使用java运行python

Question

如何修复java中的以下错误？

要求:使用java运行python程序

支持库:jython-standalone-2.7.0.jar

安装的python : python 3.6.0

public static void main(String[] args) throws FileNotFoundException, ScriptException, IOException {
    System.out.println("Hello world!!");
    //option 1
    StringWriter writer = new StringWriter(); //ouput will be stored here

    ScriptEngineManager manager = new ScriptEngineManager();
    ScriptContext context = new SimpleScriptContext();

    context.setWriter(writer); //configures output redirection

    ScriptEngine engine = manager.getEngineByName("python");
    PythonInterpreter interpreter = new PythonInterpreter();

    interpreter.exec("import sys\nsys.path.append('C:\\Users\\johns\\AppData\\Local\\Programs\\python\\python36\\Lib\\site-packages')");
    engine.eval(new FileReader("C:\\Users\\johns\\Desktop\\python\\pytest.py"), context);
    System.out.println("");
    System.out.println(writer.toString());
//option 2
   // String execCmd = execCmd("python 
C:\\Users\\johns\\Desktop\\python\\pytest.py");
   // System.out.println("From Cmd Prompt" + execCmd);

}

public static String execCmd(String cmd) throws java.io.IOException {
    Process proc = Runtime.getRuntime().exec(cmd);
    java.io.InputStream is = proc.getInputStream();
    java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A");
    String val = "";
    if (s.hasNext()) {
        val = s.next();
    } else {
        val = "";
    }
    return val;
}

错误消息：

Exception in thread "main" javax.script.ScriptException: AttributeError: 'tuple' object has no attribute 'major' in <script> at line number 1
at org.python.jsr223.PyScriptEngine.scriptException(PyScriptEngine.java:202)
at org.python.jsr223.PyScriptEngine.eval(PyScriptEngine.java:42)
at org.python.jsr223.PyScriptEngine.eval(PyScriptEngine.java:47)
at pythonproj.PythonProj.main(PythonProj.java:47)
Caused by: Traceback (most recent call last):
File "<script>", line 1, in <module>
File "C:\Users\johns\AppData\Local\Programs\python\python36\Lib\site- 
packages\pytesseract\__init__.py", line 1, in <module>
from .pytesseract import (
File "C:\Users\johns\AppData\Local\Programs\python\python36\Lib\site- 
packages\pytesseract\pytesseract.py", line 10, in <module>
from PIL import Image
File "C:\Users\johns\AppData\Local\Programs\python\python36\Lib\site- 
packages\PIL\Image.py", line 31, in <module>
from ._util import py3
File "C:\Users\johns\AppData\Local\Programs\python\python36\Lib\site- 
packages\PIL\_util.py", line 3, in <module>
py3 = sys.version_info.major >= 3
AttributeError: 'tuple' object has no attribute 'major'

at org.python.core.Py.AttributeError(Py.java:205)
at org.python.core.PyObject.noAttributeError(PyObject.java:1013)
at org.python.core.PyObject.__getattr__(PyObject.java:1008)

建议，这是使用jython运行python程序或通过调用上述代码中的选项2的命令进程的更好方法。

Answer 1

你得到的异常似乎是由a jython bug引起的(这显然是用jython-2.7.1修复的)。

关于您的另一个问题；如果您只想运行脚本，而不以任何方式与解释器交互，并且您知道系统上安装了合适的python版本，那么使用进程可能会容易得多，并且可以避免jython的这种和潜在的其他问题。

Answer 2

由于jython项目处于非活动状态，而不是Python3，因此不是最新的(请参阅注释)，因此将python.exe作为系统可执行文件启动的option2是很好的选择。

它不能按照你编码的方式工作，因为Runtime.exec不执行DOS，而是直接执行一个可执行文件。启动的是python.exe，您的py文件是该命令的一个参数

以下是启动它的一种方法

public static String execPython(String pythonFile) throws java.io.IOException {

    // modification here: provide a String array with "python" as first argument, 
    // you may add other argument of your python program

    Process proc = Runtime.getRuntime().exec(new String[] {"python",pythonFile});

    java.io.InputStream is = proc.getInputStream();
    java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A");
    String val = "";
    if (s.hasNext()) {
        val = s.next();
    } else {
        val = "";
    }
    return val;
}

public static void main(String[] args) {
    try {
        String stdStream = execPython("C:\\Users\\johns\\Desktop\\python\\pytest.py");
        System.out.println(stdStream);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}