c# - 阅读器只在while循环C#中拉一行

Question

我有两个问题。一是在有几百个要发送的情况下，它只拉一排并发送到ms传真。另一个是它在此之后不再拉动并引发错误。我以为我正在关闭我的联系。我不明白问题是什么。我已经包含了代码和错误。

服务1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Linq;
using System.ServiceProcess;
using System.Text;
using System.Timers;
using MySql.Data.MySqlClient;
using FAXCOMLib;
using FAXCOMEXLib;

namespace ProcessFaxes
{
public partial class Service1 : ServiceBase
{
    public Service1()
    {
        InitializeComponent();
    }
    public static Timer timer = new Timer();

    protected override void OnStart(string[] args)
    {

        timer.Elapsed += new ElapsedEventHandler(Tick);
        timer.Interval = 600000; // every 10 minutes
        timer.Enabled = true;
       // Console.ReadLine();
     }

    protected override void OnStop()
    {

    }

    public static void Tick(object source, ElapsedEventArgs e)
    {
        string connString = "Server=localhost;Port=3306;Database=communications;Uid=root;password=pass;";
        MySqlConnection conn = new MySqlConnection(connString);
        MySqlCommand command = conn.CreateCommand();

        MySqlConnection connupdate = new MySqlConnection(connString);
        MySqlCommand commandupdate = connupdate.CreateCommand();

        command.CommandText = "SELECT * FROM outbox WHERE `faxstat` = 'Y' AND `fax` <> '' AND `faxpro` = 'PENDING'";
        //command.CommandText = "UPDATE blah blah";
        //conn.Open();
        //conn.ExecuteNonQuery();
        //conn.Close();

        try
        {

            conn.Open();
            connupdate.Open();

        }
        catch (Exception ex)
        {
            // Console.WriteLine(Ex.Message); 
                LogException(ex.ToString());

        throw;  // or whatever you want to do with it
        }
        MySqlDataReader reader = command.ExecuteReader();

        if (reader.HasRows)
        {

            while (reader.Read())
            {
                //Console.WriteLine(reader["filepath"].ToString());
                SendFax(reader["id"].ToString(), reader["filepath"].ToString(), @"C:\FAXDOC\" + reader["filepath"].ToString(), reader["account"].ToString(), reader["fax"].ToString(), reader["fax_orig"].ToString());
                string id = reader["id"].ToString();
                commandupdate.CommandText = "UPDATE outbox SET `faxpro` = 'DONE' WHERE `id` = '" + id + "'";
                commandupdate.ExecuteNonQuery();

            }
        }

        conn.Close();
        connupdate.Close();
    }

    public static void SendFax(string DocumentId, string DocumentName, string FileName, string RecipientName, string FaxNumber, string RecipientHomePhone2)
    {
        if (FaxNumber != "")
        {
            try
            {
                FAXCOMLib.FaxServer faxServer = new FAXCOMLib.FaxServerClass();
                faxServer.Connect(Environment.MachineName);


                FAXCOMLib.FaxDoc faxDoc = (FAXCOMLib.FaxDoc)faxServer.CreateDocument(FileName);

                faxDoc.RecipientName = RecipientName;
                faxDoc.FaxNumber = FaxNumber;
                faxDoc.BillingCode = DocumentId;
                faxDoc.DisplayName = DocumentName;
                faxDoc.RecipientHomePhone = RecipientHomePhone2;

                int Response = faxDoc.Send();


                faxServer.Disconnect();

            }
            catch (Exception Ex) { 

               // Console.WriteLine(Ex.Message); 
                LogException(Ex.ToString());

        throw;  // or whatever you want to do with it
            }
        }



    }

    public static void LogException(string ErrorDescription)

    {

        // The name of our log in the event logs

        string Log = "Process Faxes";



        // Check to see fi the log for AspNetError exists on the machine

        //          If not, create it

        if ((!(EventLog.SourceExists(Log))))

        {


EventLog.CreateEventSource(Log, Log);

        }



        // Now insert your exception information into the AspNetError event log

        EventLog logEntry = new EventLog();

        logEntry.Source = Log;

        logEntry.WriteEntry(ErrorDescription, EventLogEntryType.Error);

        }


    }
}

错误

Event Type: Error
Event Source:   Process Faxes
Event Category: None
Event ID:   0
Date:       3/6/2012
Time:       2:01:06 PM
User:       N/A
Computer:   FAXSERVER
Description:
MySql.Data.MySqlClient.MySqlException (0x80004005): Too many connections
   at MySql.Data.MySqlClient.MySqlStream.ReadPacket()
   at MySql.Data.MySqlClient.NativeDriver.Open()
   at MySql.Data.MySqlClient.Driver.Open()
   at MySql.Data.MySqlClient.Driver.Create(MySqlConnectionStringBuilder settings)
   at MySql.Data.MySqlClient.MySqlPool.GetPooledConnection()
   at MySql.Data.MySqlClient.MySqlPool.TryToGetDriver()
   at MySql.Data.MySqlClient.MySqlPool.GetConnection()
   at MySql.Data.MySqlClient.MySqlConnection.Open()
   at ProcessFaxes.Service1.Tick(Object source, ElapsedEventArgs e) in C:\Documents and Settings\bruser\My Documents\Visual Studio 2010\Projects\ProcessFaxes\ProcessFaxes\Service1.cs:line 56

score 2 · Accepted Answer

我认为你应该重构一下。我在上面的评论中解释了一点，但这是我将如何改变它（我也为你添加了一些评论）：

public static void Tick(object source, ElapsedEventArgs e)
{
    // Prevent another Tick from happening if this takes longer than 10 minutes
    (source as Timer).Enabled = false;

    // It would be better practice to put this in a settings or config file
    // so you can change it without having to recompile your application
    string connString = "Server=localhost;Port=3306;Database=communications;Uid=root;password=pass;";

    // I won't change them here, but since these classes implement IDisposable,
    // you should be using a using statement around them:
    // using (var conn = new MySqlConnection(connString))
    // {
    //     // use conn
    // }
    MySqlConnection conn = new MySqlConnection(connString);
    MySqlCommand command = conn.CreateCommand();
    MySqlCommand updateCommand = conn.CreateCommand();

    command.CommandText = "SELECT * FROM outbox WHERE `faxstat` = 'Y' AND `fax` <> '' AND `faxpro` = 'PENDING'";

    try
    {
        conn.Open();

        MySqlDataReader reader = command.ExecuteReader();

        if (reader.HasRows)
        {
            while (reader.Read())
            {
                SendFax(reader["id"].ToString(), reader["filepath"].ToString(), @"C:\FAXDOC\" + reader["filepath"].ToString(), reader["account"].ToString(), reader["fax"].ToString(), reader["fax_orig"].ToString());
                string id = reader["id"].ToString();
                // I would use a prepared statement with either this query
                // or a stored procedure with parameters instead of manually
                // building this string (more good practice than worrying about
                // SQL injection as it's an internal app
                updateCommand.CommandText = "UPDATE outbox SET `faxpro` = 'DONE' WHERE `id` = '" + id + "'";
                updateCommand.ExecuteNonQuery();

            }
        }
    }
    catch (Exception ex)
    {
        LogException(ex.ToString());
        throw;
    } 
    finally 
    {
        // If you're not going to use using-statements, you might want to explicitly
        // call dispose on your disposable objects:
        // command.Dispose();
        // updateCommand.Dispose();
        conn.Close();
        // conn.Dispose();
    }

    // Enable the timer again
    (source as Timer).Enabled = true;
}

至于为什么当你期待很多时你只收到一行，我怀疑你的 SQL 有问题。

score 0 · Accepted Answer

您不应该使用计时器。

计时器会定期触发，并且不关心前一个事件是否已完成。

考虑使用后台工作人员发送传真，让它在队列中循环，然后在队列为空时暂停。

score 0 · Accepted Answer

问题在于您的连接对象。您已经定义了几个连接对象。你只需要一个。

以下是有问题的两个：

MySqlConnection connupdate = new MySqlConnection(connString);

MySqlConnection conn = new MySqlConnection(connString);

消除与其中之一的连接。

这是修复代码的一种方法：

string connString = "Server=localhost;Port=3306;Database=communications;Uid=root;password=pass;";

using(MySqlConnection conn = new MySQLConnection(connString))
   {
   using(MySQlCommand command = conn.CreateCommand())
     {
      command.CommandText = "SELECT ...";
      conn.Open();
      using(MySqlDataReader reader = command.ExecuteReader())
           {
             //process rows...
           }
     }
   }

c# - 阅读器只在while循环C#中拉一行

3 回答 3

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