Jython CLASSPATH、sys.path 和 JDBC 驱动程序

Question

如何在运行时将 JDBC 驱动程序添加到 Jython？使用 CLASSPATH 可以，但使用 sys.path 不能与 zxJDBC 一起使用，即使该类已正确导入并且可以从 Jython 解释器提示符进行操作。

为什么这有效：

$ CLASSPATH=/tmp/jtds\-1.2.5.jar ./jython
*sys-package-mgr*: processing new jar, '/private/tmp/jtds-1.2.5.jar'
Jython 2.5.1 (Release_2_5_1:6813, Sep 26 2009, 13:47:54) 
[Java HotSpot(TM) 64-Bit Server VM (Apple Inc.)] on java1.6.0_20
Type "help", "copyright", "credits" or "license" for more information.
>>> from java.lang import Class
>>> Class.forName('net.sourceforge.jtds.jdbc.Driver')
<type 'net.sourceforge.jtds.jdbc.Driver'>

但这不起作用？

$ ./jython

Jython 2.5.1 (Release_2_5_1:6813, Sep 26 2009, 13:47:54) 
[Java HotSpot(TM) 64-Bit Server VM (Apple Inc.)] on java1.6.0_20
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.path.extend(['/tmp/jtds-1.2.5.jar'])
>>> from java.lang import Class
>>> Class.forName('net.sourceforge.jtds.jdbc.Driver')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:169)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)

java.lang.ClassNotFoundException: java.lang.ClassNotFoundException: net.sourceforge.jtds.jdbc.Driver
>>> sys.path
['', '/home/me/pkg/jython2.5.1/Lib/site-packages/distribute-0.6.13-py2.5.egg', '/home/me/pkg/jython2.5.1/Lib', '__classpath__', '__pyclasspath__/', '/home/me/pkg/jython2.5.1/Lib/site-packages', '/home/me/pkg/jython2.5.1/Lib/site-packages/setuptools-0.6c11-py2.5.egg-info', '/tmp/jtds-1.2.5.jar']
>>> import net.sourceforge.jtds.jdbc.Driver as Driver
>>> drv = Driver()
>>> drv
jTDS 1.2.5

它与类加载器有什么关系吗？

Answer 1

看起来甚至更新的链接也不再起作用（至少对于 jython-2.5.3b3 而言）。

这是一个工作版本：

def importJar(jarFile):
    '''
    import a jar at runtime (needed for JDBC [Class.forName])

    adapted from http://forum.java.sun.com/thread.jspa?threadID=300557
    Author: SG Langer Jan 2007 translated the above Java to Jython
    Author: [email protected] simplified and updated for jython-2.5.3b3

    >>> importJar('jars/jtds-1.2.5.jar')
    >>> import java.lang.Class
    >>> java.lang.Class.forName('net.sourceforge.jtds.jdbc.Driver')
    <type 'net.sourceforge.jtds.jdbc.Driver'>
    '''
    from java.net import URL, URLClassLoader
    from java.lang import ClassLoader
    from java.io import File
    m = URLClassLoader.getDeclaredMethod("addURL", [URL])
    m.accessible = 1
    m.invoke(ClassLoader.getSystemClassLoader(), [File(jarFile).toURL()])

if __name__ == '__main__':
    import doctest
    doctest.testmod()

---

我使用我的生产版本更新此要点。

Answer 2

解决方案很棘手，但一切都在此处进行了解释。