JFreeChart—输出时序图

时序图（Time Series Chart）是按照时间轴显示的图形。通常可以按照年、月、日等时间周来显示。

实现代码：

TimeChartServlet.java

package com.lmb.jfreechart;

import java.awt.BasicStroke;
import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYLineAndShapeRenderer;
import org.jfree.data.general.SeriesException;
import org.jfree.data.time.Day;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.xy.XYDataset;

public class TimeChartServlet extends HttpServlet {

    private static final long serialVersionUID = -2380167170122284327L;

    public TimeChartServlet() {
        super();
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        // 设置返回类型为图片
        response.setContentType("image/png");
        // 获取数据集对象
        XYDataset dataset = createDataset();
        // 创建图形对象
        JFreeChart jfreechart = ChartFactory.createTimeSeriesChart("时序图","POLO历史价格", "价格", dataset, false, false, false);
        XYPlot xyplot = (XYPlot) jfreechart.getPlot();
        //获得折线显示对象
        XYLineAndShapeRenderer xylineandshaperenderer = new XYLineAndShapeRenderer();
        //设置不显示折线
        xylineandshaperenderer.setBaseShapesVisible(false);
        //设置折线的粗细
        xylineandshaperenderer.setSeriesStroke(0, new BasicStroke(0.5F, 1, 1, 5F, new float[] { 5F, 10F }, 0.0F));
        xyplot.setRenderer(xylineandshaperenderer);

        // 将图表已数据流的方式返回给客户端
        ChartUtilities.writeChartAsPNG(response.getOutputStream(), jfreechart,
                500, 270);
    }

    /** * 返回数据集 * * @return */
    private static XYDataset createDataset() {
        //创建时序对象
        TimeSeries timeseries = new TimeSeries("JAVA");
        //初始化日期为1990年1月1日
        Day day = new Day(1, 1, 1990);
        double d = 100000D;
        //添加1000条数据
        for (int i = 0; i < 4000; i++)
            try {
                //随机取出100附近数
                d = (d + Math.random()) - 0.5D;
                //添加到时序对象
                timeseries.add(day, new Double(d));
                //之后的一天
                day = (Day) day.next();
            } catch (SeriesException seriesexception) {

            }
        //返回XYDataset数据集
        return new TimeSeriesCollection(timeseries);
    }
}

web.xml略。。。

总结：

1、利用XYDataset数据集绘制时序图，时序图的数据集可以通过TimeSeries对象设置；

2、对应创建时序图的方法是createTimeSeriesChart()；

3、利用XYLineAndShapeRenderer对象设置绘制线条的显示方式。