Question

我正在为Bitbucket Server编写一个插件，其中必须处理将PDF渲染为图像的问题。我为此使用PDFBox。我有一个pdfToPng方法将被调用来进行处理，并且我已经修改了PDF渲染器，类似于Apache示例所建议的。

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.graphics.color.PDColor;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.apache.pdfbox.rendering.PageDrawer;
import org.apache.pdfbox.rendering.PageDrawerParameters;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class PDFProcessor {

    private static Logger logger = LoggerFactory.getLogger(PDFProcessor.class);

    private static int _colorMode;

    /**
     * Convert a page of a PDF document into a colored PNG
     * @param color color to use, 0 - black, 1- red
     * @param fileName output file
     * @param pdfFile PDF to process
     * @throws IOException
     */
    public static void pdfToPng(int color, String fileName, File pdfFile) throws IOException{
        _colorMode = color;
        try (PDDocument pdfDoc = PDDocument.load(pdfFile)){
            logger.info("Begin PDF to PNG render for " + fileName);
            PDFRenderer renderer = new CustomPdfRenderer(pdfDoc);
            BufferedImage image = renderer.renderImageWithDPI(0,600);
            logger.info("Making PNG transparent...");
            BufferedImage transparentImage = ImageProcessor.makeTransparent(image,new Color(image.getRGB(0,0)));
            ImageIO.write(transparentImage, "PNG",new File(fileName+".png"));
            logger.info("Image processed successfully, writing to " + fileName + ".png");
        }
    }

    private static class CustomPdfRenderer extends PDFRenderer{
        CustomPdfRenderer(PDDocument document){
            super(document);
        }

        @Override
        protected PageDrawer createPageDrawer(PageDrawerParameters params) throws IOException{
            return new CustomPageDrawer(params);
        }
    }

    private static class CustomPageDrawer extends PageDrawer{
        CustomPageDrawer(PageDrawerParameters params) throws IOException{
            super(params);
        }

        @Override
        protected Paint getPaint(PDColor color) throws IOException{
            if ((color.toRGB() == (Color.BLACK.getRGB() & 0x00FFFFFF)) && (_colorMode == 1)){
                return Color.RED;
            }
            return super.getPaint(color);
        }
    }
}

该项目是使用Maven构建的，因为这是BitBucket用于插件开发的时候。但是，当实际调用该方法时，我得到一个ClassNotFound异常说明：

[INFO] Caused by: java.lang.NoClassDefFoundError: org/apache/pdfbox/rendering/PDFRenderer
[INFO]  at com.my-plugin.DiffManager.prepareDiff(DiffManager.java:99)
[INFO]  at com.my-plugin.DiffManager.doGet(DiffManager.java:67)
[INFO]  at com.my-plugin.DiffManager.doPost(DiffManager.java:84)
[INFO]  ... 33 common frames omitted
[INFO] Caused by: java.lang.ClassNotFoundException: org.apache.pdfbox.rendering.PDFRenderer not found by com.my-plugin.integrationPlugin [219]
[INFO]  at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1532)
[INFO]  ... 36 common frames omitted

如您所见，我已经导入了PDFRenderer类。我的pom.xml还包含正确的依赖项定义：

<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>2.0.14</version>
    <scope>provided</scope>
</dependency>

为什么Java无法找到PDFRenderer类？以这种方式声明的其他依赖项永远不会出现此问题。

Answer 1

您正在将pdfbox与<scope>provided</scope>的依赖关系使用。您期望谁提供此依赖关系？像Tomcat这样的应用程序容器？

我建议您删除scope行，这样依赖项将隐式为compile范围，这将为您解决问题。

也请咨询Maven scope docs，其中指出：

compile –这是默认范围，如果未指定，则使用该范围。编译依赖项在项目的所有类路径中均可用。
provided –类似于编译，但是表明您希望JDK或容器在运行时提供依赖项。

PDFBox错误：存在时出现“找不到org.apache.pdfbox.rendering.PDFRenderer”

1 个答案: