How to run Different commands from Java Code?

问题

I want to run different commands which can be executed on my command prompt or terminal through Java.

I did search few place but did not get appropriate reply.

I want to run a compiler which is set in the environment as VISAGE_HOME as well as run GRADLE so as to do all my build tasks.

I want to invoke all these commands from within Java Program.

Since it is a swing application I would like to invoke these commands on click of button or some other events.

My Problem is that I am not able to program this :( .

Neither do I know an API which would do this. I went through some sample codes but most of them have same kind of example codes of executing the shell commands or command prompt commands. None showed me to do the above stuff.

回答1:

Have a look at ProcessBuilder. The Process object it returns has a waitFor method so you can wait for the process to finish. Then you can start your next process.

For example

Process p = new ProcessBuilder("runYourCommand").start();
InputStream in = process.getInputStream();
InputStreamReader inr = new InputStreamReader(in);
BufferedReader br = new BufferedReader(inr);
String inputLine;
while ((inputLine = br.readLine()) != null) {
  System.out.println(inputLine);
}
p.waitFor();

Another interesting method on ProcessBuilder is environment(). This will return the environment variables that you can access. From the API docs

Map<String, String> env = pb.environment();  
env.put("VAR1", "myValue");

回答2:

Something like this:

String cmd = "gedit";

Runtime run = Runtime.getRuntime();

Process pr = run.exec(cmd);

回答3:

Firstly, ProcessBuilder is your friend...

You could have a look at;

• Getting started with Java’s ProcessBuilder (Linux focus)
• Using ProcessBuilder to Make System Calls
• Run processbuilder and get in and output
• ProcessBuilder and how redirecting input and output from operating system's processes
• Executing Operating System Commands from Java

Secondly, You will need to use System.getenv to find the value of the specified environment variable and substitute it yourself.

nb: Thanks to Guillaume Polet for pointing out that the Process will automatically include the path environment variable to find commands.

Also, remember, DO NOT EXECUTE ANY BLOCKING PROCESS ON THE EDT.

Executing external commands are inherently blocking actions, while not explicitly, taking into account needing to consume the output of the process or wanting to know about the processes termination, these would require you to perform some kind of blocking action. Don't do this on the EDT. It will cause you program to appear as if it's hung.

回答4:

You can use the Runtime.exec methods to run commands from within Java. The system enviroment variables are normally not visible from within the jvm. You could use a launcher, that submits these system enviroment properties as jvm properties to your java application.

回答5:

According to http://javarevisited.blogspot.de/2011/02/how-to-execute-native-shell-commands.html implementing the following into your code after including "java.lang.Runtime" should perfectly work:

try {

Process process = Runtime.getRuntime().exec("Command to be executed");

} catch (Exception e) {

e.printStackTrace(System.err);

}

来源：https://stackoverflow.com/questions/12716121/how-to-run-different-commands-from-java-code