小編給大家分享一下如何使用JFreeChart實現折線圖，相信大部分人都還不怎么了解，因此分享這篇文章給大家參考一下，希望大家閱讀完這篇文章后大有收獲，下面讓我們一起去了解一下吧！

折線圖，大可分為兩種，

（1）X軸值類型為String的。

2)常用的是X軸值是日期的，并且，有時需要滿足這樣的需求：

1、時間要連續。

2、時間可以設置固定的跨度，比如，2009-02-01，2009-02-04，2009-02-07……

3、由于時間跨度較大，想要做到不同精度的圖表，如時間為10天時，以日（yyyy-MM-dd）格式為精度，時間跨度為2個月時，以周（如2009年第3周）為精度，跨度為6個月時，以月（2009年8月）為精度。

下面，針對比較復雜的（2）來講解：

1、取到業務邏輯需要的數據：(具體過程就不啰嗦了，就是查詢數據庫，得到想要的字段的值，加載到List里面) 返回List<PressureBean>

PressureBean的包含的屬性：

intuserId;StringbpDate;StringbpTime;intsyspress;//收縮壓(mmHg)intdiapress;//舒張壓(mmHg)

2、加載數據集

publicstaticTimeSeriesCollectioncreateTimeSeries(List<PressureBean>list,intdayOrweekOrmonth,Loglog,Stringshou,Stringshu){TimeSeriesCollectiontimesers=newTimeSeriesCollection();intmon=1;intday=1;intye=2000;intweek=1;//按天顯示if(dayOrweekOrmonth==0){TimeSeriestimeseries=newTimeSeries(shou,org.jfree.data.time.Day.class);TimeSeriestimeseries1=newTimeSeries("c1",org.jfree.data.time.Day.class);TimeSeriestimeseriedia=newTimeSeries(shu,org.jfree.data.time.Day.class);TimeSeriestimeseriedia1=newTimeSeries("d1",org.jfree.data.time.Day.class);Iterator<PressureBean>it=list.iterator();while(it.hasNext()){PressureBeanpres=it.next();Stringdate=pres.getBpDate();ye=Integer.parseInt(date.substring(0,4));mon=Integer.parseInt(date.substring(5,7));day=Integer.parseInt(date.substring(8,date.length()));Daydays=newDay(day,mon,ye);doublesys=pres.getSyspress();doubledia=pres.getDiapress();if(sys!=-1&&sys>0){timeseries.add(days,sys);}else{timeseries1.add(days,null);}if(sys!=-1&&sys>0){timeseriedia.add(days,dia);}else{timeseriedia1.add(days,null);}}timesers.addSeries(timeseries);timesers.addSeries(timeseriedia);timesers.addSeries(timeseries1);timesers.addSeries(timeseriedia1);}elseif(dayOrweekOrmonth==1){//按周顯示TimeSeriestimeseries=newTimeSeries(shou,org.jfree.data.time.Week.class);TimeSeriestimeseries1=newTimeSeries("c1",org.jfree.data.time.Week.class);TimeSeriestimeseriedia=newTimeSeries(shu,org.jfree.data.time.Week.class);TimeSeriestimeseriedia1=newTimeSeries("d1",org.jfree.data.time.Week.class);Iterator<PressureBean>it=list.iterator();while(it.hasNext()){PressureBeanpres=it.next();Stringdate=pres.getBpDate();String[]spls=date.split("-");if(spls.length==2){ye=Integer.parseInt(spls[0]);mon=Integer.parseInt(spls[1]);}else{log.error("thedateofweeksiswrong");}Weekdays=newWeek(mon,ye);doublesys=pres.getSyspress();doubledia=pres.getDiapress();if(sys!=-1&&sys>0){timeseries.add(days,sys);}else{timeseries1.add(days,null);}if(sys!=-1&&sys>0){timeseriedia.add(days,dia);}else{timeseriedia1.add(days,null);}}timesers.addSeries(timeseries);timesers.addSeries(timeseriedia);timesers.addSeries(timeseries1);timesers.addSeries(timeseriedia1);}else{//按月顯示TimeSeriestimeseries=newTimeSeries(shou,org.jfree.data.time.Month.class);TimeSeriestimeseries1=newTimeSeries("c1",org.jfree.data.time.Month.class);TimeSeriestimeseriedia=newTimeSeries(shu,org.jfree.data.time.Month.class);TimeSeriestimeseriedia1=newTimeSeries("s",org.jfree.data.time.Month.class);Iterator<PressureBean>it=list.iterator();while(it.hasNext()){PressureBeanpres=it.next();Stringdate=pres.getBpDate();String[]spls=date.split("-");if(spls.length==2){ye=Integer.parseInt(spls[0]);mon=Integer.parseInt(spls[1]);}else{log.error("thedateofweeksiswrong");}Monthdays=newMonth(mon,ye);doublesys=pres.getSyspress();doubledia=pres.getDiapress();if(sys!=-1&&sys>0){timeseries.add(days,sys);}else{timeseries1.add(days,null);}if(sys!=-1&&sys>0){timeseriedia.add(days,dia);}else{timeseriedia1.add(days,null);}}timesers.addSeries(timeseries);timesers.addSeries(timeseriedia);timesers.addSeries(timeseries1);timesers.addSeries(timeseriedia1);}returntimesers;}

3、畫折線圖，兩個數據集，收縮壓和舒張壓，并且，這兩條曲線還各自包含一個區域范圍，并不單單是一條基準線，而是一個基準范圍。

privatestaticJFreeChartcreateChartPress(XYDatasetxydataset,intweekOrmonth,Stringtitle,Stringy,Stringindex,Stringweek,Stringyear,intsearchby,Stringmonth,Stringnodatamess,Listlist,Loglog,Stringbp_shou,Stringbp_shuzhang){//有可能用戶在后面的版本中故意輸入不正常數值，但是為了保證圖片畫圖的完整，這里先計算//用戶血壓值的***值。doublemaxpress=0;doubleaddmax=50;doublemin=40;if(list!=null&&list.size()>0){Iterator<PressureBean>it=list.iterator();while(it.hasNext()){PressureBeanpres=it.next();doublesys=pres.getSyspress();doubledia=pres.getDiapress();if(maxpress<sys){maxpress=sys;}if(maxpress<dia)maxpress=dia;if(min>sys){min=sys;}if(min>dia)min=dia;}maxpress+=addmax;min-=10;log.info("highpressvalueis="+maxpress);}if(xydataset!=null){intcounts=xydataset.getItemCount(0);if(counts==0){xydataset=null;}}JFreeChartjfreechart=ChartFactory.createTimeSeriesChart(title,"",y,xydataset,true,true,false);jfreechart.setBackgroundPaint(Color.white);//設置標題的顏色TextTitletext=newTextTitle(title);text.setPaint(newColor(102,102,102));jfreechart.setTitle(text);XYPlotxyplot=jfreechart.getXYPlot();xyplot.setBackgroundPaint(newColor(255,253,246));xyplot.setOutlineStroke(newBasicStroke(1.5f));//邊框粗細ValueAxisvaxis=xyplot.getDomainAxis();vaxis.setAxisLineStroke(newBasicStroke(1.5f));//坐標軸粗細vaxis.setAxisLinePaint(newColor(215,215,215));//坐標軸顏色xyplot.setOutlineStroke(newBasicStroke(1.5f));//邊框粗細vaxis.setLabelPaint(newColor(10,10,10));//坐標軸標題顏色vaxis.setTickLabelPaint(newColor(102,102,102));//坐標軸標尺值顏色vaxis.setLowerMargin(0.06d);//分類軸下（左）邊距vaxis.setUpperMargin(0.14d);//分類軸下（右）邊距,防止***邊的一個數據靠近了坐標軸。//X軸為日期格式，這里是專門的處理日期的類，SimpleDateFormatformat=newSimpleDateFormat("yyyy-MM-dd");DateAxisdateaxis=(DateAxis)xyplot.getDomainAxis();if(weekOrmonth==0){//以天為刻度，時間格式為yyyy-MM-dd,如2008-02-06dateaxis.setTickUnit(newDateTickUnit(DateTickUnit.DAY,1,format));}elseif(weekOrmonth==1){//以周為刻度，時間顯示為2009年第4周（（這里是SimpleDateFormat的用法，//這里為了作繁體版，英文版和簡體版，用了國際化處理，將這些可變的資源在文字資源里面，注意一下，這里的y，M、w是SimpleDateFormat的關鍵字，//如英文表示09年第3周就是09W3，那么，這里的W需要用&lsquo;&rsquo;引起來）format=newSimpleDateFormat("yyyy"+year+index+"w"+week);dateaxis.setTickUnit(newDateTickUnit(DateTickUnit.DAY,7,format));}elseif(weekOrmonth==2){//以月為刻度，時間顯示為09-02（09年2月）format=newSimpleDateFormat("yy-MM");dateaxis.setTickUnit(newDateTickUnit(DateTickUnit.MONTH,1,format));}dateaxis.setVerticalTickLabels(false);//設為true表示橫坐標旋轉到垂直。if(searchby==6||searchby==3){dateaxis.setAutoTickUnitSelection(true);//由于橫軸標簽過多，這里設置為自動格式。dateaxis.setDateFormatOverride(format);}dateaxis.setTickMarkPosition(DateTickMarkPosition.START);ValueAxisvalueAxis=xyplot.getRangeAxis();valueAxis.setUpperBound(maxpress);valueAxis.setAutoRangeMinimumSize(1);valueAxis.setLowerBound(min);valueAxis.setAutoRange(false);valueAxis.setAxisLineStroke(newBasicStroke(1.5f));//坐標軸粗細valueAxis.setAxisLinePaint(newColor(215,215,215));//坐標軸顏色valueAxis.setLabelPaint(newColor(10,10,10));//坐標軸標題顏色valueAxis.setTickLabelPaint(newColor(102,102,102));//坐標軸標尺值顏色xyplot.setRangeGridlinesVisible(true);xyplot.setDomainGridlinesVisible(true);xyplot.setRangeGridlinePaint(Color.LIGHT_GRAY);xyplot.setDomainGridlinePaint(Color.LIGHT_GRAY);xyplot.setBackgroundPaint(newColor(255,253,246));xyplot.setNoDataMessage(nodatamess);//沒有數據時顯示的文字說明。xyplot.setNoDataMessageFont(newFont("",Font.BOLD,14));//字體的大小，粗體。xyplot.setNoDataMessagePaint(newColor(87,149,117));//字體顏色xyplot.setAxisOffset(newRectangleInsets(0d,0d,0d,5d));////addrangemarker(舒張壓的區域marker,范圍是從62到81)doublelowpress=62;doubleuperpress=81;IntervalMarkerintermarker=newIntervalMarker(lowpress,uperpress);intermarker.setPaint(Color.decode("#66FFCC"));//域顏色intermarker.setLabelFont(newFont("SansSerif",41,14));intermarker.setLabelPaint(Color.RED);intermarker.setLabel(bp_shuzhang);if(xydataset!=null){xyplot.addRangeMarker(intermarker,Layer.BACKGROUND);}//(收縮壓的區域marker，范圍是從102到120)doublelowpress1=102;doubleuperpress1=120;IntervalMarkerinter=newIntervalMarker(lowpress1,uperpress1);inter.setLabelOffsetType(LengthAdjustmentType.EXPAND);inter.setPaint(Color.decode("#66FFCC"));//域顏色inter.setLabelFont(newFont("SansSerif",41,14));inter.setLabelPaint(Color.RED);inter.setLabel(bp_shou);if(xydataset!=null){xyplot.addRangeMarker(inter,Layer.BACKGROUND);//加上Layer.BACKGROUND，將maker調到折線下面。}XYLineAndShapeRendererxylineandshaperenderer=(XYLineAndShapeRenderer)xyplot.getRenderer();//***條折線的顏色xylineandshaperenderer.setBaseItemLabelsVisible(true);xylineandshaperenderer.setSeriesFillPaint(0,newColor(127,128,0));xylineandshaperenderer.setSeriesPaint(0,newColor(127,128,0));xylineandshaperenderer.setSeriesShapesVisible(0,true);xylineandshaperenderer.setSeriesShapesVisible(1,true);//第二條折線的顏色xylineandshaperenderer.setSeriesFillPaint(1,newColor(254,103,0));xylineandshaperenderer.setSeriesPaint(1,newColor(254,103,0));xylineandshaperenderer.setSeriesShapesVisible(1,true);xylineandshaperenderer.setSeriesVisible(2,false);//xylineandshaperenderer.setSeriesVisible(3,false);//不顯示下面標題//折線的粗細調StandardXYToolTipGeneratorxytool=newStandardXYToolTipGenerator();xylineandshaperenderer.setToolTipGenerator(xytool);xylineandshaperenderer.setStroke(newBasicStroke(1.5f));//顯示節點的值xylineandshaperenderer.setBaseItemLabelsVisible(true);xylineandshaperenderer.setBasePositiveItemLabelPosition(newItemLabelPosition(ItemLabelAnchor.OUTSIDE12,TextAnchor.BASELINE_CENTER));xylineandshaperenderer.setBaseItemLabelGenerator(newStandardXYItemLabelGenerator());xylineandshaperenderer.setBaseItemLabelPaint(newColor(102,102,102));//顯示折點數值字體的顏色returnjfreechart;}

4、將圖片URL返回到頁面

publicstaticvoiddrawPressLineChart(IrisIoInterfaceio,Loglog,TimeSeriesCollectiontimesers,intweekormonth,Stringtitle,Stringy,Stringindex,Stringweek,Stringyear,intsearchby,Stringmonth,Stringnodatamess,Listlist,Stringbp_shou,Stringbp_shuzhang){JFreeChartchart=createChartPress(timesers,weekormonth,title,y,index,week,year,searchby,month,nodatamess,list,log,bp_shou,bp_shuzhang);HttpServletRequestrequest=io.getRequest();Stringfilename="";StringgraphURL="";try{filename=ServletUtilities.saveChartAsPNG(chart,650,280,null,io.getSession());graphURL=request.getContextPath()+"/displayChart?filename="+filename;}catch(IOExceptione){//TODOAuto-generatedcatchblocke.printStackTrace();log.error(e);}io.setData("filename1",filename,BeanShare.BEAN_SHARE_REQUEST);io.setData("presslineurl",graphURL,BeanShare.BEAN_SHARE_REQUEST);}

效果圖如下：

以天為刻度：

以周為刻度：

以月為刻度：

總結

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