使用JFreeChart生成XY轴折线图

第一步：
Java代码 

<span style="font-size: medium;">//生成折线图的处理类(其他DOMAIN类代码省略)     
public class CreateJFreeChartXYLine {  
    // 保存为文件  
    public static void saveAsFile(JFreeChart chart, String outputPath,  
            int weight, int height) {  
        FileOutputStream out = null;  
        try {  
            File outFile = new File(outputPath);  
            if (!outFile.getParentFile().exists()) {  
                outFile.getParentFile().mkdirs();  
            }  
            out = new FileOutputStream(outputPath);  
  
            // 保存为PNG  
            ChartUtilities.writeChartAsPNG(out, chart,500, 400);  
            // 保存为JPEG  
            // ChartUtilities.writeChartAsJPEG(out, chart, 500, 400);  
            out.flush();  
        } catch (FileNotFoundException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        } finally {  
            if (out != null) {  
                try {  
                    out.close();  
                } catch (IOException e) {  
                    // do nothing  
                }  
            }  
        }  
    }  
  
    // 根据XYDataset创建JFreeChart对象  
    public static JFreeChart createChart(XYDataset dataset) {  
        // 创建JFreeChart对象：ChartFactory.createXYLineChart  
        JFreeChart jfreechart = ChartFactory.createTimeSeriesChart("折线模型图",  
                "年份", "数量", dataset, false, true, false);  
        jfreechart.getTitle().setFont(new Font("宋体", Font.BOLD, 12));  
        // 使用CategoryPlot设置各种参数。以下设置可以省略。  
        XYPlot plot = (XYPlot) jfreechart.getPlot();  
        // 背景色 透明度  
        plot.setBackgroundAlpha(0.5f);  
        // 前景色 透明度  
        plot.setForegroundAlpha(0.5f);  
        // 其它设置可以参考XYPlot类  
        ValueAxis categoryaxis = plot.getDomainAxis(); // 横轴上的  
        categoryaxis.setPositiveArrowVisible(true);// 增加横轴的箭头  
        plot.getRangeAxis().setPositiveArrowVisible(true);// 增加纵轴的箭头  
        categoryaxis.setTickLabelFont(new Font("宋体", 10, 12));// 设定字体、类型、字号  
        DateAxis axis = (DateAxis) plot.getDomainAxis();  
        axis.setDateFormatOverride(new SimpleDateFormat("MM月"));  
        NumberAxis numberaxis = new NumberAxis("统计报表");//侧面显示的标题  
        numberaxis.setAutoRangeIncludesZero(false);  
        plot.setRangeAxis(1, numberaxis);  
        plot.setDataset(1, dataset);  
        plot.mapDatasetToRangeAxis(1, 1);  
        XYItemRenderer xyitemrenderer = plot.getRenderer();  
        StandardXYItemRenderer standardxyitemrenderer1 = new StandardXYItemRenderer();  
        standardxyitemrenderer1.setSeriesPaint(0, Color.black);  
        standardxyitemrenderer1.setSeriesPaint(0, Color.black);  
        standardxyitemrenderer1.setPlotLines(true);  
        LegendTitle legendtitle = new LegendTitle(xyitemrenderer);  
        LegendTitle legendtitle1 = new LegendTitle(standardxyitemrenderer1);  
        BlockContainer blockcontainer = new BlockContainer(  
                new BorderArrangement());  
        blockcontainer.add(legendtitle, RectangleEdge.LEFT);  
        blockcontainer.add(legendtitle1, RectangleEdge.RIGHT);//这两行代码可以控制位置  
        blockcontainer.add(new EmptyBlock(2000D, 0.0D));  
        CompositeTitle compositetitle = new CompositeTitle(blockcontainer);  
        compositetitle.setPosition(RectangleEdge.BOTTOM);//放置图形代表区域位置的代码  
        jfreechart.addSubtitle(compositetitle);  
        Font font2 = new Font("宋体", 10, 16); // 设定字体、类型、字号  
        plot.getDomainAxis().setLabelFont(font2);// 相当于横轴或理解为X轴  
        plot.getRangeAxis().setLabelFont(font2);// 相当于竖轴理解为Y轴  
        return jfreechart;  
    }  
  
    /** 
     * 创建XYDataset对象 
     *  
     */  
    public static XYDataset createXYDataset() {  
        MyChartService ms = new MyChartService();  
        // XYSeriesCollection xySeriesCollection = new XYSeriesCollection();  
        TimeSeriesCollection timeseriescollection = new TimeSeriesCollection();  
        List<String> names = ms.listall();  
        for (String name : names) {  
            System.out.println(name);  
            TimeSeries timeseries = new TimeSeries(name);  
            List<MyChart> mcs = ms.FindByName(name);  
            for (MyChart mc : mcs) {  
                Calendar cc = Calendar.getInstance();  
                System.out.println(mc.getScore());  
                cc.setTime(mc.getDate());  
                timeseries.add(new Month(cc.get(Calendar.MONTH), cc  
                        .get(Calendar.YEAR)), mc.getScore());  
                // xyseries.add(mc.getDate(),mc.getScore());  
  
            }  
            // xySeriesCollection.addSeries(timeseries);  
            timeseriescollection.addSeries(timeseries);  
  
        }  
  
        return timeseriescollection;  
    }  
</span> 

第二步：如果配合Struts1使用的话
Java代码 

<span style="font-size: medium;">request.setCharacterEncoding("gbk");   
response.setContentType("image/jpeg;charset=gbk");   
MyChartService ms=new MyChartService();   
//步骤1：创建XYDataset对象（准备数据）     
        XYDataset dataset =CreateJFreeChartXYLine.createXYDataset();     
        //步骤2：根据Dataset 生成JFreeChart对象，以及做相应的设置     
        JFreeChart freeChart =CreateJFreeChartXYLine.createChart(dataset);     
        //步骤3：将JFreeChart对象输出到文件，Servlet输出流等     
        String url= "c:\\jfreechart\\lineXY.png";   
        CreateJFreeChartXYLine.saveAsFile(freeChart,url, 900, 700);    
        request.setAttribute("url", url);   
        request.setAttribute("lists", ms.listall());   
return mapping.findForward("list");   
</span>  

直接将路径发到JSP页面，从而达到显示图片效果