修改jfreechart-1.0.2柱状图的间距

修改org\jfree\chart\renderer\category中的BarRenderer.java文件中的double used = space * (1.0 - domainAxis.getLowerMargin()
                                     - domainAxis.getUpperMargin()
                                     - categoryMargin - currentItemMargin); 

为double used = space * (1.3 - domainAxis.getLowerMargin()
                                     - domainAxis.getUpperMargin()
                                     - categoryMargin - currentItemMargin);

然后替换相应的包中的类文件，就可以改变BarChart3D柱状图间距。