jython - jython-standalone-2.7.0.jar 和 jython-2.7.0.jar 有什么区别

Question

我写了一个Java例子，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 ，如果我使用:

<dependency>
    <groupId>org.python</groupId>
    <artifactId>jython-standalone</artifactId>
    <version>2.7.0</version>
</dependency>

然后我可以运行 java -jar target/jython-example-1.0-SNAPSHOT.jar成功了，顺便说一句，我用了 maven-assembly-plugin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>

然后当我运行 java -jar target/jython-example-1.0-SNAPSHOT.jar ，我总是会收到以下错误:

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

看来 pyEngine是 null .

所以我想知道 jython-standalone-2.7.0.jar 和有什么区别和 jython-2.7.0.jar

Answer 1

我刚刚发现的一个带有相同错误的问题是 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，它在提供的 jar 中正确包含 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:如果您直接从 Jython 站点下载 jar，它会正确地包含 lib 文件夹。这只是 Maven 存储库版本。