这个范例说明如何用JFreeChart画简单的柱状图，下面是一个JSP的简单范例：
<%@ page contentType="text/html; charset=GB2312" %>
<%@ page import="java.awt.*, java.text.*, java.util.*" %>
<%@ page import="org.jfree.chart.*" %>
<%@ page import="org.jfree.chart.axis.*" %>
<%@ page import="org.jfree.chart.labels.StandardCategoryItemLabelGenerator" %>
<%@ page import="org.jfree.chart.plot.*" %>
<%@ page import="org.jfree.chart.renderer.*" %>
<%@ page import="org.jfree.chart.servlet.ServletUtilities" %>
<%@ page import="org.jfree.data.DefaultCategoryDataset" %>
<%@ page import="org.jfree.ui.TextAnchor" %>
<%
//The data for the bar chart
double[] data = 
{85, 156, 179.5, 211, 123};
//The labels for the bar chart
String[] labels = {"Mon", "Tue", "Wed", "Thu", "Fri"};
DefaultCategoryDataset dataset = new DefaultCategoryDataset();
for (int i = 0; i < data.length; i++) {
dataset.addValue(data[i], null, labels[i]);
}
JFreeChart chart = ChartFactory.createBarChart3D("Weekly Server Load", "Work Week 25", "MBytes", dataset, PlotOrientation.VERTICAL, false, false, false);
chart.setBackgroundPaint(new Color(0xE1E1E1));
CategoryPlot plot = chart.getCategoryPlot();
// 设置Y轴显示整数
NumberAxis rangeAxis = (NumberAxis) plot.getRangeAxis();
rangeAxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
CategoryAxis domainAxis = plot.getDomainAxis();
//设置距离图片左端距离
domainAxis.setLowerMargin(0.05);
BarRenderer3D renderer = new BarRenderer3D();
//设置柱的颜色
renderer.setSeriesPaint(0, new Color(0xff00));
plot.setRenderer(renderer);
String filename = ServletUtilities.saveChartAsPNG(chart, 300, 280, null, session);
String graphURL = request.getContextPath() + "/displayChart?filename=" + filename;
%>
<html>
<body topmargin="5" leftmargin="5" rightmargin="0">
<div style="font-size:18pt; font-family:verdana; font-weight:bold">
3D Bar Chart
</div>
<br>
<img src="<%= graphURL %>" border=0>
</body>
</html>
画出来的图：
和ChartDirector画出来的图做一个比较：
posted on 2005-06-14 18:40
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