服务端JavaScript之Rhino-白红宇

服务端JavaScript之Rhino

阅读量：6324 次

发布时间：2019-06-22

本文共 8503 字，大约阅读时间需要 28 分钟。

最近在看js的书，书上有介绍两个服务端js,以前只听说过node.js，第一次听说Rhino.js,并且已经集成到了jdk1.6;看来还是见的少啊！

Rhino是一种用Java编写的javaScript解释器，能自动完成JavaScript原生类型到Java原生类型之间的相互转换，有了它，可以通过JavaScript脚本设置。查询Java属性，并调用java方法；

先上学习的代码：

package com.my.rhino;import java.io.FileReader;import java.util.List;import javax.script.Bindings;import javax.script.Compilable;import javax.script.CompiledScript;import javax.script.Invocable;import javax.script.ScriptContext;import javax.script.ScriptEngine;import javax.script.ScriptEngineFactory;import javax.script.ScriptEngineManager;import javax.script.ScriptException;public class RhinoDemo {    public static void main(String[] args) {        // create ScriptEngineManager        ScriptEngineManager manager = new ScriptEngineManager();        ScriptEngine engine = manager.getEngineByName("js");        String script = "print ('hello nm')";        try {            engine.eval(script);            System.out.println();        } catch (ScriptException e) {            e.printStackTrace();        }        try {            Double hour = (Double) engine.eval("var date = new Date(); date.getHours();");            String msg;            if (hour < 10) {                msg = "Good morning";            } else if (hour < 16) {                msg = "Good afternoon";            } else if (hour < 20) {                msg = "Good evening";            } else {                msg = "Good night";            }            System.out.println(hour);            System.out.println(msg);        } catch (ScriptException e) {            System.err.println(e);        }        try {            FileReader reader = new FileReader("src/com/my/rhino/file.js");            Double num = (Double) engine.eval(reader);            System.out.println(num);            reader.close();        } catch (Exception e) {            e.printStackTrace();        }        try {            engine.put("a", 1);            engine.put("b", 5);            Bindings bindings = engine.getBindings(ScriptContext.ENGINE_SCOPE);            Object a = bindings.get("a");            Object b = bindings.get("b");            System.out.println("a = " + a);            System.out.println("b = " + b);            FileReader reader = new FileReader("src/com/my/rhino/vars.js");            Double num = (Double) engine.eval(reader);            System.out.println(num);            reader.close();            reader = new FileReader("src/com/my/rhino/fun.js");            // engine.eval("function add (a, b) {c = a + b; return c; }");            engine.eval(reader);            Invocable jsInvoke = (Invocable) engine;            Object result1 = jsInvoke.invokeFunction("add", new Object[] { 10, 5 });            System.out.println(result1);            Adder adder = jsInvoke.getInterface(Adder.class);            int result2 = adder.add(10, 5);            System.out.println(result2);            Compilable jsCompile = (Compilable) engine;            CompiledScript vscript = jsCompile.compile("function hi () {print ('ddddd !'); }; hi ();");            for (int i = 0; i < 5; i++) {                vscript.eval();            }        } catch (Exception e) {            // TODO: handle exception        }        try {            FileReader reader = new FileReader("src/com/my/rhino/java.js");            @SuppressWarnings("unchecked")            List
      
        num = (List
       
        ) engine.eval(reader);            System.out.println();            for (String word : num) {                System.out.print(word);            }            reader.close();        } catch (Exception e) {            e.printStackTrace();        }        List
        
          factoryList = manager.getEngineFactories();        for (ScriptEngineFactory factory : factoryList) {            System.out.println("=====");            System.out.println(factory.getEngineName());            System.out.println(factory.getEngineVersion());            System.out.println(factory.getLanguageName());            System.out.println(factory.getLanguageVersion());            System.out.println(factory.getExtensions());            System.out.println(factory.getMimeTypes());            System.out.println(factory.getNames());        }    }}

Rhino.java

下面解析下：

1、创建一个script 引擎管理器并根据名称获取需要的js引擎；以下所有操作基于这两行代码；

// create ScriptEngineManager

ScriptEngineManager manager = new ScriptEngineManager();

// create a JavaScript engine

ScriptEngine engine = manager.getEngineByName("js");

引擎也许不止一个，可以通过以下代码输出查看；

List
     
       factoryList = manager.getEngineFactories();        for (ScriptEngineFactory factory : factoryList) {            System.out.println("=====");            System.out.println(factory.getEngineName());            System.out.println(factory.getEngineVersion());            System.out.println(factory.getLanguageName());            System.out.println(factory.getLanguageVersion());            System.out.println(factory.getExtensions());            System.out.println(factory.getMimeTypes());            System.out.println(factory.getNames());        }

获取支持的所有引擎的详细信息；我的机器输出如下：

Mozilla Rhino

1.7 release 3 PRERELEASE

ECMAScript

1.8

[js]

[application/javascript, application/ecmascript, text/javascript, text/ecmascript]

[js, rhino, JavaScript, javascript, ECMAScript, ecmascript]

2、简单输出字符串：

String script = "print ('hello nm')";        try {            engine.eval(script);            System.out.println();        } catch (ScriptException e) {            e.printStackTrace();        } console:  hello nm

3、执行简单的js代码获取返回值：

try {            Double hour = (Double) engine.eval("var date = new Date(); date.getHours();");            System.out.println(hour);        } catch (ScriptException e) {            System.err.println(e);        } console输出当前时间的小时数：  //13.0

4、执行js文件里面的语句，并获取返回值：

//java代码：  try {            FileReader reader = new FileReader("src/com/my/rhino/file.js");            Double num = (Double) engine.eval(reader);            System.out.println(num);            reader.close();        } catch (Exception e) {            e.printStackTrace();        } console ---> 18.0

//file.js function add(a,b){    return a+b;}//add(10,8);  result = add(10,8);//以上两行语句皆可实现

5、传递变量给js文件并执行js文件代码：

//java代码　　　　　　　engine.put("a", 1);            engine.put("b", 5);            Bindings bindings = engine.getBindings(ScriptContext.ENGINE_SCOPE);            Object a = bindings.get("a");            Object b = bindings.get("b");            System.out.println("a = " + a);            System.out.println("b = " + b);            FileReader reader = new FileReader("src/com/my/rhino/vars.js");            Double num = (Double) engine.eval(reader);            System.out.println(num);            reader.close();

//vars.js m = a+5;n = b+6;d = a+b;

console---> 6.0 //只会返回最后一行的结果值

6、java调用js中的方法：

reader = new FileReader("src/com/my/rhino/file.js");            // engine.eval("function add (a, b) {c = a + b; return c; }");            engine.eval(reader);            Invocable jsInvoke = (Invocable) engine;            Object result1 = jsInvoke.invokeFunction("add", new Object[] { 10, 5 });            System.out.println(result1);　　　　　　  //动态实现接口，从脚本引擎中得到Java Interface 的实例；也就是说，可以定义个一个Java接口，其实现是由脚本完成,函数名称必须相同；            Adder adder = jsInvoke.getInterface(Adder.class);            int result2 = adder.add(10, 5);            System.out.println(result2);

package com.my.rhino;interface Adder {  int add(int a, int b);}

console----->

15.0 15

7、编译执行

　　脚本引擎默认是解释执行的，如果需要反复执行脚本，可以使用它的可选接口Compilable来编译执行脚本，以获得更好的性能，示例代码如下：

Compilable jsCompile = (Compilable) engine;            CompiledScript vscript = jsCompile.compile("function hi () {print ('ddddd !'); }; hi ();");            for (int i = 0; i < 5; i++) {                vscript.eval();            }//其中js代码可以从js文件中加载

8、使用java中的对象：

try {            FileReader reader = new FileReader("src/com/my/rhino/java.js");            @SuppressWarnings("unchecked")            List
      
        num = (List
       
        ) engine.eval(reader);            System.out.println();            for (String word : num) {                System.out.print(word);            }            reader.close();        } catch (Exception e) {            e.printStackTrace();        }

//java.js importPackage(java.util);//var list = java.util.ArrayList();var list = ArrayList();list.add('ni');list.add(' zai');list.add(' zuo');list.add(' sha');list;//var list = java.util.ArrayList();等价于importPackage(java.util); var list = ArrayList();

9、总结：

这都是很基本的，高级应用还需研究！

转载于:https://www.cnblogs.com/liangblog/p/5956256.html

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