Jmeter beanshell to match and replace - jmeter

Question

I rarely do scripting and I have problem using reg expression using Jmeter's beanshell.
Basically, I have an output of 16 digits. I wanted to search the string, separate every 2nd character, and prepend with '0x' followed by a space, repeat for all 16 digits, lastly using vars.put into a self defined parameters. I have managed to do this in bash easily but not able to find solution with Beanshell Jmeter.
// get current date
var d = new Date();
// convert to epoch
var militime = d.getTime();
// convert to 16digit
//var nowtime1 = (long.valueOf(militime) * 1000);
var nowtime1 = militime * 1000;
var nowtime1 = nowtime1.replace(/({0,2})/g,"x0"); //I'm unsure of the syntax here
Does anyone has suggestion to improve?
This is sample output from my bash script using sed to format:
1495207922508835
0x14 0x95 0x20 0x79 0x22 0x50 0x88 0x35

Answer 1

Using Beanshell is some form of antipattern when it comes to creating JMeter scripts, you should consider using JSR223 Test Elements and Groovy language instead as Groovy is less resource intensive, has much better performance and it is more Java-compliant.
Coming back to your question, Groovy implementation of your requirement would be something like:
def now = "1495207922508835"
def result = new StringBuilder()
now.split("(?<=\\G..)").each {
result.append("0x").append(it).append(" ")
}
log.info(result.toString())
Demo:
See Groovy is the New Black guide to learn about why and how you should be using Groovy in JMeter tests.
NB: adding 0x doesn't really convert an integer into hex, you might want to consider Integer.toHexString() method instead.

Answer 2

I would simplify current time retrieval to System.currentTimeMillis() * 1000. Second, you are trying to manipulate number as if it's a string, but then you need to convert it to string. Regex itself is almost right. So the whole script looks like this:
now = "" + (java.lang.System.currentTimeMillis() * 1000);
result = now.replaceAll("(.{2})", "0x$1 ");
Example:
now result
1495215390956000 0x14 0x95 0x21 0x53 0x90 0x95 0x60 0x00
1495215441281000 0x14 0x95 0x21 0x54 0x41 0x28 0x10 0x00