如何让 Apache FOP 的 PreviewDialog 真正显示我的文档？

Question

尽管我进行了搜索，但我还没有找到解决我的问题的方法，我希望 StackOverflow 的共同思想能够将我推向正确的方向。

我的问题如下，我正在开发消息系统用户代理的打印和打印预览部分。我获得了特定的 XSLT 模板，这些模板在转换 XML 后将生成一个格式化对象文档。使用 Apache FOP，我已经能够将 FO 文档呈现为 PDF，这一切都很好，但我还想在打印预览对话框中显示它。 Apache FOP 包含一个名为 PreviewDialog 的类，该类在其构造函数中需要一个我可以生成的 FOUserAgent 以及一个实现 Renderable 接口的对象。

Renderable 接口在 FOP 包中有一个实现类，称为 InputHandler，它在其构造函数中接受一个标准 io File 对象。现在麻烦就从这里开始了。我当前将 FO 文档存储为临时文件，并将其作为 File 对象传递给 InputHandler 实例，然后将其传递给 PreviewDialog >。我看到屏幕上出现该对话框，状态栏底部显示它正在生成文档，这就是它所做的一切。

这是我尝试使用的代码。它不是生产代码，因此不太漂亮：

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.sax.SAXResult;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

import org.apache.fop.apps.FOPException;
import org.apache.fop.apps.FOUserAgent;
import org.apache.fop.apps.Fop;
import org.apache.fop.apps.FopFactory;
import org.apache.fop.cli.InputHandler;
import org.apache.fop.render.awt.viewer.PreviewDialog;

public class PrintPreview {

    public void showPreview(final File xslt, final File xmlSource) {
        boolean err = false;
        OutputStream out = null;
        Transformer transformer = null;

        final String tempFileName = this.getTempDir()
                + this.generateTempFileName();
        final String tempFoFile = tempFileName + ".fo";
        final String tempPdfFile = tempFileName + ".pdf";
        System.out.println(tempFileName);

        final TransformerFactory transformFactory = TransformerFactory
                .newInstance();
        final FopFactory fopFactory = FopFactory.newInstance();

        try {
            transformer = transformFactory
                    .newTransformer(new StreamSource(xslt));
            final Source src = new StreamSource(xmlSource);
            out = new FileOutputStream(tempFoFile);
            final Result res = new StreamResult(out);

            transformer.transform(src, res);
            System.out.println("XSLT Transform Completed");
        } catch (final TransformerConfigurationException e) {
            err = true;
            e.printStackTrace();
        } catch (final FileNotFoundException e) {
            err = true;
            e.printStackTrace();
        } catch (final TransformerException e) {
            err = true;
            e.printStackTrace();
        } finally {
            if (out != null) {
                try {
                    out.close();
                } catch (final IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }

        System.out.println("Initializing Preview");
        transformer = null;
        out = null;
        final File fo = new File(tempFoFile);
        final File pdf = new File(tempPdfFile);

        if (!err) {

            final FOUserAgent ua = fopFactory.newFOUserAgent();
            try {
                transformer = transformFactory.newTransformer();
                out = new FileOutputStream(pdf);
                out = new BufferedOutputStream(out);

                final Fop fop = fopFactory.newFop(
                        MimeConstants.MIME_PDF, ua,
                            out);

                final Source foSrc = new StreamSource(fo);
                final Result foRes = new SAXResult(fop.getDefaultHandler());

                transformer.transform(foSrc, foRes);

                System.out.println("Transformation Complete");

        } catch (final FOPException e) {
            err = true;
            e.printStackTrace();
        } catch (final FileNotFoundException e) {
            err = true;
            e.printStackTrace();
        } catch (final TransformerException e) {
            err = true;
            e.printStackTrace();
        } finally {
            if (out != null) {
                try {
                    out.close();
                } catch (final IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }

        if (!err) {
            System.out.println("Attempting to Preview");
            final InputHandler inputHandler = new InputHandler(fo);

            PreviewDialog.createPreviewDialog(ua, inputHandler, true);
        }
    }

    // perform the clean up
    // f.delete();

}

private String getTempDir() {

    final String p = "java.io.tmpdir";

    return System.getProperty(p);

}

private String generateTempFileName() {
    final String charset = "abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890";
    final StringBuffer sb = new StringBuffer();
    Random r = new Random();
    int seed = r.nextInt();
    r = new Random(seed);
    for (int i = 0; i < 8; i++) {
        final int n = r.nextInt(71);
        seed = r.nextInt();
        sb.append(charset.charAt(n));
        r = new Random(seed);
    }

    return sb.toString();
}

}

对此的任何帮助将不胜感激。

Answer 1

答案似乎是放弃尝试使用 Apache FOP 中的预览对话框，而是使用 Apache PDFBox 使用 PDFPagePanel 类生成打印预览来显示更改。

Answer 2

实际上我没有找到一种漂亮的方法来隐藏 debug 和 fop inf 按钮，它们是
显示在工具栏中。我必须创建自己的 PreviewDialog，主要基于 fop，但没有这两个按钮。

Answer 3

必须在转换为 pdf 之前创建 createPreviewDialog

    FopFactory fopFactory = FopFactory.newInstance();
    FOUserAgent foUserAgent = fopFactory.newFOUserAgent(); 
    AWTRenderer renderer = new AWTRenderer();      
    renderer.setPreviewDialogDisplayed(false);
    foUserAgent.setRendererOverride(renderer);
    renderer.setUserAgent(foUserAgent);
    PreviewDialog previewDlg = PreviewDialog.createPreviewDialog(foUserAgent, null, false);
    renderer.setStatusListener(previewDlg);
    renderer.clearViewportList();

    TransformerFactory transformFactory = TransformerFactory.newInstance();

    Transformer transformerFo = transformFactory.newTransformer(new StreamSource(xslt));
    FileOutputStream fileoutFo = new FileOutputStream(tempFoFile);
    BufferedOutputStream outFo = new BufferedOutputStream(fileoutFo);
    transformerFo.transform (new StreamSource(xml),new StreamResult(outFo));

    Transformer transformerPdf = transformFactory.newTransformer();
    FileOutputStream fileoutPdf = new FileOutputStream(tempPdfFile);
    BufferedOutputStream outPdf = new BufferedOutputStream(fileoutPdf);

    final Fop fop = fopFactory.newFop(MimeConstants.MIME_PDF, 
                                      foUserAgent, outPdf);
    Source srcPdf = new StreamSource(fo);
    Result resPdf = new SAXResult(fop.getDefaultHandler());
    transformerPdf.transform(srcPdf, resPdf);