显示数据库中的图像。获取net.sf.jasperreports.engine.jrexception：读取图像失败

Question

net.sf.jasperreports.engine.JRException: net.sf.jasperreports.engine.JRException: Unable to get value for field 'Attr1_icon' of class 'java.awt.Image'
at com.jaspersoft.studio.editor.preview.view.control.ReportControler.fillReport(ReportControler.java:482)
at com.jaspersoft.studio.editor.preview.view.control.ReportControler.access$18(ReportControler.java:457)
at com.jaspersoft.studio.editor.preview.view.control.ReportControler$4.run(ReportControler.java:347)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)
Caused by: net.sf.jasperreports.engine.JRException: Unable to get value for field 'Attr1_icon' of class 'java.awt.Image'
at net.sf.jasperreports.engine.JRResultSetDataSource.getFieldValue(JRResultSetDataSource.java:319)
at net.sf.jasperreports.engine.fill.JRFillDataset.setOldValues(JRFillDataset.java:1356)
at net.sf.jasperreports.engine.fill.JRFillDataset.next(JRFillDataset.java:1257)
at net.sf.jasperreports.engine.fill.JRFillDataset.next(JRFillDataset.java:1233)
at net.sf.jasperreports.engine.fill.JRBaseFiller.next(JRBaseFiller.java:1577)
at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:149)
at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:932)
at net.sf.jasperreports.engine.fill.BaseFillHandle$ReportFiller.run(BaseFillHandle.java:120)
at java.lang.Thread.run(Unknown Source)
Caused by: net.sf.jasperreports.engine.JRException: Image read failed.
at net.sf.jasperreports.engine.util.JRJdk14ImageReader.readImage(JRJdk14ImageReader.java:73)
at net.sf.jasperreports.engine.util.JRImageLoader.loadAwtImageFromBytes(JRImageLoader.java:167)
at net.sf.jasperreports.engine.JRResultSetDataSource.getFieldValue(JRResultSetDataSource.java:309)
Caused by: net.sf.jasperreports.engine.JRException: Image read failed.
at net.sf.jasperreports.engine.util.JRJdk14ImageReader.readImage(JRJdk14ImageReader.java:73)
at net.sf.jasperreports.engine.util.JRImageLoader.loadAwtImageFromBytes(JRImageLoader.java:167)
at net.sf.jasperreports.engine.JRResultSetDataSource.getFieldValue(JRResultSetDataSource.java:309)

public Image readImage(byte[] bytes) throws JRException {
    InputStream bais = new ByteArrayInputStream(bytes);

    Image image = null;
    try {
        image = ImageIO.read(bais);
    } catch (Exception e) {
        throw new JRException(e);
    } finally {
        try {
            bais.close();
        } catch (IOException e) {
        }
    }

    if (image == null) {
        throw new JRException("Image read failed."); // Line 73
    }

    return image;
}

Returns a BufferedImage as the result of decoding a supplied InputStream with an
ImageReader chosen automatically from among those currently registered. The InputStream
is wrapped in an ImageInputStream. If no registered ImageReader claims to be able to
read the resulting stream, null is returned.

所以我猜没有注册的ImageReader？我怎么能通过Jaspersoft Studio修复这样的东西？

编辑：我尝试使用java.io.InputStream作为这里建议的类类型，但结果是相同的错误。算是吧。一个很大的区别是，在Jaspersoft Studio中，如果出现错误，您可以将图像设置为显示为空白。如果我使用java.awt.Image，那么这个设置什么也不做。我仍然得到一个错误，报告不能建立。如果我使用java.io.InputStream，报告确实会生成，但是图像是空白的。如果打开错误报告，我会得到类似的堆栈跟踪，但并不完全相同：

net.sf.jasperreports.engine.JRRuntimeException: net.sf.jasperreports.engine.JRException: Image read failed.
at net.sf.jasperreports.engine.export.draw.PrintDrawVisitor.visit(PrintDrawVisitor.java:143)
at net.sf.jasperreports.engine.export.draw.PrintDrawVisitor.visit(PrintDrawVisitor.java:1)
at net.sf.jasperreports.engine.fill.JRTemplatePrintImage.accept(JRTemplatePrintImage.java:451)
at net.sf.jasperreports.engine.export.draw.FrameDrawer.draw(FrameDrawer.java:251)
at net.sf.jasperreports.engine.export.draw.FrameDrawer.draw(FrameDrawer.java:199)
at net.sf.jasperreports.engine.export.JRGraphics2DExporter.exportPage(JRGraphics2DExporter.java:273)
at net.sf.jasperreports.engine.export.JRGraphics2DExporter.exportReportToGraphics2D(JRGraphics2DExporter.java:246)
at net.sf.jasperreports.engine.export.JRGraphics2DExporter.exportReport(JRGraphics2DExporter.java:184)
at net.sf.jasperreports.eclipse.viewer.ViewerCanvas.renderPage(ViewerCanvas.java:369)
at net.sf.jasperreports.eclipse.viewer.ViewerCanvas.refresh(ViewerCanvas.java:344)
at net.sf.jasperreports.eclipse.viewer.ViewerCanvas$2.viewerStateChanged(ViewerCanvas.java:118)
at net.sf.jasperreports.eclipse.viewer.ReportViewer.fireViewerModelChanged(ReportViewer.java:383)
at net.sf.jasperreports.eclipse.viewer.ReportViewer.setPageIndex(ReportViewer.java:297)
at com.jaspersoft.studio.editor.preview.view.report.swt.SWTViewer.setJRPRint(SWTViewer.java:125)
at com.jaspersoft.studio.editor.preview.view.report.swt.SWTViewer.setJRPRint(SWTViewer.java:112)
at com.jaspersoft.studio.editor.preview.PreviewJRPrint.switchRightView(PreviewJRPrint.java:226)
at com.jaspersoft.studio.editor.preview.PreviewContainer.switchRightView(PreviewContainer.java:247)
at com.jaspersoft.studio.editor.preview.PreviewJRPrint$3.switchView(PreviewJRPrint.java:194)
at com.jaspersoft.studio.editor.preview.PreviewJRPrint$1.run(PreviewJRPrint.java:153)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4144)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3761)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2701)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2665)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2499)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:679)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:668)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at com.jaspersoft.studio.rcp.intro.Application.start(Application.java:97)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
Caused by: net.sf.jasperreports.engine.JRException: Image read failed.
at net.sf.jasperreports.engine.util.JRJdk14ImageReader.readImage(JRJdk14ImageReader.java:73)
at net.sf.jasperreports.engine.util.JRImageLoader.loadAwtImageFromBytes(JRImageLoader.java:167)
at net.sf.jasperreports.engine.JRImageRenderer.getImage(JRImageRenderer.java:407)
at net.sf.jasperreports.engine.JRImageRenderer.getDimension(JRImageRenderer.java:482)
at net.sf.jasperreports.engine.RenderableUtil.getOnErrorRendererForDimension(RenderableUtil.java:264)
at net.sf.jasperreports.engine.export.draw.ImageDrawer.draw(ImageDrawer.java:116)
at net.sf.jasperreports.engine.export.draw.PrintDrawVisitor.visit(PrintDrawVisitor.java:134)

但是，正如您所看到的，根本原因仍然来自JRJDK14ImageReader.java第73行。

同样，对于我尝试的表达式javax.imageio.imageio.read($F{Attr1_icon}），这实际上不会产生任何错误，但图像是空白的。

Answer 1

尽管我在本期文章中发布了它，但我完全忽略了这样一个事实，即图像是Base64编码的，这意味着它是一个字符串。因此，Jasper不能使用该值，因此必须对其进行解码。这可以通过以下两种方法之一实现：

将表达式更改为：

new java.io.ByteArrayInputStream(javax.xml.DatatypeConverter.parseBase64Binary($F{ImageField}))

或者简单地将字符串转换为数据库中的二进制。在Sybase中，这是base64_decode函数。一旦它被转换，您只需将类型更改为java.io.InputStream，它就可以工作了。