How to quickly find out who files are occupied in Win7

How to delete the files that are being used under Windows7?
How to know who is using a file under Windows7?
How do I find out who is holding a registry key? Don't let me change?
Please don't worry about recommending third-party software first. I can make my own decisions on the new site of Windows7. Let's look down--
When deleting files or folders, especially Temp temporary When you are in a folder, you may encounter the following error message [File is in use] or [Operation cannot be completed because the file is already open in XXX]. (Note: XXX stands for the program it opens.)

To successfully delete these files, first find out which processes called them and then close the related applications. Compared to previous operating systems, Windows 7's "files are being improved using the " dialog box, which usually lists what program is calling the file (shown in red in the figure above).
However, in many cases, the system still cannot list all the programs that call the files, so the files cannot be deleted smoothly. At this time, Windows 7 "Resource Monitor"--a little-named, yet practical tool--has worked.
Workaround:
Open the resource monitor. In the Start Search box, type "Resource Monitor" and press Enter to open it.

If you are prompted for an administrator password or for confirmation, type the password or provide confirmation.

In the "Resource Monitor" dialog, switch to the "CPU" tab. Click the small arrow to the right of the "associated handle" column to expand it. Enter the file name in the search field (if the file name is longer, enter a partial file name), and then press the Enter key. Now, all the files related to the file are listed in the "Image" column.

The process of calling the file is selected, right click the mouse, click “ end process & rdquo;.

It is now possible to delete related files/folders smoothly.
Small Tip: Using the associated handle search, we can also query the process corresponding to the registry key! ^^

(For reference only, not detailed)
PS:
Windows Vista, Windows XP systems do not have their own resource monitors, and similar queries are not possible. Instead, you can download a gadget, Process Explorer, to use when needed.