package charts;

import java.awt.Font;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.http.HttpSession;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartRenderingInfo;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.entity.StandardEntityCollection;
import org.jfree.chart.labels.StandardPieSectionLabelGenerator;
import org.jfree.chart.plot.RingPlot;
import org.jfree.chart.servlet.ServletUtilities;
import org.jfree.chart.title.TextTitle;
import org.jfree.data.general.DefaultPieDataset;
import org.jfree.data.general.PieDataset;
public class PieChart
{
	 /**
     * 构造报表的结果集
     * @return
     */
    private static PieDataset createDataset() {
        DefaultPieDataset dataset = new DefaultPieDataset();
        dataset.setValue("居民", new Double(0.25));
        dataset.setValue("农业", new Double(0.14));
        dataset.setValue("建筑业", new Double(0.03));
        dataset.setValue("商业", new Double(0.15));
        dataset.setValue("工业", new Double(0.30));
        dataset.setValue("其他", new Double(0.13));
        return dataset;        
    }
    /**
     * 根据结果集构造JFreechart报表对象
     * @param xyDataSet
     * @return
     */
    private static JFreeChart createChart(PieDataset pieDataSet)
    {
        JFreeChart jfreechart = ChartFactory.createRingChart(
                "短期人民币贷款结构",       //报表标题 
                pieDataSet,              //数据集 
                false,                   //是否显示图例
                true,                    //是否有工具条提示
                false                    //是否有链接
                );   
        jfreechart.addSubtitle(new TextTitle("------《2008年银行业行业报告》", new Font(
                "Dialog", Font.ITALIC, 10)));
        RingPlot plot = (RingPlot) jfreechart.getPlot();
        plot.setLabelFont(new Font("SansSerif", Font.PLAIN, 12));
        plot.setLabelGenerator(new StandardPieSectionLabelGenerator(
        "{0} ({2} )"));
        plot.setSectionDepth(0.50);
        plot.setCircular(false);
        plot.setLabelGap(0.02);
        return jfreechart;
    }
    /**
     * 生成饼图的图片，返回图片文件的名称
     * 
     * @param session
     * @param pw
     * @return
     */
    public static String generatePieChart(HttpSession session, PrintWriter pw)
    {
        String filename = null;
        PieDataset pieDataset = createDataset();
        JFreeChart chart = createChart(pieDataset);
        ChartRenderingInfo info = new ChartRenderingInfo(
                new StandardEntityCollection());
        try
        {
            filename = ServletUtilities.saveChartAsPNG(chart, 500, 300, info,
                    session);
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        try
        {
            ChartUtilities.writeImageMap(pw, filename, info, false);
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        pw.flush();
        return filename;
    }
}