Opening files in java

[robby14]

Hi,
I am developing an applicaiton which I would need to run on windows, mac and on various other OSs. Would I need to do something to paths when for e.g. reading files eg. I have paths like //myFolder//myTxtFile.txt. Does this cater for everything?

Moreover I am opening files in this way: Process p = Runtime.getRuntime().exec("rundll32 url.dll,FileProtocolHandler "VirtualPortal.html");

But I think this works only on Windows. Is that right?
Could you please suggest other methods which would work on all OSs?

[Eranga]

Did you try those things in different OSs?

[Eranga]

Just to guide you,

Process p = Runtime.getRuntime().exec("rundll32 url.dll,FileProtocolHandler "VirtualPortal.html");

works on Windows only.

If you want to execute on the other OSs, like UNIX and so on try the following.

String[] browsers = { "firefox", "opera", "konqueror", "epiphany", 
                                        "mozilla", "netscape" };
                String browser = null;
                for (int count = 0; count < browsers.length && browser == null; count++) {
                    if (Runtime.getRuntime().exec(new String[]{"which", browsers[count]}).waitFor() == 0) {
                        browser = browsers[count];
                    }
                }
                if (browser == null) {
                    throw new Exception("Could not find web browser");
                }
                else {
                    Runtime.getRuntime().exec(new String[]{browser, file_url});
                }

[robby14]

hi,
thanks for the reply. I ve got a problem here if (Runtime.getRuntime().exec(new String[]{"which", browsers[count]}).waitFor() == 0)
what should I write instead of "which" please? or is it supposed to work as it is? It is giving me the following error:

java.io.IOException: Cannot run program "which": CreateProcess error=2, The system cannot find the file specified

[Eranga]

Can you show me your complete code. Seems you run this in windows in an odd way. Show your code.

[robby14]

my original code is just this. I have a method which creates an html page, named VirtualPortal.html and then after finishing tha I have the line bellow in order to open the web page into the default browser.

Process p = Runtime.getRuntime().exec("rundll32 url.dll,FileProtocolHandler "VirtualPortal.html");

Now when trying out your code, I just replaced the line above with

String[] browsers = { "firefox", "opera", "konqueror", "epiphany",
"mozilla", "netscape" };
String browser = null;
for (int count = 0; count < browsers.length && browser == null; count++) {
if (Runtime.getRuntime().exec(new String[]{"which", browsers[count]}).waitFor() == 0) {
browser = browsers[count];
}
}
if (browser == null) {
throw new Exception("Could not find web browser");
}
else {
Runtime.getRuntime().exec(new String[]{browser, "VirtualPortal.html"});
}

thanks

[JosAH]

'which' is a Unix/Linux command; you won't find it in a default Windows installation.

kind regards,

Jos

[Eranga]

'which' is a Unix/Linux command; you won't find it in a default Windows installation.

That's why I wonder. He just copy-paste the code and run it n Windows. I thouth he's just validate atleast on his code.

[Eranga]

@OP, validate when you execute the code. Because the complete code not compatible with a one OS, different segments with different OSs. You can do simple validation sa such.

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

            if (osName.startsWith("Windows")){
                Runtime.getRuntime().exec("rundll32 url.dll,FileProtocolHandler " 
                        + url);
            }
            else{
                String[] browsers = { "firefox", "opera", "konqueror", "epiphany", 
                                        "mozilla", "netscape" };
                String browser = null;
                for (int count = 0; count < browsers.length && browser == null; count++) {
                    if (Runtime.getRuntime().exec(new String[]{"which", browsers[count]}).waitFor() == 0) {
                        browser = browsers[count];
                    }
                }
                if (browser == null) {
                    throw new Exception("Could not find web browser");
                }
                else {
                    Runtime.getRuntime().exec(new String[]{browser, url});
                }
            }

[toadaly]

When you use Runtime.exec, you are outside the protective cover of portability you usually have from Java. There is no alternative to writing code to deal with every quirk of every OS when you do this.

If the web pages you're trying to display are fairly simple (just text and images, no flash, no javascript, etc.), then as an alternative to trying to bring up a browser, you could use a JEditorPane

[JosAH]

When you use Runtime.exec, you are outside the protective cover of portability you usually have from Java. There is no alternative to writing code to deal with every quirk of every OS when you do this.

If the web pages you're trying to display are fairly simple (just text and images, no flash, no javascript, etc.), then as an alternative to trying to bring up a browser, you could use a JEditorPane

Or, (even better imho) is using the Desktop class and let it figure out what default browser is installed on your system and be done with it.

kind regards,

Jos

[Eranga]

I agreed. But the way I use, deals the relevant DLLs and so on much use of me.