java类中生成jfreechart,返回图表的url地址

web.xml中设置：

<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>/DisplayChart</url-pattern>
</servlet-mapping>

java类中方法：

public String getChart(String series[],double score[][],String type[],String name){
final int num=8;
DefaultCategoryDataset defaultcategorydataset = new DefaultCategoryDataset();
for(int i=0;i<type.length;i++){
type[i]=type[i].substring(0, (type[i].length()<num)?type[i].length():num);
}

for(int j=0;j<series.length;j++){
int i=0;
for( i=0;i<type.length;i++){
defaultcategorydataset.addValue(score[j][i], series[j], type[i]);
}
}

JFreeChart jfreechart = ChartFactory.createLineChart(name,null,null,defaultcategorydataset,PlotOrientation.VERTICAL,true,true,false);

jfreechart.getLegend().setPosition(RectangleEdge.RIGHT);

jfreechart.setBackgroundPaint(Color.white);

CategoryPlot categoryplot = (CategoryPlot)jfreechart.getPlot();
categoryplot.setNoDataMessage("无数据可供显示！");
categoryplot.setBackgroundPaint(Color.white);
categoryplot.setDomainGridlinesVisible(true);
categoryplot.setRangeGridlinesVisible(true);
categoryplot.setRangeGridlinePaint(Color.gray);
categoryplot.setDomainGridlinePaint(Color.gray);
categoryplot.setBackgroundAlpha(0.8f);
Font font1 = new Font("黑体",Font.BOLD, 14);
jfreechart.getTitle().setFont(font1);

Font font3 = new Font("隶书",Font.BOLD, 12);
jfreechart.getLegend().setItemFont(font3);

CategoryAxis categoryaxis = categoryplot.getDomainAxis();
// categoryaxis.setCategoryLabelPositions(CategoryLabelPositions.UP_45);
categoryaxis.setMaximumCategoryLabelLines(10);//行数，根据需要自己设
categoryaxis.setMaximumCategoryLabelWidthRatio(0.5f);//每行宽度，这里设一个汉字宽

NumberAxis numberaxis = (NumberAxis)categoryplot.getRangeAxis();
numberaxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
numberaxis.setAutoRangeIncludesZero(true);
numberaxis.setRangeWithMargins(0, 3);

numberaxis.setUpperMargin(0.8);////设置最高的一个 Item 与图片顶端的距离
numberaxis.setUpperBound(3.5);//纵坐标最大值

categoryaxis.setTickLabelFont(new Font("宋体", Font.BOLD, 12));
numberaxis.setTickLabelFont(new Font("隶书", Font.BOLD, 12));
Font font2 = new Font("SimSun", Font.BOLD, 16);
categoryaxis.setLabelFont(font2);
numberaxis.setLabelFont(font2);
categoryplot.setAxisOffset(new RectangleInsets(0D, 0D,0D, 10D));//设置曲线图与xy轴的距离
LineAndShapeRenderer lineandshaperenderer = (LineAndShapeRenderer)categoryplot.getRenderer();
lineandshaperenderer.setShapesVisible(true); //数据点可见

lineandshaperenderer.setSeriesStroke(0, new BasicStroke(2.0F, 1, 1, 1.0F, new float[] {
10F, 6F
}, 0.0F)); //定义series点之间的连线 ，这里是虚线，默认是直线
lineandshaperenderer.setSeriesStroke(1, new BasicStroke(2.0F, 1, 1, 1.0F, new float[] {
6F, 6F
}, 0.0F));

lineandshaperenderer.setBaseItemLabelsVisible(true);
lineandshaperenderer.setBaseItemLabelGenerator(new StandardCategoryItemLabelGenerator());

ChartRenderingInfo info=new ChartRenderingInfo(new StandardEntityCollection());
String fileName = null;
try
{
fileName = ServletUtilities.saveChartAsPNG(jfreechart, 700,300, info, null);//生成图片
}
catch (IOException e)
{
e.printStackTrace();
}

String graphURL = "/projectname/DisplayChart?filename=" + fileName; //projectname为对应项目的路径path,一般就是项目名称

//jsp中这样使用： String graphURL = request.getContextPath() + "/DisplayChart?filename=" + filename;
return graphURL;//返回生成图片的地址
}

调用上述方法得到生成的chart的url：

　　 getChart(stus,score_field,type,"总分图");