jFreeChart利用CategoryDatase,ChartFactory.createBarChart生成的柱狀圖

package com.potevio.rnd;

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;

public class CreateJFreeChartBar {

    /**
     * 創建JFreeChart Bar Chart（柱狀圖）
     */
    public static void main(String[] args) {
        //步驟1：創建CategoryDataset對象（准備數據）
        CategoryDataset dataset = createDataset();
        //步驟2：根據Dataset 生成JFreeChart對象，以及做相應的設置
        JFreeChart freeChart = createChart(dataset);
        //步驟3：將JFreeChart對象輸出到文件，Servlet輸出流等
        saveAsFile(freeChart, "F:\\jfreechart\\bar.png", 500, 400);
    }

    //保存為文件
    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);
            //保存為PNG文件
            ChartUtilities.writeChartAsPNG(out, chart, weight, height);
            //保存為JPEG文件
            //ChartUtilities.writeChartAsJPEG(out, chart, weight, height);
            out.flush();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    //do nothing
                }
            }
        }
    }

    //根據CategoryDataset生成JFreeChart對象
    public static JFreeChart createChart(CategoryDataset categoryDataset) {
        JFreeChart jfreechart = ChartFactory.createBarChart("Bar Chart Demo",    //標題
                "產品",    //categoryAxisLabel （category軸，橫軸，X軸的標簽）
                "數量",    //valueAxisLabel（value軸，縱軸，Y軸的標簽）
                categoryDataset, // dataset
                PlotOrientation.VERTICAL,
                true, // legend
                false, // tooltips
                false); // URLs

        //以下的設置可以由用戶定制，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);
        //其它設置可以參考 CategoryPlot

        return jfreechart;
    }

    /**
     * 創建CategoryDataset對象
     *
     */
    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},
        };

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

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

}

package com.potevio.rnd;
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;
public class CreateJFreeChartBar {
/**  
 * 創建JFreeChart Bar Chart（柱狀圖）  
 */  
public static void main(String[] args) {   
    //步驟1：創建CategoryDataset對象（准備數據）   
    CategoryDataset dataset = createDataset();   
    //步驟2：根據Dataset 生成JFreeChart對象，以及做相應的設置   
    JFreeChart freeChart = createChart(dataset);   
    //步驟3：將JFreeChart對象輸出到文件，Servlet輸出流等   
    saveAsFile(freeChart, "F:\\jfreechart\\bar.png", 500, 400);   
}   
   
//保存為文件   
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);   
        //保存為PNG文件   
        ChartUtilities.writeChartAsPNG(out, chart, weight, height);   
        //保存為JPEG文件   
        //ChartUtilities.writeChartAsJPEG(out, chart, weight, height);   
        out.flush();   
    } catch (FileNotFoundException e) {   
        e.printStackTrace();   
    } catch (IOException e) {   
        e.printStackTrace();   
    } finally {   
        if (out != null) {   
            try {   
                out.close();   
            } catch (IOException e) {   
                //do nothing   
            }   
        }   
    }   
}   

//根據CategoryDataset生成JFreeChart對象   
public static JFreeChart createChart(CategoryDataset categoryDataset) {   
    JFreeChart jfreechart = ChartFactory.createBarChart("Bar Chart Demo",    //標題   
            "產品",    //categoryAxisLabel （category軸，橫軸，X軸的標簽）   
            "數量",    //valueAxisLabel（value軸，縱軸，Y軸的標簽）   
            categoryDataset, // dataset   
            PlotOrientation.VERTICAL,   
            true, // legend   
            false, // tooltips   
            false); // URLs   
       
    //以下的設置可以由用戶定制，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);   
    //其它設置可以參考 CategoryPlot   
       
    return jfreechart;   
}   

/**  
 * 創建CategoryDataset對象  
 *   
 */  
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},   
    };   
       
    //也可以使用以下代碼   
    //DefaultCategoryDataset categoryDataset = new DefaultCategoryDataset();   
    //categoryDataset.addValue(10, "rowKey", "colKey");   
       
    return DatasetUtilities.createCategoryDataset(rowKeys, colKeys, data);           
}   

}

運行效果圖：