GDI+ 绘制折线图分析网站流量
绘制折线图分析网站流量
折线图是网站开发中经常用到的一种图表技术，折线图可以很直观地反映出相关数据的变化趋势。本节通过一个实例来介绍如何使用折线图分析网站的流量。实例运行结果如图1所示。
程序开发步骤如下所示。
（1）新建一个网站，命名为26_03，其主页默认为Default.aspx。
（2）在该网站中添加一个Info.aspx页面，该页面主要用来使用折线图显示各月份的网站访问人数。
（3）程序主要代码如下。
图1 折线图分析网站流量
Info.aspx页面中定义了一个方法CreateImage，该方法主要用来从数据库中提取数据，并根据提取的数据，调用Graphics对象的相关方法绘制一张反映网站流量情况的折线图。CreateImage方法实现代码如下：
private void CreateImage(int P_int_year)
{
int height = 400, width = 600;
Bitmap image = new Bitmap(width, height);
Graphics graphics = Graphics.FromImage(image);
try
{
graphics.Clear(Color.White);
Font font = new Font("Arial", 9, FontStyle.Regular);
Font font1 = new Font("宋体", 20, FontStyle.Regular);
LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.Blue, 1.2f, True);
graphics.FillRectangle(Brushes.WhiteSmoke, 0, 0, width, height);
Brush brush1 = new SolidBrush(Color.Blue);
string P_str_sum = "SELECT * FROM tb_03 WHERE yearID=" + P_int_year + "";
SqlConnection sqlcon = new SqlConnection(ConfigurationManager.AppSettings["connectionString"]);
sqlcon.Open();
SqlCommand sqlcom = new SqlCommand(P_str_sum, sqlcon);
SqlDataReader sqlread = sqlcom.ExecuteReader(CommandBehavior.CloseConnection);
sqlread.Read();
if (sqlread.HasRows)
{
graphics.DrawString("" + P_int_year + "年各月份网站访问人数", font1, brush1, new PointF(130, 30));
}
sqlread.Close();
//画图片的边框线
graphics.DrawRectangle(new Pen(Color.Blue), 0, 0, image.Width - 1, image.Height - 1);
Pen mypen = new Pen(brush, 1);
//绘制横向线条
int x = 100;
for (int i = 0; i < 11; i++)
{
graphics.DrawLine(mypen, x, 80, x, 340);
x = x + 40;
}
Pen mypen1 = new Pen(Color.Blue, 2);
Pen mypen2 = new Pen(Color.Red, 2);
graphics.DrawLine(mypen1, x - 480, 80, x - 480, 340);
//绘制纵向线条
int y = 106;
for (int i = 0; i < 9; i++)
{
graphics.DrawLine(mypen, 60, y, 540, y);
y = y + 26;
}
graphics.DrawLine(mypen1, 60, y, 540, y);
//x轴
String[] n = {" 一月", " 二月", " 三月", " 四月", " 五月", " 六月", " 七月",
" 八月", " 九月", " 十月", "十一月", "十二月"};
x = 35;
for (int i = 0; i < 12; i++)
{
graphics.DrawString(n[i].ToString(), font, Brushes.Red, x, 348); //设置文字内容及输出位置
x = x + 40;
}
//y轴
String[] m = { " 900人", " 800人", " 700人", " 600人", " 500人", " 400人", " 300人",
" 200人", " 100人", " 0人"};
y = 98;
for (int i = 0; i < 10; i++)
{
graphics.DrawString(m[i].ToString(), font, Brushes.Red, 20, y); //设置文字内容及输出位置
y = y + 26;
}
int[] Count = new int[12];
string P_str_yearID = "SELECT * FROM tb_03 WHERE yearID=" + P_int_year + "";
SqlDataAdapter myda = new SqlDataAdapter(P_str_yearID, sqlcon);
DataSet myds = new DataSet();
myda.Fill(myds);
for (int j = 0; j < 12; j++)
{
Count[j] = Convert.ToInt32(myds.Tables[0].Rows[0][j + 1].ToString()) * 26 / 100;
}
SolidBrush mybrush = new SolidBrush(Color.Red);
Point[] myPoint = new Point[12];
myPoint[0].X = 60; myPoint[0].Y = 340 - Count[0];
myPoint[1].X = 100; myPoint[1].Y = 340 - Count[1];
myPoint[2].X = 140; myPoint[2].Y = 340 - Count[2];
myPoint[3].X = 180; myPoint[3].Y = 340 - Count[3];
myPoint[4].X = 220; myPoint[4].Y = 340 - Count[4];
myPoint[5].X = 260; myPoint[5].Y = 340 - Count[5];
myPoint[6].X = 300; myPoint[6].Y = 340 - Count[6];
myPoint[7].X = 340; myPoint[7].Y = 340 - Count[7];
myPoint[8].X = 380; myPoint[8].Y = 340 - Count[8];
