JDK8系列之JavaScript引擎Nashorn

Posted 2022-08-27 smileNicky

从JDK1.8开始，Java采用Nashorn作为嵌入式 javascript 引擎。JDK1.6和JDK1.7采用Rhino。Nashorn 支持 ECMAScript 5.1 规范，使用基于 JSR 292 的新语言特性，其中包含在 JDK 7 中引入的 invokedynamic，将 JavaScript 编译成 Java 字节码。

下面给出一些例子加深理解，一个最简单的例子，调用1+2，计算输出打印

package com.example.jdkexample.core.nashorn;


import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class NashornJavaScriptExample 


    public static void main(String[] args) throws ScriptException 
         ScriptEngineManager engineManager = new ScriptEngineManager();
        ScriptEngine scriptEngine = engineManager.getEngineByName("JavaScript");
        String foo = "1+2";
        System.out.println(scriptEngine.eval(foo));
        
    

可以利用ScriptEngine对js进行执行，然后通过Hutool转为javabean

private static void testJson() throws ScriptException 
        String script = "var json =\\"name\\":\\"admin\\" , \\"mobiTel\\":\\"123\\";" +
                "var result =;result.name=json.name;result.mobiTel=json.mobiTel;JSON.stringify(result);";

        ScriptEngineManager engineManager = new ScriptEngineManager();
        ScriptEngine scriptEngine = engineManager.getEngineByName("JavaScript");
        Object obj = scriptEngine.eval(script);
        User user = JSONUtil.toBean(obj.toString() , User.class);
        System.out.println(user.toString());
    

读取js文件，然后执行js脚本

private static void testJsFile()  
        try (Reader reader= new FileReader(new File(ScriptEngineExample.class.getClassLoader().getResource("test.js").getFile())))
            ScriptEngineManager engineManager = new ScriptEngineManager();
            ScriptEngine scriptEngine = engineManager.getEngineByName("JavaScript");
            scriptEngine.eval(reader);
         catch (FileNotFoundException e) 
            log.error("FileNotFoundException：" , e);
         catch (IOException e) 
            log.error("IOException：" , e);
         catch (ScriptException e)
            log.error("ScriptException：" , e);
        
    

给出一串js，invokeFunction调用js里的函数

private static void testInvokeFunction() throws ScriptException, NoSuchMethodException 
        String script = "var json =\\"name\\":\\"admin\\" , \\"mobiTel\\":\\"123\\";" +
                "function jsonStringify() var result =;result.name=json.name;result.mobiTel=json.mobiTel;print(JSON.stringify(result));";
        ScriptEngineManager engineManager = new ScriptEngineManager();
        ScriptEngine scriptEngine = engineManager.getEngineByName("JavaScript");
        scriptEngine.eval(script);
        Invocable invocable = (Invocable) scriptEngine;
        invocable.invokeFunction("jsonStringify");
    

使用Bindings 传参

private static void testBinding() throws ScriptException, NoSuchMethodException 
       ScriptEngineManager engineManager = new ScriptEngineManager();
       ScriptEngine scriptEngine = engineManager.getEngineByName("JavaScript");
       Bindings bindings = new SimpleBindings();
       bindings.put("username","admin");
       scriptEngine.eval("print('hello , ' + username);" , bindings);