Cross-platform way to open a file using Java 1.5

Question

I'm using Java 1.5 and I'd like to launch the associated application to open the file. I know that Java 1.6 introduced the Desktop API, but I need a solution for Java 1.5.

So far I found a way to do it in Windows:

Runtime.getRuntime().exec(new String[]{ "rundll32", 
                          "url.dll,FileProtocolHandler", fileName });

Is there a cross-platform way to do it? Or at least a similar solution for Linux?

Answer 1

+1 for this answer

Additionally I would suggest the following implementation using polymorphism:

This way you can add new platform easier by reducing coupling among classes.

The Client code:

 Desktop desktop = Desktop.getDesktop();

 desktop.open( aFile );
 desktop.imaginaryAction( aFile );

The Desktop impl:

package your.pack.name;

import java.io.File;

public class Desktop{

    // hide the constructor.
    Desktop(){}

    // Created the appropriate instance
    public static Desktop getDesktop(){

        String os = System.getProperty("os.name").toLowerCase();

        Desktop desktop = new Desktop();
         // This uf/elseif/else code is used only once: here
        if ( os.indexOf("windows") != -1 || os.indexOf("nt") != -1){

            desktop = new WindowsDesktop();

        } else if ( os.equals("windows 95") || os.equals("windows 98") ){

            desktop = new Windows9xDesktop();

        } else if ( os.indexOf("mac") != -1 ) {

            desktop = new OSXDesktop();

        } else if ( os.indexOf("linux") != -1 && isGnome() ) {

            desktop = new GnomeDesktop();

        } else if ( os.indexOf("linux") != -1 && isKde() ) {

            desktop = new KdeDesktop();

        } else {
            throw new UnsupportedOperationException(String.format("The platform %s is not supported ",os) );
        }
        return desktop;
    }

    // default implementation :( 
    public void open( File file ){
        throw new UnsupportedOperationException();
    }

    // default implementation :( 
    public void imaginaryAction( File file  ){
        throw new UnsupportedOperationException();
    }
}

// One subclass per platform below:
// Each one knows how to handle its own platform   


class GnomeDesktop extends Desktop{

    public void open( File file ){
        // Runtime.getRuntime().exec: execute gnome-open <file>
    }

    public void imaginaryAction( File file ){
        // Runtime.getRuntime().exec:gnome-something-else <file>
    }

}
class KdeDesktop extends Desktop{

    public void open( File file ){
        // Runtime.getRuntime().exec: kfmclient exec <file>
    }

    public void imaginaryAction( File file ){
        // Runtime.getRuntime().exec: kfm-imaginary.sh  <file>
    }
}
class OSXDesktop extends Desktop{

    public void open( File file ){
        // Runtime.getRuntime().exec: open <file>
    }

    public void imaginaryAction( File file ){
        // Runtime.getRuntime().exec: wow!! <file>
    }
}
class WindowsDesktop extends Desktop{

    public void open( File file ){
        // Runtime.getRuntime().exec: cmd /c start <file>
    }

    public void imaginaryAction( File file ){
        // Runtime.getRuntime().exec: ipconfig /relese /c/d/e
    }
}
class Windows9xDesktop extends Desktop{

    public void open( File file ){
        //Runtime.getRuntime().exec: command.com /C start <file>
    }

    public void imaginaryAction( File file){
       //Runtime.getRuntime().exec: command.com /C otherCommandHere <file>
    }
}

This is only an example, in real life is not worth to create a new class only to parametrize a value ( the command string %s ) But let's do imagine that each method performs another steps in platform specific way.

Doing this kind of approach, may remove unneeded if/elseif/else constructs that with time may introduce bugs ( if there are 6 of these in the code and a change is neede, you may forget to update one of them, or by copy/pasting you may forget to change the command to execute)