Jython,只使用来自Python和Java的方法？

Question

这里是一个示例代码，重现我得到的错误，也得到一个工作示例从您的有益的答复！

（好的，添加一个关于从生成的Python/Jython结果映射回Java对象的其他问题）

(@Joonas，对不起，我修改了我的代码，现在我无法返回到我以前的错误）

import org.python.core.Py;
import org.python.core.PyList;
import org.python.core.PyTuple;
import org.python.core.PyObject;
import org.python.core.PyString;
import org.python.core.PySystemState;
import org.python.util.PythonInterpreter;

interface MyInterface {
    public PyList getSomething(String content, String glue, boolean bool);
}
class MyFactory {

    @SuppressWarnings("static-access")
    public MyFactory() {
        String cmd = "from mymodule import MyClass";
        PythonInterpreter interpreter = new PythonInterpreter(null, new PySystemState());

        PySystemState sys = Py.getSystemState();
        sys.path.append(new PyString("C:/jython2.5.2/Lib"));

        interpreter.exec(cmd);
        jyObjClass = interpreter.get("MyClass");
    }

    public MyInterface createMe() {
        PyObject myObj = jyObjClass.__call__();
        return (MyInterface)myObj.__tojava__(MyInterface.class);
    }

    private PyObject jyObjClass;
}


public class Main {

    public static void main(String[] args) {

    /*
// with only :
    PythonInterpreter interpreter = new PythonInterpreter();

     i get : 
Exception in thread "main" Traceback (most recent call last):
  File "<string>", line 1, in <module>
LookupError: no codec search functions registered: can't find encoding 'iso8859_1'

which is probably due to the : 
#!/usr/bin/env python
# -*- coding: latin-1 -*-

// yes i am from France, so my - sorry for that - bad english ;) and have to deal with non 127 ascii chars :)
     */

    PythonInterpreter interpreter = new PythonInterpreter(null, new PySystemState());

    PySystemState sys = Py.getSystemState();
    sys.path.append(new PyString("C:/jython2.5.2/Lib"));

    interpreter.exec("from mymodule import getSomething"); 
    PyObject tmpFunction = interpreter.get("getSomething"); 
    System.err.println(tmpFunction.getClass()); 
    MyInterface i = (MyInterface) tmpFunction.__tojava__(MyInterface.class); 
    System.err.println(i.getSomething("test", " - ", true));
    for (Object x : i.getSomething("test", " - ", true)) {
        System.out.println(x);
        // How can i get back an equivallent of the Python _"for (a, b) in getSomething:"_ 
        // with _"a"_ being PyUnicode or better String, and _"b"_ being boolean ?
    }

    // ^^ so adapting Daniel Teply solution works ! Thanks to him... 
    // BTW the part below did not work : but i may have missed or/and also mixed many things :/
    // i feel Jython damned hard to dive in :/ 
    // and really hope that the sample that i post and answers that i get will help others to swim!

    try {
        MyFactory factory = new MyFactory();
        MyInterface myobj = factory.createMe();

        PyList myResult = myobj.getSomething("test", " - ", true);
        System.out.println(myResult);
    }
    catch (Exception e) {
        System.out.println(e);
        // produce a : java.lang.ClassCastException: org.python.core.PySingleton cannot be cast to MyInterface
        // EDIT : see below last edit, this error may be due to my forgotten heritage from interface in the python code!
    }

    System.exit(-1);
    }
}

Python部分：（mymodule.py）

#!/usr/bin/env python
# -*- coding: latin-1 -*-

class MyClass:
    def __init__(selfself):
        pass
    def getSomething(self, content, glue = '', bool = True):
        for x in range(5):
            yield (glue.join(map(str, (content, x, chr(97 + x))))), bool
        #return list()

def getSomething(content, glue = '', bool = True):
    print "test"
    myclass = MyClass()
    return list(myclass.getSomething(content, glue, bool))

def main():
    test()

if __name__ == "__main__":
    main()

编辑：

部分回答我自己，对于内部的问题（内部评论）:
（实际上我觉得我的答案和代码很难看，但它工作，似乎可以取消元组。我不知道是否有更好的jythonic方法来做这件事，如果是的话，我真的很感兴趣：））

for (Object x : i.getSomething("test", " - ", true)) {
    System.out.println(x);
    // How can i get back an equivallent of the Python _"for (a, b) in getSomething:"_ 
    // with _"a"_ being PyUnicode or better String, and _"b"_ being boolean ?

    // answering myself here :
    PyTuple mytuple = (PyTuple) x; // casting back x as PyTuple, can we have a java equivalent to _`(a, b) = x_ ? not sure...
    PyObject a = mytuple.__getitem__(0);
    PyObject b = mytuple.__getitem__(1);
    String aS = a.toString(); // mapping a unicode python string to java is as simple?
    boolean bB = b.toString().toLowerCase().equals("true");
    System.out.println(mytuple + "[" + aS + "][" + b + "][" + bB + "]");

编辑:

回答我自己关于“Produce a：”java.lang.ClassCastException：org.python.core.PySingleton不能强制转换到MyInterface“的部分...我的大部分误解和错误都是由于我忘记了从Python部分处理Java！（请参阅上面的代码，我没有更正它，因为它不是我的主要问题，而且在它的实际形式中，它是关于这个主要问题的有效答案，这要感谢Daniel和Joonas帮助我理解）。因此，对于工厂范例，不要忘记向其Python文件添加适当的导入：

from testjython.interfaces import MyInterface #// defining method inside a MyInterface.java

class MyClass(MyInterface):
    [...]

我遇到的另一个困难是正确处理进口和包装。顺便说一句，将此代码添加到上层代码将产生一个TypeError：不能转换为org.python.core.pylist但这是另一个问题...

Answer 1

您可以使用pyobject.__call__(object...args)调用任何可调用的Python对象。您可以从java端获得表示您的函数的PyFunction，就像您的示例获得python employee类一样。

或者，您可以通过调用从Python解释器中检索的函数__tojava__(interface.class)将其隐藏在java端的单个方法接口之后。详细示例（实际测试！）：python文件：

def tmp():
    return "some text"

Java：

public interface I{
    public String tmp();
}

public static void main(String[] args) {
    PythonInterpreter interpreter = new PythonInterpreter();
    interpreter.exec("from test import tmp");
    PyObject tmpFunction = interpreter.get("tmp");
    System.err.println(tmpFunction.getClass());
    I i = (I) x.__tojava__(I.class);
    System.err.println(i.tmp());

}

class org.python.core.PyFunction
some text