使用 javax.scripting 从 Java 进行 Jython 调用

Question

我正在尝试使用 Jython 将一个小型 Python 脚本集成到我拥有的 Java 程序中。我似乎无法使用该javax.script包获取 python/jython 引擎。

我从这里获取了代码，并做了一些小的添加来生成：

andrew@asimov:~$ echo $CLASSPATH
/opt/jython/jython.jar:.
andrew@asimov:~$ java Engines
The following 2 scripting engines were found

Engine name: jython
    Version: 2.7.0
    Language: python
    Engine supports the following extensions:
            py
    Engine has the following short names:
            python
            jython
=========================
Engine name: Rhino
    Version: Rhino 1.7 release 4 2013 08 27
    Language: ECMAScript
    Engine supports the following extensions:
            js
    Engine has the following short names:
            js
            rhino
            JavaScript
            javascript
            ECMAScript
            ecmascript
=========================
python engine is null: true
js engine is null: false
andrew@asimov:~$

我添加的代码是：

String[] engineNames = new String[] {
        "python", "js"
};

for (String engineName : engineNames) {
    ScriptEngine engine = manager.getEngineByName(engineName);
    System.out.printf("%s engine is null: %s\n", engineName, (engine == null));
}

为什么我得到的是 null python 引擎？

我遇到了这个 bug，它似乎表明那里有（或曾经有）一个 jython-engine.jar，但如果我能找到它，我就被绞死了。

Answer 1

根据这个问题，使用jython-standalone.jar而不是jython.jar返回一个非空引擎：

andrew@asimov:~$ export CLASSPATH=jython-standalone-2.7.0.jar:.
andrew@asimov:~$ java Engines | tail -11
Engine name: jython
    Version: 2.7.0
    Language: python
    Engine supports the following extensions:
            py
    Engine has the following short names:
            python
            jython
=========================
python engine is null: false
javascript engine is null: false
andrew@asimov:~$

（在我的 pom.xml 中，我使用了<artifactId>jython-standalone</artifactId>）

很好奇，但至少我可以继续前进。