Java和RequestHandler -如何？

Question

使用场景:用户点击网站上的链接，就会得到两种语言的动态PDF :德语和英语。

这个密码起作用了。generateCouponPdfOnClick创建一个包含pdf文件的ResourceStreamRequestHandler。

Link<Void> generatePdf = new Link<Void>("generatePdf") {
@Override
public void onClick() {
    ResourceStreamRequestHandler requestHandler = generateCouponPdfOnClick(coupon, PDFLanguage.GERMAN);
    getRequestCycle().scheduleRequestHandlerAfterCurrent(requestHandler);
}
};

现在，我想修改代码以获得一个弹出窗口(Wicket，这里是PdfDialogPage类)，用户可以通过在这两个按钮中的一个按钮上单击，为PDF选择一种语言(德语/英语)。如果用户单击某个按钮，则ModalWindow应关闭，并应生成并显示PDF。

下面是修改后的代码:变量pdflanguageanguage包含所选语言，并由PdfDialogPage使用PageReferenz设置

AjaxLink<Void> generatePdf = new AjaxLink<Void>("generatePdf") {
@Override
public void onClick(final AjaxRequestTarget target) {
    modalWindow.setPageCreator(() -> {
        return new PdfDialogPage(getPage().getPageReference(), modalWindow);
    });
    modalWindow.setWindowClosedCallback((AjaxRequestTarget target1) -> {
        ResourceStreamRequestHandler requestHandler = generateCouponPdfOnClick(coupon, pdflanguageanguage);
        getRequestCycle().scheduleRequestHandlerAfterCurrent(requestHandler);
    });
    modalWindow.show(target);
};

当我单击该链接时，将打开modalwindow。我选择语言，例如英语，modalWindow在将" English“写到变量pdflanguageanguage时关闭。比什么都没有发生..。并且不生成PDF。Wicket窗口告诉我文件夹日志：

</head>]]></header-contribution><evaluate><![CDATA[(function(){var settings = {"minWidth":200,"minHeight":200,"className":"w_blue","width":400,"height":100,"resizable":true,"src":"./wicket/page?6","mask":"semi-transparent","autoSize":false,"unloadConfirmation":true,"onClose":function() { Wicket.Ajax.ajax({"u":"./overviewCoupons?5-1.1-panel-modalWindow","c":"modalWindowb0"}); },"onCloseButton":function() { Wicket.Ajax.ajax({"u":"./overviewCoupons?5-1.0-panel-modalWindow","c":"modalWindowb0"});; return false; }};window.setTimeout(function(){
  Wicket.Window.create(settings).show();
}, 0);
})();]]></evaluate></ajax-response>
INFO: returned focused element: javascript:;
INFO: returned focused element: javascript:;
INFO: Response processed successfully.
INFO: refocus last focused component not needed/allowed
INFO: focus removed from generatePdf5
INFO: focus set on _wicket_window_3
INFO: focus set on undefined
INFO: focus removed from undefined

错误: Wicket.Ajax.Call.failure:解析响应时出错:错误:无效XML：%PDF-1.4 %����

1 0 obj
<<
/Creator (Apache FOP Version 2.3)
/Producer (Apache FOP Version 2.3)
/CreationDate (D:20180808160110+02'00')

我相信Ajax和"getRequestCycle().scheduleRequestHandlerAfterCurrent(requestHandler);".之间存在一个问题。我该怎么用这些。因此，我将代码简化为：

AjaxLink<Void> generatePdf = new AjaxLink<Void>("generatePdf") {
@Override
public void onClick(final AjaxRequestTarget target) {
ResourceStreamRequestHandler requestHandler = generateCouponPdfOnClick(coupon, PDFLanguage.ENGLISH);
getRequestCycle().scheduleRequestHandlerAfterCurrent(requestHandler);
}
};

当我知道单击AjaxLink时，什么都不会发生，但我会得到相同的Ajax错误输出。

如何将AjaxLink与ResourceStreamRequestHandler结合使用？

Answer 1

我用这种方式解决了一个类似的用例。

您需要来自这里的Java类这里

或者，您可以使用我的变体，它以一个FileResourceStream作为输入。

import lombok.extern.slf4j.Slf4j;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.behavior.AbstractAjaxBehavior;
import org.apache.wicket.request.handler.resource.ResourceStreamRequestHandler;
import org.apache.wicket.request.resource.ContentDisposition;
import org.apache.wicket.util.resource.FileResourceStream;

/**
 * @author Sven Meier
 * @author Ernesto Reinaldo Barreiro (reiern70@gmail.com)
 * @author Jordi Deu-Pons (jordi@jordeu.net)
 */
@Slf4j
public class AJAXDownload extends AbstractAjaxBehavior {

    private boolean addAntiCache;
    private FileResourceStream fileResourceStream;
    private String fileName;

    public AJAXDownload() {
        this(true);
    }

    public AJAXDownload(boolean addAntiCache) {
        super();
        this.addAntiCache = addAntiCache;
    }

    /**
     * Call this method to initiate the download.
     */
    public void initiate(AjaxRequestTarget target, FileResourceStream fileResourceStream, String fileName) {
        this.fileResourceStream= fileResourceStream;
        this.fileName = fileName;
        String url = getCallbackUrl().toString();

        if (addAntiCache) {
            url = url + (url.contains("?") ? "&" : "?");
            url = url + "antiCache=" + System.currentTimeMillis();
        }

        // the timeout is needed to let Wicket release the channel
        target.appendJavaScript("setTimeout(\"window.location.href='" + url + "'\", 100);");
    }

    public void onRequest() {
        try{
            ResourceStreamRequestHandler handler = new ResourceStreamRequestHandler(fileResourceStream, fileName);
            handler.setContentDisposition(ContentDisposition.ATTACHMENT);
            getComponent().getRequestCycle().scheduleRequestHandlerAfterCurrent(handler);
        } catch (Exception e){
            log.error("Error while trying to download", e);
            onErrorOccurred();
        }
    }
    protected void onErrorOccurred(){}
}

如何使用？

1. 必须将AjaxDownload添加到表单中。 form.add(ajaxDownload =新AJAXDownload())；
2. 在您的onSubmit中，您可以从AjaxLink调用： 文件yourPdfFile =//创建您的pdf文件；最终FileResourceStream resourceStream=新FileResourceStream(yourPdfFile)；ajaxDownload.initiate(目标，resourceStream，"yourPDF.pdf")；