JFreeChart Bar Chart（柱状图）

import java.io.File;   
import java.io.FileNotFoundException;   
import java.io.FileOutputStream;   
import java.io.IOException;   

import org.jfree.chart.ChartFactory;   
import org.jfree.chart.ChartUtilities;   
import org.jfree.chart.JFreeChart;   
import org.jfree.chart.plot.CategoryPlot;   
import org.jfree.chart.plot.PlotOrientation;   
import org.jfree.data.category.CategoryDataset;   
import org.jfree.data.general.DatasetUtilities;   

//JFreeChart Bar Chart（柱状图）   
public class CreateJFreeChartBar {   

    /**  
     * 创建JFreeChart Bar Chart（柱状图）  
     */  
    public static void main(String[] args) {   
        //步骤1：创建CategoryDataset对象（准备数据）   
        CategoryDataset dataset = createDataset();   
        //步骤2：根据Dataset 生成JFreeChart对象，以及做相应的设置   
        JFreeChart freeChart = createChart(dataset);   
        //步骤3：将JFreeChart对象输出到文件，Servlet输出流等   
        saveAsFile(freeChart, "c:\\jfreechart\\bar.png", 500, 400);   
    }   

    //保存为文件   
    public static void saveAsFile(JFreeChart chart, String outputPath, int weight, int height) {   
        FileOutputStream out = null;   
        try {   
            File outFile = new File(outputPath);   
            if (!outFile.getParentFile().exists()) {   
                outFile.getParentFile().mkdirs();   
            }   
            out = new FileOutputStream(outputPath);   
            //保存为PNG文件   
            ChartUtilities.writeChartAsPNG(out, chart, 300, 200);   
            //保存为JPEG文件   
            //ChartUtilities.writeChartAsJPEG(out, chart, 500, 400);   
            out.flush();   
        } catch (FileNotFoundException e) {   
            e.printStackTrace();   
        } catch (IOException e) {   
            e.printStackTrace();   
        } finally {   
            if (out != null) {   
                try {   
                    out.close();   
                } catch (IOException e) {   
                    //do nothing   
                }   
            }   
        }   
    }   

    //根据CategoryDataset生成JFreeChart对象   
    public static JFreeChart createChart(CategoryDataset categoryDataset) {   
        JFreeChart jfreechart = ChartFactory.createBarChart("Bar Chart Demo",    //标题   
                "产品",    //categoryAxisLabel （category轴，横轴，X轴的标签）   
                "数量",    //valueAxisLabel（value轴，纵轴，Y轴的标签）   
                categoryDataset, // dataset   
                PlotOrientation.VERTICAL,   
                true, // legend   
                false, // tooltips   
                false); // URLs   

        //以下的设置可以由用户定制，也可以省略   
        CategoryPlot  plot = (CategoryPlot) jfreechart.getPlot();   
        //背景色　透明度   
        plot.setBackgroundAlpha(0.5f);   
        //前景色　透明度   
        plot.setForegroundAlpha(0.5f);   
        //其它设置可以参考 CategoryPlot   

        return jfreechart;   
    }   

    /**  
     * 创建CategoryDataset对象  
     *   
     */  
    public static CategoryDataset createDataset() {   

        String []rowKeys = {"One", "Two", "Three"};   
        String []colKeys = {"1987", "1997", "2007"};   

        double [][] data = {   
                {50, 20, 30},   
                {20, 10D, 40D},   
                {40, 30.0008D, 38.24D},   
        };   

        //也可以使用以下代码   
        //DefaultCategoryDataset categoryDataset = new DefaultCategoryDataset();   
        //categoryDataset.addValue(10, "rowKey", "colKey");   

        return DatasetUtilities.createCategoryDataset(rowKeys, colKeys, data);           
    }   

}