从应用程序安装Java Web Start

Question

I have a simple Java program that uses:

Runtime.getRuntime().exec("/usr/bin/javaws", [path for JNLP file]) 

to open a JNLP file using java web start.

However, I need to deal with the scenario of javaws not being installed. So I need to check to see if it is installed and, if it's not, install it. Any idea how to do either of those (or both)?

Answer 1

Firstly, you're assuming that the path to javaws is /usr/bin/javaws , which may not be the case.

If it were that simple, then you can check if the file exists:

File javawsFile = new File("/usr/bin/javaws");
if (! javawsFile.exists()) {
    System.out.println("javaws not installed");
} 

Having said that, java does not have to be installed to any particular location. Thus you can't assume it's in /usr/bin/ . Many people will download the java binary zip and simply decompress it to their choice of location, and set the environment variable JAVA_HOME .

Now, you could go down the path of resolving the JAVA_HOME variable - but even then it'll only tell you if javaws is installed - or not.

If javaws is not installed, there is not really a way to install it - other than prompting the user to go off to the java website and download it.

The path you give is in *nix style. In this case it would require root access to install new applications - which isn't something you can simply manufacture.

Even if your user was already running your application as root, I would still be wary of this. It's not your responsibility to install software on your users' machines.