webform1.aspx.cs

Csharp实例编程百例.rar

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.OleDb;
using System.Drawing.Imaging;


namespace UserPoll
{
	/// <summary>
	/// WebForm1 的摘要说明。
	/// </summary>
	public class WebForm1 : System.Web.UI.Page
	{
		protected System.Web.UI.WebControls.RadioButtonList rlCandidates;
		protected System.Web.UI.WebControls.Button btnVote;
		protected System.Web.UI.WebControls.Image Image1;

		private OleDbConnection conn;
		private DataSet ds = new DataSet ();
		private string connstr = "";

		private void Page_Load(object sender, System.EventArgs e)
		{
			// 在此处放置用户代码以初始化页面
			
			//初始化数据库连接string
			connstr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" 
				+ Server.MapPath(@".\db\polldb.mdb") 
				+ ";Mode=Share Deny None;Persist Security Info=False";
			if (!IsPostBack)
			{
				BindData();
			}
		}

		private void BindData()
		{
			//new a dbconnection，数据库为db目录下的polldb.mdb

			conn = new OleDbConnection(connstr); 
			//创建sql语句
			string sql = "SELECT * FROM [datatbl]";
			//创建dataadapter
			OleDbDataAdapter da = new OleDbDataAdapter(sql,conn); 
			//填充dataset
			da.Fill(ds,"Data");
			//给RadioButtonList赋数据
			InitRadioButtonList();
			//绘制饼状图
			DrawResult();
		}

		private void InitRadioButtonList()
		{
			//将DataSet数据绑定到RadioButtonList
			rlCandidates.DataSource = ds.Tables["Data"] ;
			rlCandidates.DataTextField = ds.Tables["Data"].Columns["name"].ToString ();
			rlCandidates.DataValueField = ds.Tables["Data"].Columns["count"].ToString ();
			rlCandidates.DataBind ();
		}

		private void DrawResult()
		{
			//创建一个Bitmap
			Bitmap bm = new Bitmap(200,200);
			//得到Graphics
			Graphics g = Graphics.FromImage(bm);
			g.Clear (Color.White);
			//统计总投票数
			int totalCount=0;
			foreach (DataRow aRow in ds.Tables["Data"].Rows )
			{
				totalCount += int.Parse (aRow["count"].ToString ());
			}
			
			int startangle = 0;	//扇形起始角度
			int sweepangle;		//扇形跨越角度
			foreach (DataRow aRow in ds.Tables["Data"].Rows)
			{
				string sname = aRow["name"].ToString();
				string scount = aRow["count"].ToString() ;
				string sindex = aRow["index"].ToString() ;
				//选取不同颜色
				Color c = getColor(int.Parse(sindex)) ;

				sweepangle = (int)Math.Round (double.Parse(scount)/totalCount*360);
				Brush myBrush = new SolidBrush(c); 
				//调用FillPie绘制扇形
				g.FillPie(myBrush,0,0,200,200,startangle,sweepangle);
				startangle += sweepangle;
				//输出文字解释
				Response.Write (sname + ":" + scount + " 颜色：" + c.ToString() + "<br> ");
			}
			//保存为临时文件
			bm.Save(Server.MapPath (@".\result.jpeg"), ImageFormat.Jpeg );
			//将Image控件的图像链接到此文件
			Image1.ImageUrl = Server.MapPath (@".\result.jpeg");
		}
		//根据序号，返回不同颜色
		private Color getColor(int index)
		{
			Color c;
			int i = index % 5;
			switch(i)
			{
				case 0:
					c = Color.Red;
					break;
				case 1:
					c = Color.Blue ;
					break;
				case 2:
					c = Color.Yellow ;
					break;
				case 3:
					c = Color.Green;
					break;
				case 4:
					c = Color.Gray;
					break;
				default: 
					c = Color.Black ;
					break;
			}
			return (c);
		}

		#region Web Form Designer generated code
		override protected void OnInit(EventArgs e)
		{
			//
			// CODEGEN：该调用是 ASP.NET Web 窗体设计器所必需的。
			//
			InitializeComponent();
			base.OnInit(e);
		}
		
		/// <summary>
		/// 设计器支持所需的方法 - 不要使用代码编辑器修改
		/// 此方法的内容。
		/// </summary>
		private void InitializeComponent()
		{    
			this.btnVote.Click += new System.EventHandler(this.btnVote_Click);
			this.Load += new System.EventHandler(this.Page_Load);

		}
		#endregion

		private void btnVote_Click(object sender, System.EventArgs e)
		{
			if (rlCandidates.SelectedItem != null)
			{
				//new a dbconnection，数据库为db目录下的polldb.mdb
				conn = new OleDbConnection(connstr); 
				conn.Open ();
				//Update记录，count＝count＋1
				string sql = "UPDATE [datatbl] SET [count]=" + Convert.ToString ((int.Parse (rlCandidates.SelectedItem.Value)  + 1)) 
					        + " WHERE [name]='" + rlCandidates.SelectedItem.Text + "'" ;
				OleDbCommand cmd = new OleDbCommand(sql,conn);
				cmd.ExecuteNonQuery ();
				conn.Close ();
				//更新数据显示
				BindData();
			}
		}
	}
}