我写了一个Java示例，代码是：
import org.python.core.PyObject;
import org.python.util.PythonInterpreter;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import java.util.List;
class JythonExample {
public static void main(String args[]) throws ScriptException {
listEngines();
ScriptEngineManager mgr = new ScriptEngineManager();
ScriptEngine pyEngine = mgr.getEngineByName("python");
try {
pyEngine.eval("print \"Python - Hello, world!\"");
} catch (Exception ex) {
ex.printStackTrace();
}
final PythonInterpreter interpreter = new PythonInterpreter();
interpreter.exec("print \"Python - Hello, world!\"");
PyObject result = interpreter.eval("2 + 3");
System.out.println(result.toString());
}
public static void listEngines(){
ScriptEngineManager mgr = new ScriptEngineManager();
List<ScriptEngineFactory> factories =
mgr.getEngineFactories();
for (ScriptEngineFactory factory: factories) {
System.out.println("ScriptEngineFactory Info");
String engName = factory.getEngineName();
String engVersion = factory.getEngineVersion();
String langName = factory.getLanguageName();
String langVersion = factory.getLanguageVersion();
System.out.printf("\tScript Engine: %s (%s)\n",
engName, engVersion);
List<String> engNames = factory.getNames();
for(String name: engNames) {
System.out.printf("\tEngine Alias: %s\n", name);
}
System.out.printf("\tLanguage: %s (%s)\n",
langName, langVersion);
}
}
}
在我的 pom.xml 中，如果我使用：
<dependency>
<groupId>org.python</groupId>
<artifactId>jython-standalone</artifactId>
<version>2.7.0</version>
</dependency>
顺便说一句，我可以成功地运行 java -jar target/jython-example-1.0-SNAPSHOT.jar ，我用 maven-assembly-plugin 来构建一个可运行的jar .
如果我使用：
<dependency>
<groupId>org.python</groupId>
<artifactId>jython</artifactId>
<version>2.7.0</version>
</dependency>
那么当我运行 java -jar target/jython-example-1.0-SNAPSHOT.jar 时，我总会收到以下错误：
ScriptEngineFactory Info
Script Engine: jython (2.7.0)
Engine Alias: python
Engine Alias: jython
Language: python (2.7)
ScriptEngineFactory Info
Script Engine: Oracle Nashorn (1.8.0_31)
Engine Alias: nashorn
Engine Alias: Nashorn
Engine Alias: js
Engine Alias: JS
Engine Alias: JavaScript
Engine Alias: javascript
Engine Alias: ECMAScript
Engine Alias: ecmascript
Language: ECMAScript (ECMA - 262 Edition 5.1)
java.lang.NullPointerException
at me.soulmachine.JythonExample.main(JythonExample.java:21)
Exception in thread "main" ImportError: Cannot import site module and its dependencies: No module named site
Determine if the following attributes are correct:
* sys.path: ['/home/programmer/src/github/JythonExample/JythonExample/target/Lib', '__classpath__', '__pyclasspath__/']
This attribute might be including the wrong directories, such as from CPython
* sys.prefix: /home/programmer/src/github/JythonExample/JythonExample/target
This attribute is set by the system property python.home, although it can
be often automatically determined by the location of the Jython jar file
You can use the -S option or python.import.site=false to not import the site module
似乎 pyEngine 是 null .
所以我想知道 jython-standalone-2.7.0.jar 和 jython-2.7.0.jar 之间有什么区别
2 回答
我刚刚发现的同一个错误的一个问题是maven build 2.7.0不包含lib文件夹 . 这可能是发布版本的构建错误 . 我不得不向上移动b2构建，它正确地包含了提供的jar中的lib文件夹 .
问题maven 2.7.0 jar：
<dependency> <groupId>org.python</groupId> <artifactId>jython-standalone</artifactId> <version>2.7.0</version> </dependency>包含lib文件夹的工作maven 2.7.1b2：
<dependency> <groupId>org.python</groupId> <artifactId>jython-standalone</artifactId> <version>2.7.1b2</version> </dependency>注意：如果直接从Jython站点下载jar，它确实包含lib文件夹 . 它只是maven存储库版本 .
我相信导致你的问题的主要区别是jython-standalone jar提供了Lib /（包含site.py），而jython jar却没有 .
https://github.com/scijava/jython-shaded对问题以及其他问题进行了更深入的描述，并提供了一个替代方法来解决说明中提到的一些问题 .
我没有使用scijava的经验：jython-shaded，但是我将它替换为你的pom（对于我的设置，我还必须将jdk.version更改为1.7和JythonExample）并运行示例 .