Question

我是Jython的新手。我试图通过Java程序（使用Jython）执行python脚本。在python脚本中，我试图调用一些外部库（称为petl）的方法。当我尝试使用python（As：python script.py）执行脚本时，它执行没有任何问题。但是当我尝试使用Jython（As：jython script.py）访问脚本时，它会给我以下错误。

P.S：我可以毫无问题地运行简单的python脚本。但是当我尝试通过脚本访问外部库函数时，它会给我一个错误。

任何人都可以给我一个解决方法或一些建议吗？提前谢谢。

Python脚本：

import petl as etl

table1 = etl.fromcsv('Books.csv')
table2 = etl.sort(table1, 'ACCOUNT_ID')
etl.tocsv(table2, source='NewBooks.csv',encoding='utf-8')

错误堆栈：

Traceback (most recent call last):
  File "test1.py", line 5, in <module>
    etl.tocsv(table2, source='NewBooks.csv',encoding='utf-8')
  File "C:\Jython\Lib\site-packages\petl\io\csv.py", line 106, in tocsv
    tocsv_impl(table, source=source, encoding=encoding, errors=errors,
  File "C:\Jython\Lib\site-packages\petl\io\csv_py2.py", line 50, in tocsv_impl
    _writecsv(table, source=source, mode='wb', **kwargs)
  File "C:\Jython\Lib\site-packages\petl\io\csv_py2.py", line 74, in _writecsv
    for row in rows:
  File "C:\Jython\Lib\site-packages\petl\transform\sorts.py", line 271, in _iter
nocache
    hdr = next(it)
  File "C:\Jython\Lib\site-packages\petl\io\csv_py2.py", line 30, in __iter__
    codec = getcodec(self.encoding)
  File "C:\Jython\Lib\site-packages\petl\io\base.py", line 12, in getcodec
    codec = codecs.lookup(encoding)
        at org.python.core.codecs.normalizestring(codecs.java:62)
        at org.python.core.codecs.access$200(codecs.java:29)
        at org.python.core.codecs$CodecState.lookup(codecs.java:1695)
        at org.python.core.codecs.lookup(codecs.java:58)
        at org.python.modules._codecs.lookup(_codecs.java:57)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)

java.lang.NullPointerException: java.lang.NullPointerException

Answer 1

在调用fromcsv（）和tocsv（）函数时，必须显式传递编码值。

mysql> SHOW FULL PROCESSLIST;
+-----+------------------+-----------------+---------+---------+------+--------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Id  | User             | Host            | db      | Command | Time | State        | Info                                                                                                                                                                                                          |
+-----+------------------+-----------------+---------+---------+------+--------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 253 | whitewall        | localhost:39377 | mailing | Query   |    4 | Sending data | 
SELECT
    contacts.ID,
    contacts.RATING,
    mails.MANDRILL_ID
FROM contacts
    LEFT JOIN mails
        ON mails.CONTACT_ID = contacts.ID
HAVING mails.MANDRILL_ID = 'fea4b3b036b44655a7e24121ac359d0a' |

无法以Jython的身份运行脚本。但是使用python没有任何问题

1 个答案: