如何使用Rhino在Javascript中将Java类中的方法添加为全局函数？ [英] How can I add methods from a Java class as global functions in Javascript using Rhino?

问题描述

我有一个简单的Java类，它有一些方法：

I have a simple Java class that has some methods:

public class Utils {
    public void deal(String price, int amount) {
        // ....
    }
    public void bid(String price, int amount) {
        // ....
    }
    public void offer(String price, int amount) {
        // ....
    }
}

我想创建这个类的实例并允许Javascript代码直接调用这些方法，如下所示：

I would like to create an instance of this class and allow the Javascript code to call the methods directly, like so:

deal("1.3736", 100000);
bid("1.3735", 500000);

我现在唯一可以解决的方法是使用

The only way I could figure out for now was to use

ScriptEngine engine = new ScriptEngineManager().getEngineByName("js");
engine.put("utils", new Utils());

然后使用 utils.deal（...）在Javascript代码中。我也可以在Javascript中为每个方法编写包装函数，但应该有一种更简单的方法来自动为类的所有公共方法执行此操作。

and then use utils.deal(...) in the Javascript code. I can also write wrapper functions in Javascript for each method, but there should be a simpler way to do this automatically for all the public methods of a class.

推荐答案

我对Rhino并不熟悉，但这样的事情应该有效：

I'm not real familiar with Rhino, but something like this should work:

for(var fn in utils) {
  if(typeof utils[fn] === 'function') {
    this[fn] = (function() {
      var method = utils[fn];
      return function() {
         return method.apply(utils,arguments);
      };
    })();
  }
}

只需循环遍历 utils ，对于每个函数，创建一个调用它的全局函数。

Just loop over the properties of utils,and for each one that is a function, create a global function that calls it.

编辑：我让这个工作在一个Groovy脚本，但我必须在绑定中设置utils，而不是在代码中设置引擎：

I got this working in a Groovy script, but I had to set utils in the bindings, not on the engine like in your code:

import javax.script.*

class Utils {
   void foo(String bar) {
      println bar
   }   
}

ScriptEngine engine = new ScriptEngineManager().getEngineByName("js");

engine.eval("""
for(var fn in utils) {
  if(typeof utils[fn] === 'function') {
    this[fn] = (function() {
      var method = utils[fn];
      return function() {
         return method.apply(utils,arguments);
      };
    })();
  }
}

foo('foo'); // prints foo, sure enough
""",new SimpleBindings("utils":new Utils()))

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