来自:https://www.cnblogs.com/had37210/p/8057042.html
主要是 Task 的降级:
1.net4.5.2 引入了 async/await 关键字. 这个其实国外大神已经有源码放出来了,我们把代码直接引入cefsharp 这个工程. 就可以直接在4.0里使用 async/await;
2.net4.5 对task api 做了扩展, 我们只需要在.net4.0实现一下对应的api.就可以了.
3. 源码里面用了很多4.5才有的GetTypeInfo 扩展方法错误. 它返回的类型是typeinfo,不用管它,把GetTypeInfo 删掉. 直接Type 调用就可以了.
4. 对Task静态方法的扩展,需要修改一下,静态方法的调用方式.
以上是要点.下面贴源码:
本段源码是对:async/await的支持:
namespace System.Threading.Tasks { public static class TaskEx { public static TaskAwaiter GetAwaiter(this Task task) { return new TaskAwaiter(task); } public static TaskAwaiterGetAwaiter (this Task task) { return new TaskAwaiter (task); } } public struct TaskAwaiter : INotifyCompletion { readonly Task task; internal TaskAwaiter(Task task) { this.task = task; } internal static TaskScheduler TaskScheduler { get { if (SynchronizationContext.Current == null) return TaskScheduler.Default; else return TaskScheduler.FromCurrentSynchronizationContext(); } } public bool IsCompleted { get { return task.IsCompleted; } } public void OnCompleted(Action continuation) { this.task.ContinueWith( delegate (Task task) { continuation(); }, TaskAwaiter.TaskScheduler); } public void GetResult() { try { task.Wait(); } catch (AggregateException ex) { throw ex.InnerExceptions[0]; } } } public struct TaskAwaiter : INotifyCompletion { readonly Task task; internal TaskAwaiter(Task task) { this.task = task; } public bool IsCompleted { get { return task.IsCompleted; } } public void OnCompleted(Action continuation) { this.task.ContinueWith( delegate (Task task) { continuation(); }, TaskAwaiter.TaskScheduler); } public T GetResult() { try { return task.Result; } catch (AggregateException ex) { throw ex.InnerExceptions[0]; } } } } namespace System.Runtime.CompilerServices { public interface INotifyCompletion { void OnCompleted(Action continuation); } public interface ICriticalNotifyCompletion : INotifyCompletion { [SecurityCritical] void UnsafeOnCompleted(Action continuation); } public interface IAsyncStateMachine { void MoveNext(); void SetStateMachine(IAsyncStateMachine stateMachine); } public struct AsyncVoidMethodBuilder { public static AsyncVoidMethodBuilder Create() { return new AsyncVoidMethodBuilder(); } public void SetException(Exception exception) { throw exception; } public void SetResult() { } public void SetStateMachine(IAsyncStateMachine stateMachine) { // Should not get called as we don't implement the optimization that this method is used for. throw new NotImplementedException(); } public void Start (ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine { stateMachine.MoveNext(); } public void AwaitOnCompleted (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : INotifyCompletion where TStateMachine : IAsyncStateMachine { awaiter.OnCompleted(stateMachine.MoveNext); } public void AwaitUnsafeOnCompleted (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : ICriticalNotifyCompletion where TStateMachine : IAsyncStateMachine { awaiter.OnCompleted(stateMachine.MoveNext); } } public struct AsyncTaskMethodBuilder { TaskCompletionSource<object> tcs; public Task Task { get { return tcs.Task; } } public static AsyncTaskMethodBuilder Create() { AsyncTaskMethodBuilder b; b.tcs = new TaskCompletionSource<object>(); return b; } public void Start (ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine { stateMachine.MoveNext(); } public void SetStateMachine(IAsyncStateMachine stateMachine) { // Should not get called as we don't implement the optimization that this method is used for. throw new NotImplementedException(); } public void AwaitOnCompleted (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : INotifyCompletion where TStateMachine : IAsyncStateMachine { awaiter.OnCompleted(stateMachine.MoveNext); } public void AwaitUnsafeOnCompleted (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : ICriticalNotifyCompletion where TStateMachine : IAsyncStateMachine { awaiter.OnCompleted(stateMachine.MoveNext); } public void SetResult() { tcs.SetResult(null); } public void SetException(Exception exception) { tcs.SetException(exception); } } public struct AsyncTaskMethodBuilder { TaskCompletionSource tcs; public Task Task { get { return tcs.Task; } } public static AsyncTaskMethodBuilder Create() { AsyncTaskMethodBuilder b; b.tcs = new TaskCompletionSource (); return b; } public void Start (ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine { stateMachine.MoveNext(); } public void SetStateMachine(IAsyncStateMachine stateMachine) { // Should not get called as we don't implement the optimization that this method is used for. throw new NotImplementedException(); } public void AwaitOnCompleted (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : INotifyCompletion where TStateMachine : IAsyncStateMachine { awaiter.OnCompleted(stateMachine.MoveNext); } public void AwaitUnsafeOnCompleted (ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : ICriticalNotifyCompletion where TStateMachine : IAsyncStateMachine { AwaitOnCompleted(ref awaiter, ref stateMachine); } public void SetResult(T result) { tcs.SetResult(result); } public void SetException(Exception exception) { tcs.SetException(exception); } } }
这段是对 Task 的扩展
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading; using System.Threading.Tasks; namespace CefSharp { public class TaskEx { public static TaskFromResult (T t) { return Task.Factory.StartNew (() => t); } public static Task Run(Action action) { var tcs = new TaskCompletionSource<object>(); new Thread(() => { try { action(); tcs.SetResult(null); } catch (Exception ex) { tcs.SetException(ex); } }) { IsBackground = true }.Start(); return tcs.Task; } public static Task Run (Func function) { var tcs = new TaskCompletionSource (); new Thread(() => { try { tcs.SetResult(function()); } catch (Exception ex) { tcs.SetException(ex); } }) { IsBackground = true }.Start(); return tcs.Task; } public static Task Delay(int milliseconds) { var tcs = new TaskCompletionSource<object>(); var timer = new System.Timers.Timer(milliseconds) { AutoReset = false }; timer.Elapsed += delegate { timer.Dispose(); tcs.SetResult(null); }; timer.Start(); return tcs.Task; } } }
把这些添加到代码里, 遇到 Task.Run 的时候,替换成 TaskEx.Run,遇到 Task.Delay 替换为TaskEx.Delay.
还有报 GetTypeInfo 这个错误的地方,删除就Ok了。