一个C#项目，想要的结果没有出来，帮忙看看。

Question

创建一个在后台运行的Windows服务程序，该程序启动时，创建并启功一个线程。该线程启动后，产生
一个定时器，定时器会每隔10秒定时对数据库中的库存表进行扫描，如果某物料或商品的当前数量小于
或等于安全库存量，则将该物料的相关报警信息写入日志文件中。我发现无论如何改变库存表中的信息，login.txt日志文件没有任何记录，为什么？
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.ServiceProcess;
using System.Text;
using System.Threading;
using System.Timers;
using System.Data.SqlClient;
 
using System.IO;
namespace experiment8_1
{
   
    public partial class Service1 : ServiceBase
    {
        private System.Timers.Timer timer;
        private Thread scanThread;
        private SqlConnection conn;
        private SqlCommand comm;
        private FileStream fs;
        public Service1()
        {
            InitializeComponent();
        }        protected override void OnStart(string[] args)
        {
            // TODO: 在此处添加代码以启动服务。
            scanThread = new Thread(new ThreadStart(ScanMaterial));
            scanThread.Start();
        }
        private void ScanMaterial()
        {
            if (timer == null)
            {
                timer = new System.Timers.Timer();
                timer.Interval = 10000;
                timer.Enabled = true;
                timer.Elapsed += new ElapsedEventHandler(OnTimer);            }
            else
            {
                timer.Start();
            }
        
        
        }
        private void OnTimer(Object source, ElapsedEventArgs e)
        {
            string strConn = "Server=.;Database=studentManagent;Integrated Security=sspi;";
            conn = new SqlConnection(strConn);
            string sql = "select safeQuan,onlineQuan,materialName from material";
            comm = new SqlCommand(sql, conn);
            try
            {
                fs = new FileStream(@"c:\liu.txt", FileMode.Create, FileAccess.Write);
                StreamWriter sw = new StreamWriter(fs, Encoding.Default);
                conn.Open();
                SqlDataReader dr = comm.ExecuteReader();
                while (dr.Read())
                {
                    if (dr.GetInt32(1) <= dr.GetInt32(0))
                    {
                        sw.BaseStream.Seek(0, SeekOrigin.End);
                        sw.WriteLine(string.Format("警告提示：日期：{0}", DateTime.Now.ToString()));
                        sw.WriteLine(string.Format("请及时补充{0},安全库存是{1},在线数量是{2}。", dr[2].ToString(), dr[0].ToString(), dr[1].ToString()));
                    }
                }
                sw.Flush();
                sw.Close();            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally 
            {
                conn.Close();
                fs.Close();
            }
        
        }
        protected override void OnStop()
        {
            // TODO: 在此处添加代码以执行停止服务所需的关闭操作。
            if (timer != null)
                timer.Close();
            if(scanThread!=null)
                scanThread.Abort();
        }
    }
}

Answer 1

只是数据库表的图片，里面有一些记录，希望能显示出来
这里的login.txt就是liu.txt
服务已安装，注册了

Answer 2

再次看了看,这里确实是java/java se发错区了吧?同志,出门右拐

Answer 3

  if (timer == null)
            {
                timer = new System.Timers.Timer();
                timer.Interval = 10000;
                timer.Enabled = true;
                timer.Elapsed += new ElapsedEventHandler(OnTimer);
              //如果为null的时候，这边怎么不再进行  timer.Start();   ???
            }
            else
            {
                timer.Start();
            }
   catch (Exception ex)
            {
                throw ex;
              //强烈建议这边也写日志到 txt文件里面去，windows服务你是没那么多精力去看服务是否被停止            }
//另外建议 这类作业程序使用第三方组件，更稳定更准确
//Quartz.net 自己搜索下

Answer 4

                while (dr.Read())
                {
                    if (dr.GetInt32(1) <= dr.GetInt32(0))
//上面这一句，不是应该改为第三列和第四列比较吗？

Answer 5

select safeQuan,onlineQuan,materialName from material
查询的 safeQuan，onlineQuan是一，二列
五楼的我不怎么懂

Answer 6

以后Windows不建议用Timer，这个不靠谱，你的线程已经执行完毕了，怎么可能还能计时呢？
我给你改改吧。
记得以后要加dr.Close();using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.ServiceProcess;
using System.Text;
using System.Threading;
using System.Timers;
using System.Data.SqlClient;using System.IO;
namespace experiment8_1
{    public partial class Service1 : ServiceBase, IDisposable
    {
        private Thread scanThread;
        private SqlConnection conn;
        private SqlCommand comm;
        private FileStream fs;
        private bool m_Running = false;        public Service1()
        {
            InitializeComponent();
        }        protected override void OnStart(string[] args)
        {
            // TODO: 在此处添加代码以启动服务。
            scanThread = new Thread(new ThreadStart(ScanMaterial));
            scanThread.IsBackground = true;
            m_Running = true;
            scanThread.Start();
        }
        private void ScanMaterial()
        {
            while (m_Running)
            {
                try
                {
                    string strConn = "Server=.;Database=studentManagent;Integrated Security=sspi;";
                    conn = new SqlConnection(strConn);
                    string sql = "select safeQuan,onlineQuan,materialName from material";
                    comm = new SqlCommand(sql, conn);
                    try
                    {
                        fs = new FileStream(@"c:\liu.txt", FileMode.Create, FileAccess.Write);
                        StreamWriter sw = new StreamWriter(fs, Encoding.Default);
                        conn.Open();
                        SqlDataReader dr = comm.ExecuteReader();
                        while (dr.Read())
                        {
                            if (dr.GetInt32(1) <= dr.GetInt32(0))
                            {
                                sw.BaseStream.Seek(0, SeekOrigin.End);
                                sw.WriteLine(string.Format("警告提示：日期：{0}", DateTime.Now.ToString()));
                                sw.WriteLine(string.Format("请及时补充{0},安全库存是{1},在线数量是{2}。", dr[2].ToString(), dr[0].ToString(), dr[1].ToString()));
                            }
                        }
                        dr.Close();
                        sw.Flush();
                        sw.Close();
                    }
                    catch (Exception ex)
                    {
                        throw ex;
                    }
                    finally
                    {
                        conn.Close();
                        fs.Close();
                    }
                }
                catch
                {
                }
                finally
                {
                    if (!m_Running)
                    {
                        break;
                    }
                    Thread.Sleep(60 * 1000);
                }
            }
        }        protected override void OnStop()
        {
            // TODO: 在此处添加代码以执行停止服务所需的关闭操作。
            m_Running = false;
            scanThread.Join();
        }
    }
}

Answer 7

是Windows Service不建议用Timer，少打了Service，呵呵

Answer 8

按加林仙人的代码
catch (Exception ex)
                    {
                        throw ex;
                    }
                    finally
                    {
                        conn.Close();
                        fs.Close();
                    }错误 1 控制不能离开 finally 子句主体 F:\作业\WinForm\experiment8-1\experiment8-1\Service1.cs 83 25 experiment8-1
自己改了一下，还是没有出来。

Answer 9

finally
                {
                    if (!m_Running)
                    {
                        break;
                    }
                    Thread.Sleep(60 * 1000);
                }