【JFreeChart】JFreeChart—输出折线图

迈不过友情╰ 2022-08-01 11:09 141阅读 0赞

# 实现代码： #

**LineChartServlet.java**

package com.lmb.jfreechart;
    
    import java.awt.BasicStroke;
    import java.awt.Color;
    import java.awt.Font;
    import java.io.IOException;
    import java.util.Date;
    
    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.CategoryPlot;
    import org.jfree.chart.plot.PlotOrientation;
    import org.jfree.chart.renderer.category.LineAndShapeRenderer;
    import org.jfree.chart.title.TextTitle;
    import org.jfree.data.category.CategoryDataset;
    import org.jfree.data.category.DefaultCategoryDataset;
    import org.jfree.ui.HorizontalAlignment;
    import org.jfree.ui.RectangleEdge;
    
    public class LineChartServlet extends HttpServlet {
        
    
        private static final long serialVersionUID = 1585397081043433662L;
    
        public LineChartServlet() {
            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
            CategoryDataset dataset = createDataset();
            // 创建图形对象
            JFreeChart jfreechart = ChartFactory.createLineChart("08年图书销售量",
                    null, "销售量", dataset, PlotOrientation.VERTICAL, false, true,
                    false);
            // 设置图表的子标题
            jfreechart.addSubtitle(new TextTitle("按月份"));
            // 创建一个标题
            TextTitle texttitle = new TextTitle("日期: " + new Date());
            // 设置标题字体
            texttitle.setFont(new Font("黑体", 0, 10));
            // 设置标题向下对齐
            texttitle.setPosition(RectangleEdge.BOTTOM);
            // 设置标题向右对齐
            texttitle.setHorizontalAlignment(HorizontalAlignment.RIGHT);
            // 添加图表的子标题
            jfreechart.addSubtitle(texttitle);
            // 设置图表的背景色为白色
            jfreechart.setBackgroundPaint(Color.white);
            // 获得图表区域对象
            CategoryPlot categoryplot = (CategoryPlot) jfreechart.getPlot();
            categoryplot.setBackgroundPaint(Color.lightGray);
            categoryplot.setRangeGridlinesVisible(false);
            // 获显示线条对象
            LineAndShapeRenderer lineandshaperenderer = (LineAndShapeRenderer) categoryplot
                    .getRenderer();
            lineandshaperenderer.setBaseShapesVisible(true);
            lineandshaperenderer.setDrawOutlines(true);
            lineandshaperenderer.setUseFillPaint(true);
            lineandshaperenderer.setBaseFillPaint(Color.white);
            // 设置折线加粗
            lineandshaperenderer.setSeriesStroke(0, new BasicStroke(3F));
            lineandshaperenderer.setSeriesOutlineStroke(0, new BasicStroke(2.0F));
            // 设置折线拐点
            lineandshaperenderer.setSeriesShape(0,
                    new java.awt.geom.Ellipse2D.Double(-5D, -5D, 10D, 10D));
    
            // 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 CategoryDataset createDataset() {
            DefaultCategoryDataset defaultdataset = new DefaultCategoryDataset();
            for (int i = 1; i <= 12; i++) {
                defaultdataset.addValue(DataUtils.getRandomData(), "JAVA", i + "月");
                defaultdataset.addValue(DataUtils.getRandomData(), "PHP", i + "月");
    
            }
            return defaultdataset;
        }
    
    }

web.xml略。。。

# 总结： #

1、利用CategoryGataSet数据集绘制折线图；

2、对应创建折线图的方法是createLineChart()；

3、通过TextTitle对象设置图表的子标题；

4、利用LineAndShapeRenderer线条对象，设置折线的显示方式。