1
嗨我正在使用winform並嘗試使用MessageBox進行異常處理。 這裏奇怪的是，MessageBox只有在主窗體（下面的代碼中的「Form1」）被關閉後纔會出現。使用MessageBox在多線程應用程序中顯示異常信息
public class Worker {
/* edited (see below)
public void doWork() {
try {
// do something
client.Connect(serverAddress);
stream = client.GetStream();
}
catch(Exception e) {
MessageBox.Show(e.ToString(),
"This will not show up until Form1 is closed");
}
}
*/
}
public class Form1 {
/* edited (see below)
* public void threadProc() {
* Worker worker = new Worker();
* worker.doWork();
* }
*/
void button_Click(object sender, EventArgs e) {
// create a thread that will end up throwing an exception
Thread thread = new Thread(threadProc);
thread.Start();
}
}
什麼可能是一個更好的方式來使用MessageBox進行異常處理？
...所以我加了一些代碼的MessageBox-ING在UI線程，但問題仍然存在。
public class WorkExceptionArgs : EventArgs {
public Exception e;
public WorkExceptionArgs (Exception e) { this.e = e; }
}
public partial class Worker1 { // renamed (Worker->Worker1)
/* (edited) Now Worker1 doesn't trigger any event (see below)
public event EventHandler<WorkExceptionArgs> workException;
*/
public void doWork() {
try {
// do something
client.Connect(serverAddress);
stream = client.GetStream();
}
catch(Exception e) {
/* (edited) suppose Worker1 never throws any exception (see below)
* // trigger event that will cause MessageBox-ing by UI thread
* workException(this, new WorkExceptionArgs(e));
*/
}
}
}
public partial class Form1 {
public void threadProc() {
Worker1 worker1 = new Worker();
/* (edited) Now Worker1 never throws any exception
* worker.workException += new EventHandler<WorkException>(worker_WorkException);
*/
worker1.doWork();
// (added) After doWork() is done, Form1 creates Worker2
Worker2 w2 = new Worker2(this, this.form2);
w2.workException += new EventHandlerArgs<WorkExceptionArgs>(form2.worker2_WorkException);
w2.doSomeOtherWork();
}
/* public void worker_WorkException(object sender, WorkExceptionArgs eArg) {
* MessageBox.Show(eArg.e.ToString(), "Still not showing");
* } */
Form2 form2 = new Form2(); // (added) At first form2 is hidden (see below)
}
其實已經出現了另一種形式和另一名工人。一旦Worker（Worker1）連接到服務器，Form1隱藏（.Hide（）），Form2顯示（.Show（）），並且Worker2開始使用連接Worker1創建。
public class Worker2 {
Worker2(Worker1 w1, Form2 frm2) { this.w1=w1; this.frm2=frm2; }
public Worker1 w1;
public Form2 frm2;
public event EventHandler<WorkExceptionArgs> workException;
public void doSomeOtherWork() { // do some other, using data in Worker 1.
try { // This will throw an exception
BinaryFormatter formatter = new BinaryFormatter();
MyObj mo = (MyObj)formatter.Deserialize(w1.getStream());
}
catch(Exception e) {
workException(this, new WorkExceptionArgs(e));
}
}
}
public class Form2 {
public Form2(Form1 frm1) { // to switch from frm1 to frm2
InitializeComponent();
this.frm1 = frm1;
}
public Frm1 frm1 {get;set;}
public void worker2_WorkException(object sender, WorkExceptionArgs ea) {
MessageBox.Show(this, ea.e.ToString(), "SHOWS ONLY IF FORM2 IS CLOSED");
}
}
public partial class Form1 {
delegate void switchWindow_Callback();
public void switchWindow() { this.Hide(); form2.Show(); }
public void switchWindowCb(object sender, EventArgs e) {
if(this.InvokeRequired) {
SwitchWindow_Callback hcb = new SwitchWindow_Callback(switchWindow);
this.Invoke(hcb, new object[] {});
}
else { this.switchWindow(); }
}
}
你是否在調試模式下逐步完成了代碼？ – Derek