Catch Java Exception with PHP shell_exec

Question

Is there any way to catch a java exception from a JAR call by a php script? I have (!) to use some external JAVA libraries, which throws Exceptions. The Question is how can i extract valuable information for developers and show some explanation to the customer?

PHP Script

 try{
   $cmd = "java -jar myjar.jar";
   $output = shell_exec(escapeshellcmd($cmd));
 }
 catch(Javaexception $e){
   //do some error handling ....
 }

Java Jar

//....
public class Main{

public static void main(String[] args){
     throw new Exception("Testexception");
  }
}
//...

Answer 1

shell_exec only returns a String or Null, so you can't catch the Java Exception like that, try to create your own Exception and "catch it" with a if

$cmd = "java -jar myjar.jar";
$output = shell_exec(escapeshellcmd($cmd));
if($output == 'expected output') throw new MyException();

Answer 2

Basic answer: not directly.

You can use exit statuses to communicate processing status from the Java application.

In Java:

public class Main{
public static void main(String[] args){
       try {
           // work
       } catch (MyException e) {
           // handle error
           // write exception to file or STDOUT 
           System.exit(1);
       }
    }
}

In PHP you can get the exit status via return_var in exec call:

string exec ( string $command [, array &$output [, int &$return_var ]] )

You can also write Exception details to STDOUT or file and process its content in the PHP when status code is non 0.