捕获java中的javascript返回值 [英] Capture the javascript return value in java

问题描述

通过使用Java Sripting API，我可以在Java中执行JavaScript。但是，有人可以解释如何从Java中获取JS的返回值吗？在下面的示例中，我可以使用

By using Java Sripting API, I am able to execute JavaScript within Java. However, can someone please explain how to capture the return value from a JS in Java? In the example below, can I invoke the script2 using

inv.invokeFunction("getValue", "Number", "2);

如何从script2获取返回值？

How can I get the return value from script2?

import javax.script.*;

public class InvokeScriptFunction {
public static void main(String[] args) throws Exception {
    ScriptEngineManager manager = new ScriptEngineManager();
    ScriptEngine engine = manager.getEngineByName("JavaScript");

    // JavaScript code in a String
    String script1 = "function hello(name) {print ('Hello, ' + name);}";
    String script2 = "function getValue(a,b) { if (a==="Number") return 1; 
                     else return b;}";
    // evaluate script
    engine.eval(script1);
    engine.eval(script2);

    Invocable inv = (Invocable) engine;

    inv.invokeFunction("hello", "Scripting!!" );  //This one works.      
 }
}

推荐答案

这是您获得该返回值的方式。

This is how you will get that return value.

String returnValue = (String)inv.invokeFunction("hello", "Scripting!!" );

脚本2相同，只需相应更改通话。

Same for script 2, just change the call accordingly.

Invocable中的invokeFuntion方法返回一个Object。因此，我们必须在使用之前将其类型化为适当的类型。

The invokeFuntion method from Invocable returns an Object. So, we must type-cast it to the appropriate type before using it.

参考

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