【JFreeChart】JFreeChart—输出时序图

r囧r小猫 2022-08-01 11:09 196阅读 0赞

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。