在Python子进程与os.system中执行Jar

Question

I am learning how to exec a jar in python. I found two ways, 1) subprocess and 2) os.system. In my code, only os.system works and am I wondering why.

Here is my code.

import os

os.chdir('/Users/Jim/Desktop')

import subprocess
from subprocess import Popen, PIPE, STDOUT
p = Popen(['java','-cp','dfp-api-1.0-SNAPSHOT-standalone.jar', \
           'dfp.axis.v201611.lineitemservices.GetAllLineItems', \
           '-c ads.properties', \
           '-o lineitem-prev.txt', \
           '-l 2017-02-16X00:00:00'], \
          stdout=PIPE, stderr=STDOUT)
for line in p.stdout:
    print line

os.system('java -cp dfp-api-1.0-SNAPSHOT-standalone.jar dfp.axis.v201611.lineitemservices.GetAllLineItems -c ads.properties -o lineitem.txt -l 2017-02-20X00:00:00')

The subprocess returns these error messages:

Exception in thread "main" java.lang.NullPointerException
at java.text.SimpleDateFormat.parse(Unknown Source)
at java.text.DateFormat.parse(Unknown Source)
at dfp.axis.v201611.lineitemservices.GetAllLineItems.executeIngest(GetAllLineItems.java:46)
at dfp.axis.v201611.GoogleApiHandler.lightTheFuse(GoogleApiHandler.java:103)
at dfp.axis.v201611.lineitemservices.GetAllLineItems.main(GetAllLineItems.java:99)

Thank you for your input. Jim

Answer 1

Your java program is saying that no date has been passed. It occurs because you're not passing the arguments in the right way. Try out this code:

from subprocess import Popen, PIPE, STDOUT
p = Popen(['java','-cp','dfp-api-1.0-SNAPSHOT-standalone.jar', \
           'dfp.axis.v201611.lineitemservices.GetAllLineItems', \
           '-c', 'ads.properties', \
           '-o', 'lineitem-prev.txt', \
           '-l', '2017-02-16X00:00:00'], \
          stdout=PIPE, stderr=STDOUT)

or this one

from subprocess import Popen, PIPE, STDOUT
p = Popen('java -cp dfp-api-1.0-SNAPSHOT-standalone.jar dfp.axis.v201611.lineitemservices.GetAllLineItems -c ads.properties -o lineitem.txt -l 2017-02-20X00:00:00',
          shell=True, stdout=PIPE, stderr=STDOUT)