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

java 8 中的内置 nashorn javascript 引擎介绍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

new 出 scriptenginemanager 对象通过 scriptenginemanager 对象中的 getenginebyname 方法获取指定的 javascript 引擎，返回 scriptengine 对象java 8 中的职场潜规则默认的 javascript 引擎包括：[nashorn, nashorn, js, js, javascript, javascript, ecmascript, ecmascript]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.twriter(printwriter);            string jsstring = "var obj=json.par('{\\\"data\\\":\\\"7155\\\",\\\"sign\\\":\\\"success\\\",\\\"message\\\":null}');print(obj.sign==\"success\");";            stringwriter = new stringwriter();            printwriter = new printwriter(stringwriter);            scriptcontext.twriter(printwriter);            engine.eval(jsstring);            system.out.println(string.format("1 result = %s",stringwriter.tostring()));            jsstring = "var obj=json.par('{\\\"data\\\":\\\"7157\\\",\\\"sign\\\":\\\"success\\\",\\\"message\\\":null}');print((function getdata() {  return obj.data;})())";            stringwriter = new stringwriter();            printwriter = new printwriter(stringwriter);            scriptcontext.twriter(printwriter);            engine.eval(jsstring);            system.out.println(string.format("2 result = %s",stringwriter.tostring()));            jsstring = "var obj=json.par('{\\\"data\\\":\\\"7157\\\",\\\"sign\\\":\\\"success\\\",\\\"message\\\":null}');print((function getdata() {  return obj.data;})())";            stringwriter = new stringwriter();            printwriter = new printwriter(stringwriter);            scriptcontext.twriter(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.par('{\\\"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.par('{\"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.par('{\\\"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();  理论经济学  }}

输出如下

true71557.0

2.4 读取 javascript 文件并执行

这种情况是读取 ja世界上最难的语言vascript 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(testjngine.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 domparr 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();    温州职业技术学校    printwriter printwriter = new printwriter(stringwriter);        scriptcontext.twriter(printwriter);        engine.eval(new filereader(testjngine.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

<ccardprocesssyncrespon>    <retcode>0</retcode>    <message>操作成功！</message>    <refundcycle />    <epayrefundcyclemin>1</epayrefundcyclemin>    <epayrefundcyclemax>7</epayrefundcyclemax>    <epayrefundcycleunitf /></ccardprocesssyncrespon>

具体测试如下

@testpublic void test_rhino() {    try {        scriptengine engine = new scriptenginemanager().getenginebyname("rhino");        string jsstring = jsstring = "var obj=new xml('<ccardprocesssyncrespon>    <retcode>0</retcode>    <message>操作成功！</message>    <refundcycle />    <epayrefundcyclemin>1</epayrefundcyclemin>    <epayrefundcyclemax>7</epayrefundcyclemax>    <epayrefundcycleunitf />  </ccardprocesssyncrespon>');print(obj.message == '操作成功！');";        scriptcontext scriptcontext = engine.getcontext();        stringwriter stringwriter = new stringwriter();        printwriter printwriter = new printwriter(stringwriter);        嘴巴scriptcontext.twriter(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