java调用javascript

介绍

jdk1.6提供了对JavaScript的支持，使用的js引擎为Rhino，jdk1.8替换成了Nashorn。

使用

public class Client {
  public static void main(String[] args) throws IOException,
      ScriptException, NoSuchMethodException {
//获取javascript引擎
    ScriptEngineManager engineManager = new ScriptEngineManager();
    ScriptEngine scriptEngine = engineManager.getEngineByName("javascript");
    System.out.println(scriptEngine);
    invokeJsWithString(scriptEngine);
  }

  private static void invokeJsWithString(ScriptEngine scriptEngine)
      throws ScriptException, NoSuchMethodException {
    String code = "12 + 34";
//执行javascript语句
    Object result = scriptEngine.eval(code);
    System.out.println(result);
//绑定变量
    Bindings bindings = scriptEngine.createBindings();
    bindings.put("name", "lisi");
    scriptEngine.setBindings(bindings, ScriptContext.ENGINE_SCOPE);
//name为外部变量
    code = "function print(num1,num2) { return num1 + num2 + name; }";
    scriptEngine.eval(code);
//执行javascript函数
    result = ((Invocable) scriptEngine).invokeFunction("print", 4, 5);
    System.out.println(result);
  }
}

输出结果为

jdk.nashorn.api.scripting.NashornScriptEngine@61f8bee4
46
9lisi

spring对java中的API进行了一些简单的封装

public class Client {
  public static void main(String[] args) {
    StandardScriptEvaluator evaluator = new StandardScriptEvaluator();
    evaluator.setLanguage("javascript");
    Object result = evaluator.evaluate(new StaticScriptSource("12 + 34"));
    System.out.println(result);
  }
}

46