正确实现IDisposable

在我的课程中，我实现IDisposable的方式如下：

public class User : IDisposable
{
    public int id { get; protected set; }
    public string name { get; protected set; }
    public string pass { get; protected set; }

    public User(int UserID)
    {
        id = UserID;
    }
    public User(string Username, string Password)
    {
        name = Username;
        pass = Password;
    }

    // Other functions go here...

    public void Dispose()
    {
        // Clear all property values that maybe have been set
        // when the class was instantiated
        id = 0;
        name = String.Empty;
        pass = String.Empty;
    }
}

在VS2012中，我的代码分析说要正确实现IDisposable，但我不确定在这里做错了什么。
确切的文本如下：

CA1063正确实施IDisposable可在“用户”上提供Dispose（bool）的可重写实现，或将类型标记为密封。调用Dispose（false）仅应清除本机资源。调用Dispose（true）应该同时清除托管资源和本机资源。stman User.cs 10

供参考：CA1063：正确实现IDisposable

我已经通读了此页面，但是恐怕我不太了解在这里需要做什么。

如果任何人都可以用更深刻的解释来解释问题是什么和/或应该如何实现IDisposable，那将真的有帮助！

这是正确的实现，尽管在发布的代码中我看不到需要处理的任何内容。您仅需要在以下情况下实施IDisposable：

1. 您拥有不受管理的资源
2. 您要坚持引用那些本身就是一次性的东西。

您发布的代码中的任何内容都不需要处理。

public class User : IDisposable
{
    public int id { get; protected set; }
    public string name { get; protected set; }
    public string pass { get; protected set; }

    public User(int userID)
    {
        id = userID;
    }
    public User(string Username, string Password)
    {
        name = Username;
        pass = Password;
    }

    // Other functions go here...

    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    protected virtual void Dispose(bool disposing)
    {
        if (disposing) 
        {
            // free managed resources
        }
        // free native resources if there are any.
    }
}

首先，您不需要“清理” strings和ints-垃圾收集器将自动处理它们。唯一需要清除的Dispose是实现的非托管资源或托管资源IDisposable。

但是，假设这只是一个学习活动，建议的实现方式IDisposable是添加一个“安全陷阱”，以确保不会两次处置任何资源：

public void Dispose()
{
    Dispose(true);

    // Use SupressFinalize in case a subclass 
    // of this type implements a finalizer.
    GC.SuppressFinalize(this);   
}
protected virtual void Dispose(bool disposing)
{
    if (!_disposed)
    {
        if (disposing) 
        {
            // Clear all property values that maybe have been set
            // when the class was instantiated
            id = 0;
            name = String.Empty;
            pass = String.Empty;
        }

        // Indicate that the instance has been disposed.
        _disposed = true;   
    }
}

以下示例显示了实现IDisposable接口的一般最佳实践。参考

请记住，仅当您的类中具有非托管资源时才需要析构函数（finalizer）。而且，如果添加了析构函数，则应在Dispose中抑制Finalization，否则它将导致您的对象在内存中停留两个垃圾回收周期（注意：阅读Finalization的工作原理）。下面的例子详细说明了上面。

public class DisposeExample
{
    // A base class that implements IDisposable. 
    // By implementing IDisposable, you are announcing that 
    // instances of this type allocate scarce resources. 
    public class MyResource: IDisposable
    {
        // Pointer to an external unmanaged resource. 
        private IntPtr handle;
        // Other managed resource this class uses. 
        private Component component = new Component();
        // Track whether Dispose has been called. 
        private bool disposed = false;

        // The class constructor. 
        public MyResource(IntPtr handle)
        {
            this.handle = handle;
        }

        // Implement IDisposable. 
        // Do not make this method virtual. 
        // A derived class should not be able to override this method. 
        public void Dispose()
        {
            Dispose(true);
            // This object will be cleaned up by the Dispose method. 
            // Therefore, you should call GC.SupressFinalize to 
            // take this object off the finalization queue 
            // and prevent finalization code for this object 
            // from executing a second time.
            GC.SuppressFinalize(this);
        }

        // Dispose(bool disposing) executes in two distinct scenarios. 
        // If disposing equals true, the method has been called directly 
        // or indirectly by a user's code. Managed and unmanaged resources 
        // can be disposed. 
        // If disposing equals false, the method has been called by the 
        // runtime from inside the finalizer and you should not reference 
        // other objects. Only unmanaged resources can be disposed. 
        protected virtual void Dispose(bool disposing)
        {
            // Check to see if Dispose has already been called. 
            if(!this.disposed)
            {
                // If disposing equals true, dispose all managed 
                // and unmanaged resources. 
                if(disposing)
                {
                    // Dispose managed resources.
                    component.Dispose();
                }

                // Call the appropriate methods to clean up 
                // unmanaged resources here. 
                // If disposing is false, 
                // only the following code is executed.
                CloseHandle(handle);
                handle = IntPtr.Zero;

                // Note disposing has been done.
                disposed = true;

            }
        }

        // Use interop to call the method necessary 
        // to clean up the unmanaged resource.
        [System.Runtime.InteropServices.DllImport("Kernel32")]
        private extern static Boolean CloseHandle(IntPtr handle);

        // Use C# destructor syntax for finalization code. 
        // This destructor will run only if the Dispose method 
        // does not get called. 
        // It gives your base class the opportunity to finalize. 
        // Do not provide destructors in types derived from this class.
        ~MyResource()
        {
            // Do not re-create Dispose clean-up code here. 
            // Calling Dispose(false) is optimal in terms of 
            // readability and maintainability.
            Dispose(false);
        }
    }
    public static void Main()
    {
        // Insert code here to create 
        // and use the MyResource object.
    }
}

IDisposable存在的目的是为您提供一种清理非托管资源的方法，这些资源不会被垃圾收集器自动清理。

您正在“清理”的所有资源都是托管资源，因此您的Dispose方法无法完成任何工作。您的课程根本不应该实现IDisposable。垃圾收集器将自行处理所有这些字段。

您需要像这样使用一次性模式：

private bool _disposed = false;

protected virtual void Dispose(bool disposing)
{
    if (!_disposed)
    {
        if (disposing)
        {
            // Dispose any managed objects
            // ...
        }

        // Now disposed of any unmanaged objects
        // ...

        _disposed = true;
    }
}

public void Dispose()
{
    Dispose(true);
    GC.SuppressFinalize(this);  
}

// Destructor
~YourClassName()
{
    Dispose(false);
}

您不需要做您的User课程，IDisposable因为该课程不会获取任何非托管资源（文件，数据库连接等）。通常，我们将类标记为 IDisposable具有至少一个IDisposable字段或/和属性。在实施时IDisposable，最好根据微软的典型方案：

public class User: IDisposable {
  ...
  protected virtual void Dispose(Boolean disposing) {
    if (disposing) {
      // There's no need to set zero empty values to fields 
      // id = 0;
      // name = String.Empty;
      // pass = String.Empty;

      //TODO: free your true resources here (usually IDisposable fields)
    }
  }

  public void Dispose() {
    Dispose(true);

    GC.SuppressFinalize(this);
  } 
}

每当需要确定性（已确认）垃圾收集时，isdisposable便是一种实现。

class Users : IDisposable
    {
        ~Users()
        {
            Dispose(false);
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
            // This method will remove current object from garbage collector's queue 
            // and stop calling finilize method twice 
        }    

        public void Dispose(bool disposer)
        {
            if (disposer)
            {
                // dispose the managed objects
            }
            // dispose the unmanaged objects
        }
    }

在创建和使用Users类时，请使用“ using”块，以避免显式调用dispose方法：

using (Users _user = new Users())
            {
                // do user related work
            }

在using块末尾创建的Users对象将通过隐式调用dispose方法进行处置。

我看到了很多Microsoft Dispose模式的示例，这实际上是一种反模式。正如许多人指出的那样，问题中的代码根本不需要IDisposable。但是，如果您打算在哪里实现它，请不要使用Microsoft模式。更好的答案是遵循本文中的建议：

https://www.codeproject.com/Articles/29534/IDisposable-What-Your-Mother-Never-Told-You-About

唯一可能有用的其他事情是抑制该代码分析警告... https://docs.microsoft.com/zh-cn/visualstudio/code-quality/in-source-suppression-overview?view=vs- 2017年