Question

我正在尝试调用python函数从java（groovy）中传递HashMap。 python函数对输入映射中的每个值进行平方，并返回具有相同键的方形字典。

JythonTest.groovy

import org.python.util.PythonInterpreter
import org.python.core.*;

class JythonTest 
{
    static main(def args) 
    {
        PythonInterpreter pi;

        pi = new PythonInterpreter()
        pi.exec("from py1 import square3")
        PyFunction pf = (PyFunction)pi.get("square3")

        def map = ["value1":1,"value2":2,"value3":3]     //groovy map   
        PyDictionary pyDict = new PyDictionary(map)
        pf.__call__(pyDict)         //this is line 16 at which according to stack trace the exception is originated (as python function call occurs here)
    }
}

py1.py

def square3(map):
    squareMap = {}
    for k,v in map.items():        #this is line 3 where according to stack trace exception is occurring
        squareMap[k] = v*v
    return squareMap

但我收到以下错误：

Exception in thread "main" Traceback (most recent call last):
  File "__pyclasspath__/py1.py", line 3, in square3
java.lang.ClassCastException: java.lang.String cannot be cast to org.python.core.PyObject

    at org.python.core.PyDictionary.dict_items(PyDictionary.java:659)

    at org.python.core.PyDictionary$dict_items_exposer.__call__(Unknown Source)

    at org.python.core.PyObject.__call__(PyObject.java:449)

    at py1$py.square3$1(__pyclasspath__/py1.py:5)

    at py1$py.call_function(__pyclasspath__/py1.py)

    at org.python.core.PyTableCode.call(PyTableCode.java:167)

    at org.python.core.PyBaseCode.call(PyBaseCode.java:138)

    at org.python.core.PyFunction.__call__(PyFunction.java:413)

    at org.python.core.PyFunction.__call__(PyFunction.java:408)

    at org.python.core.PyFunction$__call__.call(Unknown Source)

    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)

    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:110)

    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:122)

    at JythonTest.main(JythonTest.groovy:16)


java.lang.ClassCastException: java.lang.ClassCastException: java.lang.String cannot be cast to org.python.core.PyObject

在异常堆栈跟踪中，它说异常在python文件第3行。但是当我从python本身调用python函数时，比如在py1.py的末尾附加下面的行：

a = square3({"val1":1,"val2":2})
print(a)

我得到以下输出：

{'val2': 4, 'val1': 1}

那么为什么从java调用python函数会失败？我不知道这里出了什么问题。为什么要调用pf.__call__(pyDict)抛出此类异常？

Java中使用PythonInterpreter时的java.lang.ClassCastException

0 个答案: