6

我正在尝试通过简单的视图在 RCP 应用程序中使用 JFreeChart。我将 JfreeChart jar 文件添加为项目的引用库。

由于错误，无法创建视图：

Could not create the view: Plug-in "ViewJFreeChart" was unable to instantiate class "viewJFreeChart.View".
java.lang.NoClassDefFoundError: org/jfree/data/general/PieDataset
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
    at java.lang.Class.getConstructor0(Unknown Source)
    at java.lang.Class.newInstance0(Unknown Source)
    at java.lang.Class.newInstance(Unknown Source)

……

这是 View.java 的源代码：

package viewJFreeChart;

import java.awt.Font;

import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.ITableLabelProvider;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.ISharedImages;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.part.ViewPart;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PiePlot;
import org.jfree.data.general.DefaultPieDataset;
import org.jfree.data.general.PieDataset;
import org.jfree.experimental.chart.swt.ChartComposite;

public class View extends ViewPart {
    public static final String ID = "ViewJFreeChart.view";

    private TableViewer viewer;

    /**
     * This is a callback that will allow us to create the viewer and initialize
     * it.
     */
    public void createPartControl(Composite parent) {

        JFreeChart chart = createChart(createDataset());
        final ChartComposite frame = new ChartComposite(parent, SWT.NONE,
                chart, true);
    }

    /**
     * Passing the focus request to the viewer's control.
     */
    public void setFocus() {
        viewer.getControl().setFocus();
    }

    /**
     * Creates the Dataset for the Pie chart
     */
    private PieDataset createDataset() {
        DefaultPieDataset dataset = new DefaultPieDataset();
        dataset.setValue("One", new Double(43.2));
        dataset.setValue("Two", new Double(10.0));
        dataset.setValue("Three", new Double(27.5));
        dataset.setValue("Four", new Double(17.5));
        dataset.setValue("Five", new Double(11.0));
        dataset.setValue("Six", new Double(19.4));
        return dataset;
    }

    /**
     * Creates the Chart based on a dataset
     */
    private JFreeChart createChart(PieDataset dataset) {

        JFreeChart chart = ChartFactory.createPieChart("Pie Chart Demo 1", // chart
                // title
                dataset, // data
                true, // include legend
                true, false);

        PiePlot plot = (PiePlot) chart.getPlot();
        plot.setSectionOutlinesVisible(false);
        plot.setLabelFont(new Font("SansSerif", Font.PLAIN, 12));
        plot.setNoDataMessage("No data available");
        plot.setCircular(false);
        plot.setLabelGap(0.02);
        return chart;

    }
}
4

1 回答 1

7

当您说您将依赖项添加为引用库时，我假设您的意思是您通过项目属性的Java 构建路径部分将其作为 jar 依赖项添加到 Eclipse 项目，这仅适用于您的工作区中的编译。RCP 需要在 Manifest 中定义依赖项/嵌套 jar，以便在目标平台中解析它们。

要设置插件依赖项，请打开您的 Manifest 文件，您应该会看到一个多选项卡式编辑器。选择Dependencies选项卡并单击Add...，选择插件，然后单击 OK。

依赖项选项卡屏幕截图

如果您选择在插件中捆绑 jar，则需要将其添加到 Manifest 的类路径中。假设 jar 位于插件项目的子目录中，选择Manifest 编辑器的Runtime选项卡，然后选择Classpath部分的Add...按钮。添加罐子并确定。

于 2009-10-02T08:30:53.393 回答