我正在尝试使用Batik库将BufferedImage绘制为SVG文件。我有非常相似的代码可以很好地处理EPS/PS文件，但是出于某些原因，以下代码:
// Get a DOMImplementation and create an XML document
DOMImplementation domImpl = GenericDOMImplementation.getDOMImplementation();
Document document = domImpl.createDocument(null, "svg", null);
// Create an instance of the SVG Generator
SVGGraphics2D svgGenerator = new SVGGraphics2D(document);
// draw from image into the svg:
svgGenerator.drawImage(image,new RescaleOp((float)1.0,(float)0.0,null),0,0);
// Write svg file
OutputStream outputStream = new FileOutputStream(svgFile);
Writer out = new OutputStreamWriter(outputStream, "UTF-8");
//svgGenerator.stream(out, true /* use css */);
// write and close file:
outputStream.flush();
outputStream.close();
在svgGenerator.drawImage(...)行上导致NullPointerException。由于基本上相同的命令适用于AbstractPSDocumentGraphics2D(在另一种方法中)，所以我不知道这里出了什么问题。
编辑:
image在其他地方声明(一个类变量，此代码在该类的方法内部)。
这是一个堆栈跟踪:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at org.apache.batik.svggen.ImageHandlerBase64Encoder.encodeImage(ImageHandlerBase64Encoder.java:157)
at org.apache.batik.svggen.ImageHandlerBase64Encoder.handleHREF(ImageHandlerBase64Encoder.java:133)
at org.apache.batik.svggen.ImageHandlerBase64Encoder.handleHREF(ImageHandlerBase64Encoder.java:72)
at org.apache.batik.svggen.DefaultImageHandler.handleImage(DefaultImageHandler.java:63)
at org.apache.batik.svggen.SimpleImageHandler.handleImage(SimpleImageHandler.java:100)
at org.apache.batik.svggen.SVGGraphics2D.drawImage(SVGGraphics2D.java:677)
at org.apache.batik.svggen.SVGGraphics2D.drawImage(SVGGraphics2D.java:996)
at SciTK.SciTK_Image.exportImageAsSVG(SciTK_Image.java:1232)
at SciTK.SciTK_Image.save_image(SciTK_Image.java:428)
at SciTK.SciTK_Image$7.actionPerformed(SciTK_Image.java:982)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
at com.apple.laf.AquaMenuItemUI.doClick(AquaMenuItemUI.java:157)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:688)
at java.awt.EventQueue$3.run(EventQueue.java:686)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:702)
at java.awt.EventQueue$4.run(EventQueue.java:700)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
最佳答案
为了其他人在谷歌上搜索...我有-我相信-同样的问题。
假设 batik 1.7:底层原因是:ImageHandlerBase64Encoder.encodeImage()调用:
ImageWriter writer = ImageWriterRegistry.getInstance().getWriterFor("image/png");
writer.writeImage(buf, os);
并且
ImageWriterRegistry为空，因此它从getWriterFor("image/png")返回null，因此writer.writeImage(buf, os);死亡。注册表为空的原因是类路径中缺少JAR。我认为
batik-codec.jar是特别需要的，但是我刚刚添加了所有的 batik JAR。您可以下载 batik 资源，并在调试器中看到，使用JAR会注册“image/png”和其他格式(对
ImageWriterRegistry.getInstance()的第一次调用创建了实例，其构造函数调用了setup()，后者依次遍历所有ImageWriter服务提供者-应该是具有正确Classpath的非空集。)