JFreeChart饼图绘制手顺
1 将jfreechart配置到web容器中。即在web.xml中配置
??? <servlet>
?????? <servlet-name>DisplayChart</servlet-name>
???????<servlet-class>
??????? ?org.jfree.chart.servlet.DisplayChart
?????? </servlet-class>
??? </servlet>
??? <servlet-mapping>
???????<servlet-name>DisplayChart</servlet-name>
?????? <url-pattern>/servlet/DisplayChart</url-pattern>
??? </servlet-mapping>
2 绘图，并保存至内存
?? ?//方法各块的分布及显示信息,需要将饼图切成几块就执行几次
??? DefaultPieDataset.setValue(string message,double value)
??? //穿件3D饼图对象
????JFreeChart chart = ChartFactory.createPieChart3D(String title, DefaultPieDataset dataset,boolean legend,boolean tooltips, boolean urls);
??? //获取饼图中块对象，通过该快对象可以对饼图中的块进行描述
??? PiePlot3D plot = (PiePlot3D) chart.getPlot();
??? //生成图小标准渲染信息
??? ChartRenderingInfo info = new ChartRenderingInfo(new StandardEntityCollection());?
??? //根据以后信息绘制图片，并保存到Session中
??? String fileName = ServletUtilities.saveChartAsPNG( JFreeChart chart,int width,int height,ChartRenderingInfo info,HttpSession session);
3 页面获取图片
???? filePath为request.getContextPath()?+ "/servlet/DisplayChart?filename=" + fileName
???? <img id="pic" src="${filePath?default('')}" border="0" usemap="#${fileName?default('')}" />
