Question

ireport+jasperreport生成bar chart问题

生成的柱状图如何控制柱子的宽度（不是整个报表的宽度，是每个柱子的宽度）
另外，怎么不让category expression出现省略号...如图

Answer 1

开源的jfreechart，你可以看看。
官方demo
/* ===========================================================
* JFreeChart : a free chart library for the Java(tm) platform
* ===========================================================
*
* (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
*
* Project Info:
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* ---------------------
* SWTBarChartDemo1.java
* ---------------------
* (C) Copyright 2006-2008, by Object Refinery Limited and Contributors.
*
* Original Author: David Gilbert (for Object Refinery Limited);
* Contributor(s): Henry Proudhon (henry.proudhon AT ensmp.fr).
*
* Changes
* -------
* 23-Aug-2006 : New class (DG);
*
*/

package org.jfree.experimental.chart.swt.demo;

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.axis.CategoryLabelPositions;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.renderer.category.BarRenderer;
import org.jfree.chart.renderer.category.StandardBarPainter;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.experimental.chart.swt.ChartComposite;

/**
* An SWT demo.
*/
public class SWTBarChartDemo1 {

/**
* Returns a sample dataset.
*
* @return The dataset.
*/
private static CategoryDataset createDataset() {

// row keys...
String series1 = "First";
String series2 = "Second";
String series3 = "Third";

// column keys...
String category1 = "Category 1";
String category2 = "Category 2";
String category3 = "Category 3";
String category4 = "Category 4";
String category5 = "Category 5";

// create the dataset...
DefaultCategoryDataset dataset = new DefaultCategoryDataset();

dataset.addValue(1.0, series1, category1);
dataset.addValue(4.0, series1, category2);
dataset.addValue(3.0, series1, category3);
dataset.addValue(5.0, series1, category4);
dataset.addValue(5.0, series1, category5);

dataset.addValue(5.0, series2, category1);
dataset.addValue(7.0, series2, category2);
dataset.addValue(6.0, series2, category3);
dataset.addValue(8.0, series2, category4);
dataset.addValue(4.0, series2, category5);

dataset.addValue(4.0, series3, category1);
dataset.addValue(3.0, series3, category2);
dataset.addValue(2.0, series3, category3);
dataset.addValue(3.0, series3, category4);
dataset.addValue(6.0, series3, category5);

return dataset;

}

/**
* Creates a sample chart.
*
* @param dataset the dataset.
*
* @return The chart.
*/
private static JFreeChart createChart(CategoryDataset dataset) {

// create the chart...
JFreeChart chart = ChartFactory.createBarChart(
"SWTBarChartDemo1", // chart title
"Category", // domain axis label
"Value", // range axis label
dataset, // data
PlotOrientation.VERTICAL, // orientation
true, // include legend
true, // tooltips?
false // URLs?
);

// NOW DO SOME OPTIONAL CUSTOMISATION OF THE CHART...

// get a reference to the plot for further customisation...
CategoryPlot plot = (CategoryPlot) chart.getPlot();

// set the range axis to display integers only...
NumberAxis rangeAxis = (NumberAxis) plot.getRangeAxis();
rangeAxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());

// disable bar outlines...
BarRenderer renderer = (BarRenderer) plot.getRenderer();
renderer.setDrawBarOutline(false);

// the SWTGraphics2D class doesn't handle GradientPaint well, so
// replace the gradient painter from the default theme with a
// standard painter...
renderer.setBarPainter(new StandardBarPainter());

CategoryAxis domainAxis = plot.getDomainAxis();
domainAxis.setCategoryLabelPositions(
CategoryLabelPositions.createUpRotationLabelPositions(
Math.PI / 6.0));
// OPTIONAL CUSTOMISATION COMPLETED.

return chart;

}

/**
* Starting point for the demonstration application.
*
* @param args ignored.
*/
public static void main(String[] args) {
JFreeChart chart = createChart(createDataset());
Display display = new Display();
Shell shell = new Shell(display);
shell.setSize(600, 300);
shell.setLayout(new FillLayout());
shell.setText("Test for jfreechart running with SWT");
ChartComposite frame = new ChartComposite(shell, SWT.NONE, chart,
true);
frame.pack();
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch())
display.sleep();
}
}

}
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