Swing Hacks

412

|

Chapter 11, Native Integration and Packaging

#80 Open Files, Directories, and URLs on Mac OS X

HACK

open has a simple syntax: open filename. By calling it from within your pro-

gram, you can open any file with its default application.

open will start

launching the viewer automatically and return control to your program

immediately. As in Microsoft Windows, you can call the program using

Runtime.exec( )

:

public static void main(String[] args) throws Exception {

Runtime rt = Runtime.getRuntime( );

rt.exec("open notes.txt");

}

This program will open a file in the current directory (notes.txt), in the

default viewer for text files, usually

TextEdit. You can also specify an abso-

lute path for the file:

rt.exec("open /Users/josh/Desktop/notes.txt");

If you pass a directory instead of a file, then OS X will open that directory in

a new Finder window. This can be useful for showing the location of a

recently downloaded file or demonstrating where to install new software:

// open the current working directory

rt.exec("open .");

// open the applications directory

rt.exec("open /Applications");

Finally, you can open any web page using the user’s default web browser

(probably Safari) by calling

open with a URL:

// open Yahoo! in the user's web browser

rt.exec("open http://www.yahoo.com/");

Handle Spaces

Some filepaths may contain spaces. When you run open from the command

line you can escape these spaces using quotes like this:

open 'Current Notes.txt'

Unfortunately, quotes won’t work when you call open from a program

because the quotes are actually interpreted by the user’s command-line

shell, not

open itself. When you call open directly from a program, you are

bypassing the shell and lose quote interpolation. The solution is to break the

command line into an array of arguments manually. That way

open knows

what is a space and what is the gap between arguments:

Runtime rt = Runtime.getRuntime( );

String[] cmd = {"open", "Current Notes.txt"};

rt.exec(cmd);

Now, you might wonder why open needs to distinguish between argument

gaps and real spaces when it takes only one argument to begin with.

open