Java-Scripting

1. 简单调用

/**
 * simple,默认java.*包中的API已经倒入到engine中。你可以使用那些API
 * @throws Exception
 */
private static void invoke1() throws Exception{
    ScriptEngineManager engineManager = new ScriptEngineManager();
    ScriptEngine engine = engineManager.getEngineByName("javascript");
    //根据“脚本语言名称”获取执行引擎，java本身默认只支持javascript，对于其他脚本，可以
    //使用第三方包(apache bsf,不过不是很好用)
    //getEngineByName方法每次都会创建一个心的Engine对象
    //java.lang包默认已经导入
    String script = "var message = 'This is javascript.';println(message);var total = 2;";
    engine.eval(script);
    Double total = (Double)engine.get("total");
    System.out.println(total);
}

2. 向JS脚本传递参数

/**
 * 向当前engine调用中put参数，并交给script
 * @throws Exception
 */
private static void invoke2() throws Exception{
    ScriptEngineManager engineManager = new ScriptEngineManager();
    ScriptEngine engine = engineManager.getEngineByName("javascript");
    String script = "for(var i=0;i< times;i++) {println(i);}";
    engine.put("times", 10);
    engine.eval(script);
}

 3. 在JS中使用java对象的方法或属性

private static void invoke3() throws Exception{
    ScriptEngineManager engineManager = new ScriptEngineManager();
    ScriptEngine engine = engineManager.getEngineByName("javascript");
    String script = "println(string + ',length:' + string.length);";
    engine.put("string", "javascript");
    engine.eval(script);
}