最近碰到一个窗口close（）后资源无法释放的问题，找了很久才发现原来时存在交叉引用，虽然close（）但是该form的对象依然被其他对象所引用，所以垃圾收集器并不能回收该form所占的资源。
| 1 | public class DeviceManager : IDeviceMonitorStatusNotify |
| 2 | { |
| 3 | public IDeviceManagerNotify deviceManagerNotify; |
| 4 | public DeviceManager(IDeviceManagerNotify notify) |
| 5 | { |
| 6 | deviceManagerNotify = notify; |
| 7 | } |
| 8 | |
| 9 | public void ReleaseAll() |
| 10 | { |
| 11 | //do some release resource |
| 12 | } |
| 13 | } |
| 14 | |
| 15 | public MainForm() |
| 16 | { |
| 17 | deviceManager = new DeviceManager(this); |
| 18 | private void ExitMainForm_Click(object sender, EventArgs e) |
| 19 | { |
| 20 | deviceManager .ReleaseAll(); |
| 21 | this.Close(); |
| 22 | } |
| 23 | } |
| 24 |
当MainForm 执行 this.Close()后 MainForm 和DeviceManager 所占的资源并不会被释放，因为MainForm 对象被DeviceManager 所引用、
DeviceManager 对象被MainForm 所引用，形成了交叉引用 ，虽然执行Close方法但是并不能释放资源，垃圾收集器并不会执行资源收集。
一个form关闭之前应该该对象是否被其他对象所引用，如果被引用则先将该对象的引用置为null，然后再close()才能释放该form所占的资源。
| 1 | public class DeviceManager : IDeviceMonitorStatusNotify |
| 2 | { |
| 3 | public IDeviceManagerNotify deviceManagerNotify; |
| 4 | public DeviceManager(IDeviceManagerNotify notify) |
| 5 | { |
| 6 | deviceManagerNotify = notify; |
| 7 | } |
| 8 | |
| 9 | public void ReleaseAll() |
| 10 | { |
| 11 | //do some release resource |
| 12 | //将对MainForm 的引用置为null |
| 13 | deviceManagerNotify = null; |
| 14 | } |
| 15 | } |
| 16 | |
| 17 | |
| 18 | public MainForm() |
| 19 | { |
| 20 | |
| 21 | deviceManager = new DeviceManager(this); |
| 22 | private void ExitMainForm_Click(object sender, EventArgs e) |
| 23 | { |
| 24 | deviceManager.ReleaseAll(); |
| 25 | //将对DeviceManager 的引用置为null |
| 26 | LocalManagers._Instance.DeviceManager = null; |
| 27 | //没有交叉引用，close后资源可以被垃圾收集器回收 |
| 28 | this.Close(); |
| 29 | } |
| 30 | } |
| 31 |