Java中运行javascript代码(二)

青旅半醒 2024-04-18 15:12 54阅读 0赞

本文在《Java中运行javascript代码(一)》基础上，展示了如何通过java向js函数传递参数。 请先阅读[《Java中运行javascript代码(一)》][Java_javascript]以便您更快理解例子。

本文将展示两个示例。

第一个示例，通过java将json对象传递给js函数

第二个示例， 将数组传递给js函数，js需要将其中个别位置的字节数组组合后再转回为10进制。  
例如，将数组第5和6位，转变为数字， 0xa1, 0x9F, 也就是线组成a19f,然后转换41375。

# Java 代码 #

package com.yq.jsdemo;
    
    
    import com.alibaba.fastjson.JSONObject;
    import lombok.extern.slf4j.Slf4j;
    
    import javax.script.Invocable;
    import javax.script.ScriptEngine;
    import javax.script.ScriptEngineManager;
    import java.io.File;
    import java.io.Reader;
    import java.nio.charset.Charset;
    import java.nio.file.Files;
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.List;
    
    
    /** * Simple to Introduction * className: JavaJSDemo * * @author EricYang * @version 2018/12/22 9:51 */
    
    @Slf4j
    public class JavaJSListDemo { 
    
        private static final String JS_ENGINE_NAME= "nashorn";
        private final ScriptEngineManager sem = new ScriptEngineManager();
        private final ScriptEngine engine = sem.getEngineByName(JS_ENGINE_NAME);
    
        public static void main(String[] args) { 
            JavaJSListDemo demo = new JavaJSListDemo();
    
            demo.invokeFunctionByFileWithParams();
            demo.invokeFunctionByFileWithListParams();
        }
    
        private void invokeFunctionByFileWithParams() { 
            log.info("--- invokeFunctionWithParams ---" );
            try { 
                log.info("Current dir={}", System.getProperty("user.dir"));
                File file = new File("./javademo/src/main/resources/demoWithParams.js");
                Reader reader = Files.newBufferedReader(file.toPath(), Charset.defaultCharset());
    
                Object obj1 = engine.eval(reader);
    
                Invocable jsInvoke = (Invocable) engine;
                JSONObject user = new JSONObject();
                user.put("name", "张三");
                user.put("age", 18);
                //js函数的就是去user对象age然后加上3
                Object obj2 = jsInvoke.invokeFunction("myFunc", user,3);
    
                log.info("function={}, result={}", obj1, obj2);
            }
            catch(Exception ex) { 
                log.warn("exception", ex);
            }
        }
    
        private void invokeFunctionByFileWithListParams() { 
            log.info("--- With List Params ---" );
            try { 
                log.info("Current dir={}", System.getProperty("user.dir"));
                File file = new File("./javademo/src/main/resources/demoWithListParams.js");
                Reader reader = Files.newBufferedReader(file.toPath(), Charset.defaultCharset());
    
                Object obj1 = engine.eval(reader);
    
                Invocable jsInvoke = (Invocable) engine;
                List<Short> dataList = new ArrayList<>();
                //15,01,00,00,00,0x0B,01,03,08,01,83,0x63,0x88,02,03,0xEA,0x1B
                dataList.add((short)0x15);
                dataList.add((short)0x01);
                dataList.add((short)0x00);
                dataList.add((short)0x00);
                dataList.add((short)0x00);
                dataList.add((short)0x0B);
                dataList.add((short)0x01);
                dataList.add((short)0x03);
                dataList.add((short)0x08);
    
                dataList.add((short)0x01);
                dataList.add((short)0x83);
                dataList.add((short)0x63);
                dataList.add((short)0x88);
    
    
                dataList.add((short)0x02);
                dataList.add((short)0x03);
                dataList.add((short)0xEA);
                dataList.add((short)0x1B);
    
                Object obj2 = jsInvoke.invokeFunction("myFunc", Arrays.toString(dataList.toArray()), "device1234");
    
                log.info("function={}", obj1);
                log.info("result={}", obj2);
            }
            catch(Exception ex) { 
                log.warn("exception", ex);
            }
        }
    }

# JS代码 #

## demoWithParams.js ##

传入的user是个json对象， 将user的age属性加上inc然后返回

function myFunc( user, inc) { 
       return user.age + inc ;
    }

## demoWithListParams.js ##

传入的对象是个数组， 类似"\[0x83,0x63,0x88,0x02,0x03,0xEA,0x1B\]"

[Java_javascript]: https://blog.csdn.net/russle/article/details/85214044