异步调用问题
我在写数据库程序时，希望能够将很多的结果一次返回，因而采用了异步调用，但在调用过程中，要么界面没有任何反应，要么有时出现下列错误：末处理INVALIDOPERATIONEXCEPTION 。不知何因，；界面只有一DATABINDVIEW1与BUTTON1。代码如下：请各位高手指点迷津，已经搞了几天了，都没有搞好。
BUTTON1单击：
dbrecordholder =new ArrayList();
string connectstring = "asynchronous processing=true;Password=123;Persist Security Info=True;User ID=sa;Initial Catalog=demo;Data Source=127.0.0.1";
using (SqlConnection testconnection = new SqlConnection(connectstring))
{
SqlCommand textcommand = new SqlCommand("select * from uname", testconnection);
testconnection.Open();
//SqlDataReader sqldr = textcommand.ExecuteReader(CommandBehavior.CloseConnection);
//if (sqldr.HasRows)
//{
// foreach (DbDataRecord rec in sqldr)
// {
// dbrecordholder.Add(rec);
// }
//}
//sqldr.Close();
AsyncCallback callback = new AsyncCallback(datareaderisready);
IAsyncResult asyncresult= textcommand.BeginExecuteReader(callback, textcommand);
dataGridView1.DataSource = dbrecordholder;
bindingSource1.DataSource = dbrecordholder;
bindingNavigator1.BindingSource = bindingSource1;
datareaderisready过程：
private void datareaderisready(IAsyncResult result)
{
MessageBox.Show("result load complete", "i'm done");
SqlCommand testcommand = (SqlCommand)result.AsyncState;
//testcommand.Connection.Open();
SqlDataReader sqldr = testcommand.EndExecuteReader(result);
if (sqldr.HasRows)
{
foreach (DbDataReader rec in sqldr)
{
dbrecordholder.Add(rec);
}
}
sqldr.Close();
testcommand.Connection.Dispose();
}
跪求解决方法
[解决办法]
using (SqlConnection testconnection = new SqlConnection(connectstring))
{
}
执行后连接已关闭。
private void button1_Click(object sender, EventArgs e)
{
SqlConnection testconnection = new SqlConnection(connectstring);
SqlCommand textcommand = new SqlCommand("select * from Addr_First_Table", testconnection);
testconnection.Open();
AsyncCallback callback = new AsyncCallback(datareaderisready);
IAsyncResult asyncresult = textcommand.BeginExecuteReader(callback, textcommand);
}
private void datareaderisready(IAsyncResult result)
{
// MessageBox.Show("result load complete", "i 'm done");
SqlCommand testcommand = (SqlCommand)result.AsyncState;
//testcommand.Connection.Open();
SqlDataReader sqldr = testcommand.EndExecuteReader(result);
if (sqldr.HasRows)
{
}
sqldr.Close();
}
