javascript脚本怎么运行（js脚本编写教程）

1 概述

本文介绍在 Java 环境中执行 JavaScript 脚本的简单使用，具体包含以下内容

1. Java 8 中的内置 Nashorn Javascript 引擎介绍
2. Rhino JavaScript 引擎介绍以及对 XML 的处理介绍

2 Java 8 中的内置 Nashorn Javascript 引擎介绍

Nashorn 是 Java 8 中内置的 JavaScript 引擎，无需加入任何依赖。

Nashorn 基本使用步骤如下

1. new 出 ScriptEngineManager 对象
2. 通过 ScriptEngineManager 对象中的 getEngineByName 方法获取指定的 JavaScript 引擎，返回 ScriptEngine 对象
3. Java 8 中的默认的 Javascript 引擎包括：[nashorn, Nashorn, js, JS, JavaScript, javascript, ECMAScript, ecmascript]
4. 通过 ScriptEngine 对象的 eval 方法来执行 JavaScript 脚本。

2.1 通过 PrintWriter 对象获取脚本中的 print 输出

Javascript 脚本中没有函数，没有返回值，通过 print 输出内容，这时需要通过 PrintWriter 获取读取脚本中的 print 输出，具体如下

@Test    public void test_nashorn() {        try {            ScriptEngine engine = new ScriptEngineManager().getEngineByName("Nashorn");            ScriptContext scriptContext = engine.getContext();            StringWriter stringWriter = new StringWriter();            PrintWriter printWriter = new PrintWriter(stringWriter);            scriptContext.setWriter(printWriter);            String jsString = "var obj=JSON.parse('{\\\"data\\\":\\\"7155\\\",\\\"sign\\\":\\\"success\\\",\\\"message\\\":null}');print(obj.sign==\"success\");";            stringWriter = new StringWriter();            printWriter = new PrintWriter(stringWriter);            scriptContext.setWriter(printWriter);            engine.eval(jsString);            System.out.println(String.format("1 result = %s",stringWriter.toString()));            jsString = "var obj=JSON.parse('{\\\"data\\\":\\\"7157\\\",\\\"sign\\\":\\\"success\\\",\\\"message\\\":null}');print((function getData() {  return obj.data;})())";            stringWriter = new StringWriter();            printWriter = new PrintWriter(stringWriter);            scriptContext.setWriter(printWriter);            engine.eval(jsString);            System.out.println(String.format("2 result = %s",stringWriter.toString()));            jsString = "var obj=JSON.parse('{\\\"data\\\":\\\"7157\\\",\\\"sign\\\":\\\"success\\\",\\\"message\\\":null}');print((function getData() {  return obj.data;})())";            stringWriter = new StringWriter();            printWriter = new PrintWriter(stringWriter);            scriptContext.setWriter(printWriter);            engine.eval(jsString);            System.out.println(String.format("3 result = %s",stringWriter.toString()));        } catch (Exception e) {            e.printStackTrace();        }    }

2.2 获取匿名函数的返回值

Javascript 脚本是一个匿名函数并且有返回值，通过 eval 函数可以直接

@Testpublic void test_js_function_return() {    try {        ScriptEngine engine = new ScriptEngineManager().getEngineByName("Nashorn");        String jsFunction = "(function(){var obj=JSON.parse('{\\\"data\\\":\\\"7155\\\",\\\"sign\\\":\\\"success\\\",\\\"message\\\":null}');return obj.sign==\"success\"})();";        Boolean result = (Boolean) engine.eval(jsFunction);        System.out.println(result);    } catch (Exception e) {        e.printStackTrace();    }}

2.3 调用 Javascript 脚本中指定的函数

Javascript 脚本中有变量，有多个函数，具体如下

@Testpublic void test_invoke_js_function() {    try {        ScriptEngine engine = new ScriptEngineManager().getEngineByName("Nashorn");        /*        var obj = JSON.parse('{\"data\":\"7155\",\"sign\":\"success\",\"message\":null}');        function checkSign() {            return obj.sign == 'success'        }        function getData() {            return obj.data        }        function calculate(a, b) {            return a + b        }         */        String jsFunction = "var obj=JSON.parse('{\\\"data\\\":\\\"7155\\\",\\\"sign\\\":\\\"success\\\",\\\"message\\\":null}');function checkSign(){return obj.sign=='success'}function getData(){return obj.data}function calculate(a,b){return a+b}";        engine.eval(jsFunction);        Invocable invocable = (Invocable) engine;        Object result = invocable.invokeFunction("checkSign", null);        System.out.println(result);        result = invocable.invokeFunction("getData", null);        System.out.println(result);        result = invocable.invokeFunction("calculate", 2, 5);        System.out.println(result);    } catch (Exception e) {        e.printStackTrace();    }}

• 输出如下

true71557.0

2.4 读取 Javascript 文件并执行

这种情况是读取 Javascript 文件，并执行，具体如下

• src/test/resources/test.js

@Testpublic void test_invoke_js_file() {    try {        ScriptEngine engine = new ScriptEngineManager().getEngineByName("Nashorn");        engine.eval(new FileReader(TestJSEngine.class.getResource("/test.js").getPath()));        Invocable invocable = (Invocable) engine;        Object result = invocable.invokeFunction("checkSign", null);        System.out.println(result);        result = invocable.invokeFunction("getData", null);        System.out.println(result);        result = invocable.invokeFunction("calculate", 2, 5);        System.out.println(result);    } catch (Exception e) {        e.printStackTrace();    }}

文件内容和上面一样。

3 Rhino JavaScript 引擎介绍

默认的 Nashorn 引擎是无法解析 xml 的，像 DOMParser 这样的对象是浏览器内置的组件。

这里可以通过 Maven 依赖 Rhino 引擎来处理 xml。

• Rhino Maven 依赖如下

<dependency>  <groupId>cat.inspiracio</groupId>  <artifactId>rhino-js-engine</artifactId>  <version>1.7.10</version></dependency>

使用的步骤和其他 JavaScript 引擎一样，引擎的名称为 Rhino.

3.1 Rhino 对 xml 的解析

这里通过读取文件的方式来加载和解析 JavaScript 脚本，脚本中是对一段 xml 的解析的过程。

• src/test/resources/xml.js 文件内容如下

print("----------------------------------------");var e = new XML('<employees> <employee id="1"><name>Joe</name><age>20</age></employee> <employee id="2"><name>Sue</name><age>30</age></employee>  </employees>');// 获取所有的员工print("获取所有的员工:\n" + e..name);// 名字叫 Joe 的员工print("名字叫 Joe 的员工:\n" + e.employee.(name == "Joe"));// 员工的id 为 1 和 2print("员工的id 为 1 和 2:\n" + e.employee.(@id == 1 || @id == 2));// 员工的id 为 1print("员工的id 为 1: " + e.employee.(@id == 1).name);print("----------------------------------------");

• 执行如下

@Testpublic void test_rhino_file_js() {    try {        ScriptEngine engine = new ScriptEngineManager().getEngineByName("rhino");        ScriptContext scriptContext = engine.getContext();        StringWriter stringWriter = new StringWriter();        PrintWriter printWriter = new PrintWriter(stringWriter);        scriptContext.setWriter(printWriter);        engine.eval(new FileReader(TestJSEngine.class.getResource("/xml.js").getPath()));        System.out.println(String.format("xml result = %s",stringWriter.toString() ));    } catch (Exception e) {        e.printStackTrace();    }}

• 输出如下

xml result = ----------------------------------------All the employee names are:<name>Joe</name><name>Sue</name>The employee named Joe is:<employee id="1">  <name>Joe</name>  <age>20</age></employee>Employees with ids 1 & 2:<employee id="1">  <name>Joe</name>  <age>20</age></employee><employee id="2">  <name>Sue</name>  <age>30</age></employee>Name of the the employee with ID=1: Joe----------------------------------------

3.2 测试

• xml 内容如下

<CCardProcessSyncResponse>    <RetCode>0</RetCode>    <Message>操作成功！</Message>    <RefundCycle />    <EpayRefundCycleMin>1</EpayRefundCycleMin>    <EpayRefundCycleMax>7</EpayRefundCycleMax>    <EpayRefundCycleUnitF /></CCardProcessSyncResponse>

• 具体测试如下

@Testpublic void test_rhino() {    try {        ScriptEngine engine = new ScriptEngineManager().getEngineByName("rhino");        String jsString = jsString = "var obj=new XML('<CCardProcessSyncResponse>    <RetCode>0</RetCode>    <Message>操作成功！</Message>    <RefundCycle />    <EpayRefundCycleMin>1</EpayRefundCycleMin>    <EpayRefundCycleMax>7</EpayRefundCycleMax>    <EpayRefundCycleUnitF />  </CCardProcessSyncResponse>');print(obj.Message == '操作成功！');";        ScriptContext scriptContext = engine.getContext();        StringWriter stringWriter = new StringWriter();        PrintWriter printWriter = new PrintWriter(stringWriter);        scriptContext.setWriter(printWriter);        engine.eval(jsString);        System.out.println(String.format("xml result = %s",stringWriter.toString() ));    } catch (Exception e) {        e.printStackTrace();    }}

上面的输出结果如下

xml result = true