I am writing a Java application in IntelliJ IDE. The application used Rserve package to connect to R and perform some functions. When I want to run my code for the first time, I have to launch R in the command line and start the Rserve as a daemon, which looks something like this:
R
library(Rserve)
Rserve()
After doing this, I can easily access all the function in R without any errors. However, since this Java code would be bundled as an executable file, so is there a way that Rserve() is invoked automatically as soon as the code is run so that I have to skip this manual step of starting Rserve using the command line?
Here is the code for the Class
I wrote to get Rserve
working from Java
public class InvokeRserve {
public static void invoke() {
String s;
try {
// run the Unix ""R CMD RServe --vanilla"" command
// using the Runtime exec method:
Process p = Runtime.getRuntime().exec("R CMD RServe --vanilla");
BufferedReader stdInput = new BufferedReader(new
InputStreamReader(p.getInputStream()));
BufferedReader stdError = new BufferedReader(new
InputStreamReader(p.getErrorStream()));
// read the output from the command
System.out.println("Here is the standard output of the command:\n");
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
}
// read any errors from the attempted command
System.out.println("Here is the standard error of the command (if any):\n");
while ((s = stdError.readLine()) != null) {
System.out.println(s);
}
// System.exit(0);
}
catch (IOException e) {
System.out.println("exception happened - here's what I know: ");
e.printStackTrace();
System.exit(-1);
}
}
}
I know this question has been asked a long back . I think You have the answer. But the below answer may help others. That's why I am posting my answer. answer:- Instead of going again and again to the R console to start Rserve. One thing you can do is you can write a java program to start Rserve.
Below code you can use in a java program to start Rserve. https://www.sitepoint.com/community/t/call-linux-command-from-java-application/3751. This is the link where you will get the code to run a linux command from java.I have changed the command only and posting below.
package javaapplication13;
import java.io.*;
public class linux_java {
public static void main(String[] args) {
try {
String command ="R CMD Rserve";
BufferedWriter out = new BufferedWriter(new FileWriter(
new File(
"/home/jayshree/Desktop/testqavhourly.tab"), true));
final Process process = Runtime.getRuntime().exec(command);
BufferedReader buf = new BufferedReader(new InputStreamReader(
process.getInputStream()));
String line;
while ((line = buf.readLine()) != null) {
out.write(line);
out.newLine();
}
buf.close();
out.close();
int returnCode = process.waitFor();
System.out.println("Return code = " + returnCode);
} catch (Exception e) {
e.printStackTrace();
}
}
}
来源:https://stackoverflow.com/questions/32373372/how-to-start-rserve-automatically-from-java