我正在做的是创建一个对象（A），它包含对另一个对象（B）的引用。我的代码的UI部分将这些对象（A）保存在BindingList中，该BindingList用作DevExpress网格视图的数据源。控制器通过事件将新创建的对象（A）发送到UI。控制器还有一个更新引用对象（B）的线程。抛出的异常来自DevExpress GridView并读取“检测到跨线程操作。要抑制此异常，请设置DevExpress.Data.CurrencyDataController.DisableThreadingProblemsDetection = true”。
现在我不想压制此异常，因为代码最终会在关键应用程序中结束。
那么如何在不引起问题的情况下跨线程更新引用对象？这是我的Test应用程序的代码。它在实际程序中基本相同。
更新 UI中的错误是由Nicholas Butler的答案修复的，但现在异常已经进入了Employee类。我已更新代码以反映更改。
这是我的代码
* UI *
public partial class Form1 : Form
{
private BindingList<IEmployee> empList;
EmployeeController controller;
private delegate void AddEmployeInvoke(IEmployee employee);
public Form1()
{
controller = new EmployeeController();
controller.onNewEmployee += new EmployeeController.NewEmployee(controller_onNewEmployee);
empList = new BindingList<IEmployee>();
InitializeComponent();
}
void controller_onNewEmployee(IEmployee emp)
{
AddEmployee(emp);
}
private void AddEmployee(IEmployee empl)
{
if (InvokeRequired)
{
this.Invoke(new AddEmployeInvoke(AddEmployee), new Object[] {empl});
}
else
{
empList.Add(empl);
}
}
private void Form1_Load(object sender, EventArgs e)
{
this.gridControl1.DataSource = empList;
this.gridControl1.RefreshDataSource();
controller.Start();
}
}
控制器：
class EmployeeController
{
List<IEmployee> emps;
Task empUpdater;
CancellationToken cancelToken;
CancellationTokenSource tokenSource;
Pay payScale1;
Pay payScale2;
public EmployeeController()
{
payScale1 = new Pay(12.00, 10.00);
payScale2 = new Pay(14.00, 11.00);
emps = new List<IEmployee>();
}
public void Start()
{
empUpdater = new Task(AddEmployee, cancelToken);
tokenSource = new CancellationTokenSource();
cancelToken = tokenSource.Token;
empUpdater.Start();
}
public bool Stop()
{
tokenSource.Cancel();
while (!empUpdater.IsCompleted)
{ }
return true;
}
private void AddEmployee()
{
IEmployee emp = new Employee("steve", ref payScale1);
ThrowEmployeeEvent(emp);
emps.Add(emp);
emp = new Employee("bob", ref payScale2);
ThrowEmployeeEvent(emp);
emps.Add(emp);
int x = 0;
while (!cancelToken.IsCancellationRequested)
{
emp = new Employee("Emp" + x, ref payScale1);
ThrowEmployeeEvent(emp);
x++;
emp = new Employee("Emp" + x, ref payScale2);
ThrowEmployeeEvent(emp);
Thread.Sleep(1000);
payScale2.UpdatePay(10.0);
payScale1.UpdatePay(11.0);
Thread.Sleep(5000);
}
}
private void ThrowEmployeeEvent(IEmployee emp)
{
if (onNewEmployee != null)
onNewEmployee(emp);
}
public delegate void NewEmployee(IEmployee emp);
public event NewEmployee onNewEmployee;
}
员工类:(此类中抛出异常）
class Employee : IEmployee
{
private string _name;
private double _salary;
private Pay _myPay;
public string Name
{
get { return _name; }
set { _name = value;
//if (PropertyChanged != null) this.PropertyChanged(this, new PropertyChangedEventArgs("Name"));
}
}
public double Salary
{
get { return _salary; }
}
int x = 1;
public Employee(string name, ref Pay pay)
{
_myPay = pay;
_myPay.PropertyChanged += new PropertyChangedEventHandler(_myPay_PropertyChanged);
_salary = _myPay.Salary;
Name = name;
}
void _myPay_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "Salary")
{
_salary = _myPay.Salary;
if (this.PropertyChanged != null)
// exception thrown on the line below
this.PropertyChanged(this, new PropertyChangedEventArgs("Salary"));
}
}
public void ChangeName()
{
Name = "Me " + x;
x++;
}
public event PropertyChangedEventHandler PropertyChanged;
}
员工界面：
interface IEmployee : INotifyPropertyChanged
{
string Name { get; set; }
double Salary { get;}
}
薪酬等级：
class Pay : INotifyPropertyChanged
{
private double _salary;
private double _bonus;
public double Salary { get { return _salary; } set { _salary = value; if(PropertyChanged != null) this.PropertyChanged(this, new PropertyChangedEventArgs("Salary"));} }
public double Bonus { get { return _bonus; } set { _bonus = value; if (PropertyChanged != null) this.PropertyChanged(this, new PropertyChangedEventArgs("Bonus")); } }
public Pay(double salary, double bonus)
{
Salary = salary;
Bonus = bonus;
}
public void UpdatePay(double salary)
{
Salary += salary;
if (onChange != null)
this.onChange();
}
public void UpdatePay(double salary, double bonus)
{
Salary += salary;
Bonus += bonus;
if (onChange != null)
this.onChange();
}
public delegate void Change();
public event Change onChange;
public event PropertyChangedEventHandler PropertyChanged;
}
我非常感谢任何帮助。
答案 0 :(得分：2)
问题是在非UI线程上触发了EmployeeController.onNewEmployee。使用基于事件的异步模式来引发特定（在本例中为UI）线程上的事件：http://msdn.microsoft.com/en-us/library/hkasytyf.aspx。
或者，您可以在每个事件处理程序中检查IsInvokeRequired，如果是这样，请使用.Invoke返回到UI线程..这样更麻烦，但在您的情况下可能更容易/更快地实现。
答案 1 :(得分：1)
即使empList.Add(empl);，您也在呼叫InvokeRequired == true。尝试：
private void AddEmployee(IEmployee empl)
{
if (InvokeRequired)
{
this.Invoke(new AddEmployeInvoke(AddEmployee), new Object[] {empl});
}
else
{
empList.Add(empl); //exception thrown here
}
}
您还需要在UI线程上引发INotifyPropertyChanged事件，但您没有用于调用Invoke的UI控件。这样做的简单方法是存储对主表单的引用并将其设为public static：
public partial class Form1 : Form
{
public static Control UI { get; private set; }
public Form1()
{
UI = this;
}
}
然后，您可以在应用中的任何位置使用Form1.UI.InvokeRequired和Form1.UI.Invoke。
我尝试一步一步，但如果您想要更正确的解决方案，可以将用户界面SynchronizationContext传递给控制器并使用其Post或Send方法：
public Form1()
{
controller = new EmployeeController( SynchronizationContext.Current );
...
class EmployeeController
{
private SynchronizationContext _SynchronizationContext = null;
public EmployeeController( SynchronizationContext sc )
{
_SynchronizationContext = sc;
...
然后你必须得到你的对象。要举办活动，您可以这样做：
var evt = this.PropertyChanged;
if ( evt != null ) sc.Send(
new SendOrPostCallback( state => evt( this, ...EventArgs... ) ),
null );