请问关于BeginInvoke的问题,马上揭贴

[ControlCoder39]

CreateCard crar = new CreateCard(rar.CreateTxt);
IAsyncResult ar = crar.BeginInvoke(num, new AsyncCallback(CreateRar), snum);
public static void CreateRar(IAsyncResult ar)
{

}

上面是委托的异步调用

怎么把参数传给回调函数啊,象我上面那样写对不对?snum是否能传给
CreateRar作为参数啊

那在CreateRar怎么接受这个参数呢

[ControlCoder39]

还有,回调函数能否写成private的?

[diandian82]

mark

[ControlCoder39]

顶

[ControlCoder39]

人呢

[xingyaohua]

顶

[真相重于对错]

CreateCard 是什么类型

[ControlCoder39]

private delegate void CreateCard(string num);

是我定义的委托啊

[真相重于对错]

还有,回调函数能否写成private的?
========================
关键看是谁在访问这个回调

[真相重于对错]

可以

[jimh]

用IAsyncResult.State来保存你需要的数据
IAsyncResult ar = crar.BeginInvoke(num, new AsyncCallback(CreateRar), snum);
ar.State = snum;

public static void CreateRar(IAsyncResult ar)
{
int num = (int)ar.State;
......
}

[AFatPig]

异步委托提供以异步方式调用同步方法的能力。当同步调用一个委托时，“Invoke”方法直接对当前线程调用目标方法。如果编译器支持异步委托，则它将生成“Invoke”方法以及“BeginInvoke”和“EndInvoke”方法。如果调用“BeginInvoke”方法，则公共语言运行库 (CLR) 将对请求进行排队并立即返回到调用方。将对来自线程池的线程调用该目标方法。提交请求的原始线程自由地继续与目标方法并行执行，该目标方法是对线程池线程运行的。如果在对“BeginInvoke”方法的调用中指定了回调方法，则当目标方法返回时将调用该回调方法。在回调方法中，“EndInvoke”方法获取返回值和所有输入/输出参数。如果在调用“BeginInvoke”时未指定任何回调方法，则可以从调用“BeginInvoke”的线程中调用“EndInvoke”。

要点
使用用户指定的委托签名，编译器应发出具有“Invoke”、“BeginInvoke”和“EndInvoke”方法的委托类。“BeginInvoke”和“EndInvoke”方法应被修饰为本机的。因为这些方法被标记为本机的，所以 CLR 在类加载时自动提供该实现。加载程序确保它们未被重写。

using System;
using System.Threading;
using System.Runtime.Remoting.Messaging;

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
// Create a class that factors a number.
public class PrimeFactorFinder
{
public static bool Factorize(
int number,
ref int primefactor1,
ref int primefactor2)
{
primefactor1 = 1;
primefactor2 = number;

// Factorize using a low-tech approach.
for (int i=2;i<number;i++)
{
if (0 == (number % i))
{
primefactor1 = i;
primefactor2 = number / i;
break;
}
}
if (1 == primefactor1 )
return false;
else
return true ;
}
}

// Create an asynchronous delegate that matches the Factorize method.
public delegate bool AsyncFactorCaller (
int number,
ref int primefactor1,
ref int primefactor2);

public class DemonstrateAsyncPattern
{
// The waiter object used to keep the main application thread
// from terminating before the callback method completes.
ManualResetEvent waiter;

// Define the method that receives a callback when the results are available.
public void FactorizedResults(IAsyncResult result)
{
int factor1=0;
int factor2=0;

// Extract the delegate from the
// System.Runtime.Remoting.Messaging.AsyncResult.
AsyncFactorCaller factorDelegate = (AsyncFactorCaller)((AsyncResult)result).AsyncDelegate;
int number = (int) result.AsyncState;
// Obtain the result.
bool answer = factorDelegate.EndInvoke(ref factor1, ref factor2, result);
// Output the results.
Console.WriteLine("On CallBack: Factors of {0} : {1} {2} - {3}",
number, factor1, factor2, answer);
waiter.Set();
}

// The following method demonstrates the asynchronous pattern using a callback method.
public void FactorizeNumberUsingCallback()
{
AsyncFactorCaller factorDelegate = new AsyncFactorCaller (PrimeFactorFinder.Factorize);
int number = 1000589023;
int temp=0;
// Waiter will keep the main application thread from
// ending before the callback completes because
// the main thread blocks until the waiter is signaled
// in the callback.
waiter = new ManualResetEvent(false);

// Define the AsyncCallback delegate.
AsyncCallback callBack = new AsyncCallback(this.FactorizedResults);

// Asynchronously invoke the Factorize method.
IAsyncResult result = factorDelegate.BeginInvoke(
number,
ref temp,
ref temp,
callBack,
number);

// Do some other useful work while
// waiting for the asynchronous operation to complete.

// When no more work can be done, wait.
waiter.WaitOne();
}

// The following method demonstrates the asynchronous pattern
// using a BeginInvoke, followed by waiting with a time-out.
public void FactorizeNumberAndWait()
{
AsyncFactorCaller factorDelegate = new AsyncFactorCaller (PrimeFactorFinder.Factorize);

int number = 1000589023;
int temp=0;

// Asynchronously invoke the Factorize method.
IAsyncResult result = factorDelegate.BeginInvoke(
number,
ref temp,
ref temp,
null,
null);

while (!result.IsCompleted)
{
// Do any work you can do before waiting.
result.AsyncWaitHandle.WaitOne(10000, false);
}
// The asynchronous operation has completed.
int factor1=0;
int factor2=0;

// Obtain the result.
bool answer = factorDelegate.EndInvoke(ref factor1, ref factor2, result);

// Output the results.
Console.WriteLine("Sequential : Factors of {0} : {1} {2} - {3}",
number, factor1, factor2, answer);
}

public static void Main()
{
DemonstrateAsyncPattern demonstrator = new DemonstrateAsyncPattern();
demonstrator.FactorizeNumberUsingCallback();
demonstrator.FactorizeNumberAndWait();
}
}
}

[ControlCoder39]

IAsyncResult ar = crar.BeginInvoke(num, new AsyncCallback(CreateRar), snum);


这里的第三个参数是什么啊?

如果回调函数都是在本类里,我可以写成private类型的吗?

[ControlCoder39]

还有,如果我想怎么获得异步调用的状态呢?

就是说当前执行到哪一步了

[ControlCoder39]

顶