通过脚本引擎 (jython) 从 Java 调用 Python？
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Calling Python from Java through scripting engine (jython)?
提问by griffin
I'm trying to call Jython from a Java 6 application using javax.script:
我正在尝试使用以下命令从 Java 6 应用程序调用 Jython javax.script：
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class jythonEx
{
public static void main (String args[]) throws ScriptException
{
ScriptEngineManager mgr = new ScriptEngineManager();
ScriptEngine pyEngine = mgr.getEngineByName("python");
try {
pyEngine.eval("print \"Python - Hello, world!\"");
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
This is causing a NullPointerException:
这会导致 NullPointerException：
java.lang.NullPointerException
at jythonEx.main(jythonEx.java:12)
Does anyone have any idea what I'm doing wrong here?
有谁知道我在这里做错了什么？
Edit:
编辑：
Thanks for the responses! I added jython.jar to the classpath and it runs properly:
感谢您的回复！我将 jython.jar 添加到类路径中，它运行正常：
java -cp "./;jython.jar" jythonEx
回答by OscarRyz
You have to register your engine first.
您必须先注册您的引擎。
From: ScriptEngineManager.getEngineByName:
来自：ScriptEngineManager.getEngineByName：
[...] first searches for a ScriptEngineFactory that has been registered as a handle [...] Returns null if no such factory was found
[...] 首先搜索已注册为句柄的 ScriptEngineFactory [...] 如果找不到这样的工厂，则返回 null
The user guide says to use it with JSR-223you have to:
用户指南说要将它与 JSR-223 一起使用，您必须：
As of Jython 2.5.1 an implementation of JSR 223 is bundled in jython.jar. Simply add jython to your CLASSPATH and ask for the python script engine.
从 Jython 2.5.1 开始，JSR 223 的实现捆绑在 jython.jar 中。只需将 jython 添加到您的 CLASSPATH 并请求 python 脚本引擎。
Did you do that already?
你已经这样做了吗？
EDITAbout your comment: I think you should open a new question, you'll get better answers.
编辑关于您的评论：我认为您应该提出一个新问题，您会得到更好的答案。
回答by Petre Maierean
You'd probably have to register a ScriptEngineFactory for'python'
您可能必须为“python”注册一个 ScriptEngineFactory
