Jsp Jfreechart：是否可以更改条形图的颜色？_Jsp_Jfreechart

Jsp Jfreechart：是否可以更改条形图的颜色？

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Jsp Jfreechart：是否可以更改条形图的颜色？,jsp,jfreechart,Jsp,Jfreechart,是否可以更改条形图的颜色我编写了一个简单的计数程序我还想实现一件事：如果计数数大于200，则使用蓝色绘制条。如果没有，请使用黄色来执行此操作目前，所有条颜色均为红色那么，我想问一下，有没有可能改变酒吧的颜色如果是的话，有人能给我一些实现的指导吗提前谢谢附件是我的编码： <%@page contentType="text/html"%> <%@page import="java.io.*" %> <%@page import="java.sql.*" %

是否可以更改条形图的颜色

我编写了一个简单的计数程序

我还想实现一件事：如果计数数大于200，则使用蓝色绘制条。如果没有，请使用黄色来执行此操作

目前，所有条颜色均为红色

那么，我想问一下，有没有可能改变酒吧的颜色

如果是的话，有人能给我一些实现的指导吗

提前谢谢

附件是我的编码：

<%@page contentType="text/html"%>
<%@page import="java.io.*" %>
<%@page import="java.sql.*" %>
<%@page import="org.jfree.data.category.*" %>
<%@page import="org.jfree.chart.*" %>
<%@page import="org.jfree.chart.plot.*" %>

<html>
<body>

<%
       DefaultCategoryDataset dataset = new DefaultCategoryDataset();
       try
        {

            Class.forName("com.mysql.jdbc.Driver");
            java.sql.Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/delivery","root","root");
            Statement sta = con.createStatement();
            ResultSet res = sta.executeQuery("SELECT inventory, subject from statistics");
            int count;
            String subject;

            while (res.next())
            {
                count = res.getInt("inventory");
                subject = res.getString("subject");
                dataset.addValue(count,"enrollment count statistics", subject);  
            }
        }
        catch (Exception e) { 
            System.err.println(e.getMessage());
        }   

        JFreeChart bar = ChartFactory.createBarChart("Enrollment Chart", "subject","Count",dataset, PlotOrientation.HORIZONTAL,true, false, false);   
        //BarRenderer renderer = (BarRenderer) bar.getCategoryPlot().getRenderer();

        String fileName = "/bar.png";
        String file = application.getRealPath("/") + fileName;

        try
        {
            FileOutputStream fileOut = new FileOutputStream(file);
            ChartUtilities.writeChartAsPNG(fileOut, bar, 300, 300);
        }
        catch (IOException e)
        {
             out.print(e);
        }


%>
<img src="/delivery/bar.png" alt="subject Bar Chart" />
</body>
</html>

获取一个句柄，并在其上调用setSeriesPaint（int系列，java.awt.Paint）。

魔法在于

例如：

您试图做的是：

class CustomRenderer extends BarRenderer
{

   public CustomRenderer()
   {
   }

   public Paint getItemPaint(final int row, final int column)
   {
      // returns color depending on y coordinate.
      return (row > 200) ? Color.blue : Color.yellow ;
   }
}

然后在调用ChartFactory.createBarChart之后，您可以

final CategoryPlot plot = chart.getCategoryPlot();
CategoryItemRenderer renderer = new CustomRenderer();
plot.setRenderer(renderer);

看看这个链接

 /**
 * A custom renderer that returns a different color for each item in a single series.
 */
class CustomRenderer extends BarRenderer {

    /** The colors. */
    private Paint[] colors;

    /**
     * Creates a new renderer.
     *
     * @param colors  the colors.
     */
    public CustomRenderer(final Paint[] colors) {
        this.colors = colors;
    }

    /**
     * Returns the paint for an item.  Overrides the default behaviour inherited from
     * AbstractSeriesRenderer.
     *
     * @param row  the series.
     * @param column  the category.
     *
     * @return The item color.
     */
    public Paint getItemPaint(final int row, final int column) {
        return this.colors[column % this.colors.length];
    }
}

此方法不能用于设置系列中条形图的颜色，这是OP想要完成的。改用

 /**
 * A custom renderer that returns a different color for each item in a single series.
 */
class CustomRenderer extends BarRenderer {

    /** The colors. */
    private Paint[] colors;

    /**
     * Creates a new renderer.
     *
     * @param colors  the colors.
     */
    public CustomRenderer(final Paint[] colors) {
        this.colors = colors;
    }

    /**
     * Returns the paint for an item.  Overrides the default behaviour inherited from
     * AbstractSeriesRenderer.
     *
     * @param row  the series.
     * @param column  the category.
     *
     * @return The item color.
     */
    public Paint getItemPaint(final int row, final int column) {
        return this.colors[column % this.colors.length];
    }
}