     at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
     at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
     at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:177)
     at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:68)
     at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:47)
     at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:103)
     at org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:264)
     at org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
     at org.apache.wicket.request.handler.render.PageRenderer.getPage(PageRenderer.java:78)
     at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:105)
     at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:224)
     at org.apache.wicket.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:167)
     at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:784)
     at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
     at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:255)
     at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:212)
     at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:283)
     at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:188)

java.lang.NoClassDefFoundError: org/apache/wicket/markup/head/HeaderItem
     at kz.company.myPackage.controller.StateDB.<init>(StateDB.java:72)
     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
     at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
     at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:177)
     at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:68)
     at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:47)
     at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:103)
     at org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:264)
     at org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
     at org.apache.wicket.request.handler.render.PageRenderer.getPage(PageRenderer.java:78)
     at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:105)
     at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:224)
     at org.apache.wicket.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:167)
     at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:784)
     at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
     at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:255)
     at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:212)
     at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:283)
     at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:188)

Answer 1

你的构造函数出了问题。当构造函数中抛出异常时，Wicket 会捕获它并显示该消息。 “日期”字段有 getter 和 setter 吗？这些是 DateTextField 中的 PropertyModel 所必需的。