JFreeChart的很多画图工作都是委派给Plot的，可以通过如下方式获取Plot的引用

获取Plot

 Plot plot= chart.getPlot();

如果知道是哪个子类也可以转换为对应的子类

PiePlot plot1= (PiePlot)chart.getPlot();

设置字体

        Font fontLabel=new Font("宋体",Font.PLAIN,24);
        //设置字体
        plot1.setLabelFont(fontLabel);

设置说明（Legend）的内容格式

/**
 * A standard item label generator for plots that use data from a
 * {@link PieDataset}.
 * <p>
 * For the label format, use {0} where the pie section key should be inserted,
 * {1} for the absolute section value and {2} for the percent amount of the pie
 * section, e.g. {@code "{0} = {1} ({2})"} will display as
 * {@code apple = 120 (5%)}.
 */
       plot1.setLegendLabelGenerator(new StandardPieSectionLabelGenerator("{0} = {1} ({2})"));

设置标签生成内容格式

 plot1.setLabelGenerator(new StandardPieSectionLabelGenerator("{0} = {1} ({2})"));

设置背景颜色

plot1.setBackgroundPaint(Color.CYAN);

pie2.png