JFreeChart通过点击图表的XY系列坐标。

Question

我试图在用户点击JFreeChart提供的XY系列图表中的一个点时，分别获得X和Y坐标。我也是在一个使用Java编程语言的servlet中做的。List 是我从一个模型包中制作的对象，这个模型包的类叫做 Home和 Away. 欢迎询问更多关于servlet的信息，因为我提供的是下面的代码。

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Object saved in application scopes two list one fore Home and Away   

        List<Home> forumi = (List<Home>) getServletContext().getAttribute(
                "home" );

        List<Away> forumi2 = (List<Away>) getServletContext().getAttribute(
                "away" );

        OutputStream out = response.getOutputStream(); 

        try {
            //creating an XY dataset
             XYSeriesCollection dataset = new XYSeriesCollection();
                XYSeries series1 = new XYSeries("Home");
                XYSeries series2 = new XYSeries("Away");

        //inputing data to chart
        int counter = 1;
        for(int i=0; i < forumi.size(); i++) {
            series1.add(counter, forumi.get(i).getScores());
            ++counter;
        }

        int counter2 = 1;
        for(int i=0; i < forumi2.size(); i++) {
            series2.add(counter2, forumi2.get(i).getScores());
            ++counter2;
        }

        dataset.addSeries(series1);
        dataset.addSeries(series2);
        /* create chart */
        String chartTitle = "2019-2020";
        String xAxisLabel = "game";
        String yAxisLabel = "Scores";

        JFreeChart chart = ChartFactory.createXYLineChart(chartTitle,
                xAxisLabel, yAxisLabel, dataset);

        //Customize chart
         XYPlot plot = chart.getXYPlot();
         XYLineAndShapeRenderer renderer = new XYLineAndShapeRenderer();
        // sets thickness for series (using strokes)
         renderer.setSeriesPaint(0, Color.RED);
         renderer.setSeriesPaint(1, Color.BLUE);
        // sets paint color for each series
         renderer.setSeriesStroke(0, new BasicStroke(2.0f));
         renderer.setSeriesStroke(1, new BasicStroke(2.0f));
         //renderer.setSeriesStroke(1, new BasicStroke(3.0f));

         plot.setRenderer((XYItemRenderer) renderer);
         chartPanel = new ChartPanel(chart);   
        //System.out.print(plot.getRangeCrosshairValue()); 

        chart.getPlot().setBackgroundPaint(Color.WHITE);
        /* Set the HTTP Response Type */
        response.setContentType("image/png");

        /* Writes a chart to an output stream in PNG format */
        ChartUtilities.writeChartAsPNG(out, chart, 1704, 300);


        } catch (Exception e) {
        System.err.println(e.toString()); /* Throw exceptions to log files */
        } finally {
        out.close();/* Close the output stream */
        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    } ```

Answer 1

如图所示 例子，您可以创建一个 HTML图像地图 对应于图表中的实体，以便在servlet上下文中使用。

设置 tooltips 到 true 在你选择的 ChartFactory 增加了 StandardXYToolTipGenerator 鼠标移动事件时将会显示一个工具提示；鼠标在实体上移动时将会显示一个工具提示。scatter.html 来查看效果；你可以自定义生成器，如图所示。此处 和 此处.

设置 urls 到 true 在你选择的 ChartFactory 增加了 StandardXYURLGenerator 它将在鼠标点击事件时打开生成的URL；点击一个实体在 scatter.html 与自定义生成器一起看效果。

chart.getXYPlot().getRenderer().setURLGenerator(new StandardXYURLGenerator(){
    @Override
    public String generateURL(XYDataset dataset, int series, int item) {
        return "http://example.com";
    }
});

你的实际生成器可以为特定值的 dataset, series 和 item.