class ClassA
{
public delegate void WriteLog(string msg);
private WriteLog m_WriteLogDelegate;
public ClassA(WriteLog writelog)
{
m_WriteLogDelegate = writelog;
Thread thread = new Thread(new ThreadStart(Search));
thread.Start();
}
public void Search()
{
/* ... */
m_WriteLogDelegate("msg");
/* ... */
}
}
class classB
{
private ClassA m_classA;
protected void WriteLogCallBack(string msg)
{
// prints msg
/* ... */
}
public classB()
{
m_classA = new ClassA(new WriteLog(WriteLogCallBack));
}
public void test1()
{
Thread thread = new Thread(new ThreadStart(Run));
thread.Start();
}
public void test2()
{
m_classA.Search();
}
public void Run()
{
while(true)
{
/* ... */
m_classA.Search();
/* ... */
Thread.Sleep(1000);
}
}
}
为什么以下代码
ClassB b = new ClassB(); b.test2()
打印“msg”
还有这个
ClassB b = new ClassB(); b.test1()
什么都不打印？
解决方法
您的程序可能会退出,导致线程被终止(或者在线程有时间启动之前).就像你明确创建一个线程一样,你需要显式等待线程完成！
您需要使用Thread.Join或其他一些方法来保持主程序等待线程完成.
一个可能的选择,使用Thread.Join：
public Thread test2()
{
...
return thread;
}
...
b.test2().Join(); // wait for test2 to complete
另一个选项,使用ManualResetEvent：
class classB
{
private ManualResetEvent mre = new ManualResetEvent(false);
...
private void Run()
{
...
this.mre.Set(); // we completed our task
}
public void Wait();
{
this.mre.WaitOne();
}
然后你的代码调用b.test2()：
b.test2(); b.Wait();
