java - 尝试在 Wicket 口中写入响应时出现 IndexOutOfBoundException

Question

我有一个像这样的 Wicket 页面:

public final class Services extends WebPage {
    public Services() {
        super();   
    }

    public Services(PageParameters params) {
        StringValue serviceType = params.get("name");
        if("report".equals(serviceType.toString())) {
            this.getResponse().write("HelloWorld");
        }
    }
}

并且它的 html 是空的。当我调用此页面的 URL 时，我看到此错误

Index: 0, Size: 0
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
    at java.util.ArrayList.rangeCheck(ArrayList.java:604)
    at java.util.ArrayList.get(ArrayList.java:382)
    at java.util.Collections$UnmodifiableList.get(Collections.java:1211)
    at org.apache.wicket.markup.Markup.get(Markup.java:130)
    at org.apache.wicket.Component.internalRender(Component.java:2356)
    at org.apache.wicket.Component.render(Component.java:2307)
    at org.apache.wicket.Page.renderPage(Page.java:1010)
    at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:121)
    at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:271)
    at org.apache.wicket.core.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:165)
    at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:861)
    at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
    at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:261)
    at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:218)
    at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:289)
    at org.apache.wicket.protocol.http.WicketFilter.processRequestCycle(WicketFilter.java:259)
    at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:201)
    at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:282)
...

我真的不知道我的简单 Wicket 页面出了什么问题。

Answer 1

Wicket 期望在代码的关联 HTML 模板中添加一些标记。异常发起者的行位于 Component.class 中，请参阅

private final void internalRender()
{
...
    MarkupElement elem = markup.get(0);
...
}

该代码获取关联标记的“根”元素。没有任何标记的代码在 Wicket 中是无意义的。

提示:如果您只想处理请求，请安装可共享资源或页面以外的一些其他资源。