[英]c# stop eventhandler after timer stops
為什么即使在我停止計時器后,我的事件處理程序也永遠不會停止調用? 我的代碼有問題嗎? 請幫忙!
我把我的整個代碼包括在里面,如果你們能幫我一些幫助請:)
private void Form1_Load(object sender, EventArgs e)
{
//Start system
axInRFIDCtrl1.SelectReaderFeig();
axInRFIDCtrl1.FEInit();
short sResult = axInRFIDCtrl1.FEOpen();
//MessageBox.Show(sResult.ToString());
//Start timer1
System.Windows.Forms.Timer timer1 = new System.Windows.Forms.Timer();
timer1.Interval = 1000;
timer1.Tick += new EventHandler(timer1_Tick);
timer1.Enabled = true;
timer1.Start();
Console.ReadLine();
}
public void timer1_Tick(object sender, EventArgs e)
{
//Get ID
string strTagIds = string.Empty;
int iState = 0;
axInRFIDCtrl1.FESelect(ref strTagIds, ref iState);
string[] strTagID = strTagIds.Split(new char[] { '|' });
string strTag = strTagID[0];
textBox1.Text = strTag;
//Connection to datebase
string c1 = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Project.mdb";
OleDbConnection con = new OleDbConnection(c1);
//Bind button
string txt = textBox1.Text;
string strOleDbConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Project.mdb";
string strSqlStatement = string.Empty;
strSqlStatement = "SELECT * FROM jiahe WHERE [Tag ID] = '" + txt + "'";
OleDbConnection objConnection = new OleDbConnection(strOleDbConnectionString);
OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSqlStatement, objConnection);
DataSet ds = new DataSet();
objAdapter.Fill(ds);
DataTable dt = ds.Tables[0];
dataGridView1.DataSource = dt.DefaultView;
if (dt.Rows.Count == 1)
{
string strLine = string.Empty;
string strUser = string.Empty;
foreach (DataRow dr in dt.Rows)
{
string strTags = dr["Tag ID"].ToString();
strUser = dr["User"].ToString();
string strAge = dr["Age"].ToString();
string strPhoneNumber = dr["Phone Number"].ToString();
// prepare command string
string selectString = @"SELECT Status FROM jiahe where [Tag ID] = '" + textBox1.Text + "'";
// 1. Instantiate a new command with command text only
OleDbCommand cmd = new OleDbCommand(selectString, objConnection);
// 2. Set the Connection property
cmd.Connection.Open();
// 3. Call ExecuteScalar to send command
string str = cmd.ExecuteScalar().ToString();
cmd.Connection.Close();
foreach (DataRow datarow in dt.Rows)
{
//string strName = string.Empty;
strName = datarow["User"].ToString();
if (str.Length == 2 || str.Length == 0)
{
// prepare command string
string updateString = @"update jiahe set Status = 'OUT' where [Tag ID] = '" + textBox1.Text + "'";
// 1. Instantiate a new command with command text only
OleDbCommand cmd1 = new OleDbCommand(updateString, objConnection);
// 2. Set the Connection property
cmd1.Connection.Open();
// 3. Call ExecuteNonQuery to send command
str = cmd1.ExecuteNonQuery().ToString();
cmd1.Connection.Close();
//write text file to outgoing spool
//TextWriter tw = new StreamWriter(@"C:\cygwin\var\spool\sms\outgoing\sms.txt");
TextWriter tw = new StreamWriter(@"C:\\Test.txt");
{
tw.WriteLine("To: 6592786618\n");
tw.WriteLine("\n");
tw.WriteLine("\n" + strName + @" has just left at " + DateTime.Now);
tw.Close();
}
MessageBox.Show(strName + " has left the house.");
//Start timer2
System.Windows.Forms.Timer timer2 = new System.Windows.Forms.Timer();
timer2.Interval = 1000 * 60 * 30; //30 mins interval
timer2.Tick += new EventHandler(timer2_Tick);
timer2.Enabled = true;
timer2.Start();
//Log to listbox
// Set the selection mode to multiple and extended.
listBox1.SelectionMode = SelectionMode.MultiExtended;
listBox1.BeginUpdate();
listBox1.Items.Add(DateTime.Now + " - " + strName + " > OUT");
listBox1.EndUpdate();
//Log event to log file
string cs = "Minder+Finder Event Log";
EventLog elog = new EventLog();
if (!EventLog.SourceExists(cs))
{
EventLog.CreateEventSource(cs, cs);
}
elog.Source = cs;
elog.EnableRaisingEvents = true;
elog.WriteEntry(DateTime.Now + " - " + strName + " > OUT");
}
else
{
// prepare command string
string updateString = @"update jiahe set Status = 'IN' where [Tag ID] = '" + textBox1.Text + "'";
// 1. Instantiate a new command with command text only
OleDbCommand cmd1 = new OleDbCommand(updateString, objConnection);
// 2. Set the Connection property
cmd1.Connection.Open();
// 3. Call ExecuteNonQuery to send command
str = cmd1.ExecuteNonQuery().ToString();
cmd1.Connection.Close();
//write text to outgoing spool
TextWriter tw = new StreamWriter(@"C:\\Test.txt");
//using (TextWriter tw = File.CreateText("C:\cygwin\var\spool\sms\outgoing\Test.txt"));
{
tw.WriteLine("To: 6592786618\n");
tw.WriteLine("\n");
tw.WriteLine("\n" + strName + @" has just returned home at " + DateTime.Now);
tw.Close();
}
MessageBox.Show(strName + " has returned home.");
//Stop timer2
timer2.Tick -= timer2_Tick;
timer2.Enabled = false;
timer2.Stop();
//Log to listbox
// Set the selection mode to multiple and extended.
listBox1.SelectionMode = SelectionMode.MultiExtended;
listBox1.BeginUpdate();
listBox1.Items.Add(DateTime.Now + " - " + strName + " > IN");
listBox1.EndUpdate();
//Log event to log file
string cs = "Minder+Finder Event Log";
EventLog elog = new EventLog();
if (!EventLog.SourceExists(cs))
{
EventLog.CreateEventSource(cs, cs);
}
elog.Source = cs;
elog.EnableRaisingEvents = true;
elog.WriteEntry(DateTime.Now + " - " + strName + " > IN");
}
}
}
}
else
{
timer1.Enabled = false;
}
}
private void button1_Click(object sender, EventArgs e)
{
Form2 form2 = new Form2();
form2.ShowDialog();
}
private void button2_Click(object sender, EventArgs e)
{
Form3 form3 = new Form3();
form3.ShowDialog();
}
public void timer2_Tick(object sender, EventArgs e)
{
MessageBox.Show(strName + " has left");
//write text file to outgoing spool
//TextWriter tw = new StreamWriter(@"C:\cygwin\var\spool\sms\outgoing\sms.txt");
TextWriter tw = new StreamWriter(@"C:\\Test1.txt");
{
tw.WriteLine("To: 6592786618\n");
tw.WriteLine("\n");
tw.WriteLine("\n" + strName + @" has just left at " + DateTime.Now);
tw.Close();
}
}
如果你停止計時器(通過調用Stop()
或設置Enabled = false
),它將不會再次觸發。 我從未見過停止計時器調用事件處理程序的情況。 如果在禁用計時器后仍然調用事件處理程序,則其他一些代碼正在調用它,或者某些東西正在重新啟用計時器。
另請注意,如果事件處理程序當前正在執行,則停止計時器不會中止事件。 它也不會阻止任何未決事件。 雖然這不應該是System.Windows.Forms.Timer
的問題,因為它的事件處理程序總是在GUI線程上執行。
如果我是你,我會仔細檢查代碼並查看啟用或禁用計時器的所有位置。 我懷疑你會發現你的代碼中有一些東西會重新啟用計時器。
看到您發布的代碼后編輯:
可能問題是你的計時器事件處理程序中有以下內容:
System.Windows.Forms.Timer timer2 = new System.Windows.Forms.Timer();
// code that initializes and enables timer
這會創建一個本地timer2
變量,它與你在表單范圍內的timer2
不同(我假設,因為你暗示代碼編譯,你在一個單獨的范圍內引用timer2
)。 您最終創建了一個新計時器,但禁用計時器的代碼引用了表單范圍timer2
。 所以正在發生的是你正在創建許多不同的計時器,並且每個計時器最終都會調用相同的事件處理程序。
我希望你在事件處理程序中調用MessageBox.Show
只是為了調試目的。 你不想把它們留在那里,因為它們阻止了UI線程並且會阻止額外的計時器滴答,直到它們被解雇。
如果timer2是一個實例變量,那么問題是你正在創建一個名為timer2的局部變量並啟動它。 然后,您將停止成員變量timer2,而不是本地作用域timer2。 本地范圍timer2將繼續觸發,直到垃圾收集器繞過它來處理它。
我很確定timer2是一個實例變量,否則對它的其他引用將無法編譯。 還要注意,因為你在循環中創建了timer2,你可能正在創建它們中的一大堆,並且所有這些都快樂地開火,直到垃圾收集器將它們排除在他們的痛苦之外。
編輯:這是一個在Form中使用的一個相當簡單的例子。
http://www.java2s.com/Code/CSharp/GUI-Windows-Form/GUIandtimer.htm
如果您只是將計時器組件放到表單設計中,那么將在InitializeComponents方法中為您編寫初始化,如本例所示。 除此之外,我無法忍受更多。 我認為你嘗試使用計時器的方式存在一些結構性問題。 所有的啟動和停止,特別是對於循環中的timer2似乎會導致你很麻煩和頭痛。
您的停止代碼會更好:
//Stop timer2
timer2.Stop();
timer2.Tick -= timer2_Tick;
至於你真正的問題......我們需要看到你的其余代碼來幫助你。
這樣編寫的代碼永遠不會觸發定時器,因為它會在時間流逝之前(以三種不同的方式)被阻止。
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