Question

Nashorn脚本引擎不会将“com”和“org”对象/命名空间从全局范围共享到引擎范围。因为“com”和“org”是引擎可用的Java包。

在示例中，我将a和org变量放入engine2的全局范围。

a = 3已共享
org = 10存在于GLOBAL_SCOPE中，但未与ENGINE_SCOPE

代码：

public static void main(String[] args) throws ScriptException {
    ScriptEngineManager manager = new ScriptEngineManager();
    ScriptEngine engine = manager.getEngineByName("JavaScript");
    Bindings bindings = engine.createBindings();
    bindings.put("a", 3);
    bindings.put("org", 10);
    log("bingings-org", bindings.get("org"));
    manager.setBindings(bindings);

    ScriptEngine engine2 = manager.getEngineByName("JavaScript");
    log("global-a", engine2.getBindings(ScriptContext.GLOBAL_SCOPE).get("a"));
    log("local-a", engine2.get("a"));
    log("global-org", engine2.getBindings(ScriptContext.GLOBAL_SCOPE).get("org"));
    log("local-org", engine2.get("org"));
}

有没有办法将“org”和“com”软件包从Global scope分享到Local scope？
是否存在描述情况的文件？

Answer 1

搜索脚本全局变量时，搜索顺序首先是ENGINE_SCOPE，然后是GLOBAL_SCOPE。 Nashorn引擎的ENGINE_SCOPE绑定是包装为javax.script.Bindings对象的ECMAScript“全局”对象。正如您所观察到的，ENGINE_SCOPE具有“org”，“com”等的映射 - 这是Java包前缀对象。因此，这些将隐藏GLOBAL_SCOPE绑定中的任何“org”，“com”等。两种解决方案：

您将“context”变量暴露给脚本。因此，您可以使用相同的方法获取GLOBAL_SCOPE映射。

private static void log(String msg, Object obj) {
    System.out.println(msg + " " + obj);
}

public static void main(String[] args) throws ScriptException {
    ScriptEngineManager manager = new ScriptEngineManager();
    Bindings bindings = new SimpleBindings();
    bindings.put("a", 3);
    bindings.put("org", 10);
    log("bingings-org", bindings.get("org"));
    manager.setBindings(bindings);

    ScriptEngine engine = manager.getEngineByName("JavaScript");
    log("global-a", engine.getBindings(ScriptContext.GLOBAL_SCOPE).get("a"));
    log("local-a", engine.get("a"));
    log("global-org", engine.getBindings(ScriptContext.GLOBAL_SCOPE).get("org"));
    log("local-org", engine.get("org"));

    // Use "context" to access GLOBAL_SCOPE "org" from script
    engine.eval(
        "var GLOBAL_SCOPE = javax.script.ScriptContext.GLOBAL_SCOPE;\n" +
        "var g = context.getBindings(GLOBAL_SCOPE);\n" +
        "print(g.get('org'))"); 
}

您可以删除ENGINE_SCOPE Bindings中的“org”，“com”等。

private static void log(String msg, Object obj) {
    System.out.println(msg + " " + obj);
}

public static void main(String[] args) throws ScriptException {
    ScriptEngineManager manager = new ScriptEngineManager();
    Bindings bindings = new SimpleBindings();
    bindings.put("a", 3);
    bindings.put("org", 10);
    log("bingings-org", bindings.get("org"));
    manager.setBindings(bindings);

    ScriptEngine engine = manager.getEngineByName("JavaScript");
    log("global-a", engine.getBindings(ScriptContext.GLOBAL_SCOPE).get("a"));
    log("local-a", engine.get("a"));
    log("global-org", engine.getBindings(ScriptContext.GLOBAL_SCOPE).get("org"));
    log("local-org", engine.get("org"));
    // "org" in ENGINE_SCOPE hides GLOBAL_SCOPE "org".
    // delete the "org" in ENGINE_SCOPE
    // you could delete "org" from Java code as well using
    // "remove" method of Bindings object
    engine.eval("delete org");
    System.out.println("after deleting ENGINE_SCOPE org");
    log("local-org", engine.get("org"));
}

Nashorn ScriptEngine。如何将“org”对象从全局范围共享到本地范围？

1 个答案: