今天在群里，有人问
有几个void返回值的方法，但是我想让这几个方法有执行顺序，要怎么处理，ABCD 四个方法，依次执行，但是这几个方法都是无返回值的
这个问题其实很简单，如果方法是同步方法，直接四个方法连续写就好了，比如：
static void Main()
{
A();
B();
C();
D();
}
但是如果方法里面包含了耗时操作（数据提交或者文件操作等），那么四个这样写就有问题了，执行顺序就错掉了，我们需要利用callback函数来进行操作，但是本着能不动原方法就不动的理念，我们使用Task的OnCompleted事件（.net framework中可以使用BeginInvoke(callback,null)）来做处理
由于是没有返回值的方法，我们使用
例如
static void Main()
{
Action action1 = () => {
Thread.Sleep(1000);
Console.WriteLine("action1");
};
Action action2 = () => {
Thread.Sleep(2000);
Console.WriteLine("action2");
};
Action action3 = () => {
Thread.Sleep(3000);
Console.WriteLine("action3");
};
Action action4 = () => {
Thread.Sleep(3000);
Console.WriteLine("action4");
};
Stack st = new Stack();
st.Push(action2);
st.Push(action3);
st.Push(action4);
void MyAsynCallback()
{
if (st.Count > 0)
{
var action = (Action)st.Pop();
Task.Run(action).GetAwaiter().OnCompleted(() =>
{
MyAsynCallback();
});
}
}
Task.Run(action1).GetAwaiter().OnCompleted(() =>
{
MyAsynCallback();
});
Console.ReadLine();
//Stack的Pop是先进后出，输出顺序action1 action4 action3 action2
}
我们可以将Stack改成其他的，比如List、Queue等，自行判断是否需要手动弹出action即可
static void Main()
{
Action action1 = () => {
Thread.Sleep(1000);
Console.WriteLine("action1");
};
Action action2 = () => {
Thread.Sleep(2000);
Console.WriteLine("action2");
};
Action action3 = () => {
Thread.Sleep(3000);
Console.WriteLine("action3");
};
Action action4 = () => {
Thread.Sleep(3000);
Console.WriteLine("action4");
};
Stack st = new Stack();
st.Push(action2);
st.Push(action3);
st.Push(action4);
void MyAsynCallback(IAsyncResult async)
{
if (st.Count > 0)
{
var action = (Action)st.Pop();
action.BeginInvoke(new AsyncCallback(MyAsynCallback),null);
}
}
action1.BeginInvoke(new AsyncCallback(MyAsynCallback), null);
Console.ReadLine();
//Stack的Pop是先进后出，输出顺序action1 action4 action3 action2
}
由于是没有返回值的方法，我们使用
例如
static void Main()
{
Func<int> func1 = () => {
Thread.Sleep(1000);
Console.WriteLine("func1");
return 1;
};
Func<int> func2 = () => {
Thread.Sleep(2000);
Console.WriteLine("func2");
return 1;
};
Func<int> func3 = () => {
Thread.Sleep(3000);
Console.WriteLine("func3");
return 0;
};
Func<int> func4 = () => {
Thread.Sleep(3000);
Console.WriteLine("func4");
return 1;
};
Stack st = new Stack();
st.Push(func2);
st.Push(func3);
st.Push(func4);
void MyAsynCallback(int result)
{
if (st.Count > 0 && result > 0)
{
var action = (Func<int>)st.Pop();
var task1 = Task.Run(action);
task1.GetAwaiter().OnCompleted(() =>
{
MyAsynCallback(task1.Result);
});
}
}
var task = Task.Run(func1);
task.GetAwaiter().OnCompleted(() =>
{
MyAsynCallback(task.Result);
});
Console.ReadLine();
//Stack的Pop是先进后出，输出顺序func1 func4 func3 func2
}
</int></int></int></int></int>
delegate int dele_func(int a);
static void Main()
{
Func<int> func1 = () => {
Thread.Sleep(1000);
Console.WriteLine("func1");
return 1;
};
Func<int> func2 = () => {
Thread.Sleep(2000);
Console.WriteLine("func2");
return 1;
};
Func<int> func3 = () => {
Thread.Sleep(3000);
Console.WriteLine("func3");
return 1;
};
Func<int> func4 = () => {
Thread.Sleep(3000);
Console.WriteLine("func4");
return 1;
};
Stack st = new Stack();
st.Push(func2);
st.Push(func3);
st.Push(func4);
void MyAsynCallback(IAsyncResult async)
{
dele_func dele_Func2 = (dele_func)async.AsyncState;
int result = dele_Func2.EndInvoke(async);
if (st.Count > 0 && result > 0)
{
var action = (Func<int>)st.Pop();
dele_func dele_Func1 = new dele_func((int a) => { return action.Invoke(); });
IAsyncResult asyncResult1 = dele_Func1.BeginInvoke(0, new AsyncCallback(MyAsynCallback), dele_Func1);
}
}
dele_func dele_Func = new dele_func((int a) => { return func1.Invoke(); });
IAsyncResult asyncResult = dele_Func.BeginInvoke(0, new AsyncCallback(MyAsynCallback), dele_Func);
Console.ReadLine();
//Stack的Pop是先进后出，输出顺序func1 func4 func3 func2
}
</int></int></int></int></int>
如有问题，欢迎指正
Original: https://www.cnblogs.com/spatxos/p/15892850.html
Author: spatxos
Title: ABCD四个顺序执行方法，拓展性延申
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