How to get the icon for a file extension or filetype without creating a temp file?

问题

I list some filenames with their icons (like the ones in the Windows Explorer) in a JTable. I know the two ways to get the icon if I have a File object from the local file system:

javax.swing.filechooser.FileSystemView.getFileSystemView().getSystemIcon( file )

for a 16x16 icon or for a bigger one:

sun.awt.shell.ShellFolder.getShellFolder( file ).getIcon( true ) )

Since my files are stored in a database, I don't have the File object. My workaround is to create a temp file with the specific filename extension, use one of the two methods above and cache the icon to display it in a CellRenderer.

I searched for a solution without temporary files and found two I don't like either:

• org.eclipse.swt.program.Program.findProgram(String extension).getImageData(), but I don't want to use SWT
• org.jdesktop.jdic.icons.IconService from the Incubator of the JDIC project. The last changes on the IconService are 6 years ago, on JDIC 2 years ago and I can't find a downloadable jar.

Is there another solution?

回答1:

Looks like you already discovered the way to do it, unless you want to dive into native libraries etc.

FileSystemView uses Win32ShellFolder internally so they are basically the same.

I also dug up the Source for org.eclipse.swt.program.Program and with it org.eclipse.swt.internal.win32.OS. The OS class then uses a native call for the Icon. At this point unless you really really cannot create a Temp File i would not go down that path.

For JDIC i only found http://kickjava.com/src/org/jdesktop/jdic/tray/internal/impl/WinTrayIconService.java.htm with a little bit of digging(may not be related but does icony things :D). Also calls native.

回答2:

Do you really need the temporary file to use the first option? A File does not have to denote a file that actually exists...

来源：https://stackoverflow.com/questions/8521294/how-to-get-the-icon-for-a-file-extension-or-filetype-without-creating-a-temp-fil