一个图表练习
使用代码：
chart.setPoints(points);
String str[] = new String[]{"20", "15", "10", "5", "0"};
chart.setXst(str);
String str2[] = new String[]{"20", "21", "22", "23", "24", "25", "26", "27"};//个数应和point点数相同
chart.setYst(str2);
chart.setType(CurveChart.TYPE.FOLD);//默认曲线，此为折线
