Spring boot integrated GraalVM JS engine quick start demo

HBLOG

2 min readMar 8, 2024

一、GraalVM.js introduction

Is a JavaScript interpreter/compiler capable of running Node.js applications on the JVM;

Main application scenarios

Dynamically change program execution logic through JS, such as: risk control rules, service orchestration, etc.

二、Code Project

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springboot-demo</artifactId>
        <groupId>com.et</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
   <artifactId>graalvm-js</artifactId>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.graalvm.js</groupId>
            <artifactId>js-scriptengine</artifactId>
            <version>20.2.0</version>
        </dependency>
        <dependency>
            <groupId>org.graalvm.js</groupId>
            <artifactId>js</artifactId>
            <version>20.2.0</version>
        </dependency>
    </dependencies>
</project>

Application.yaml

server:
  port: 8088

Main class

package com.et.graalvm.js;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class DemoApplication {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}

Code repository

https://github.com/Harries/springboot-demo

三、Test

local invoke

package com.et.graalvm.js;
import org.junit.Test;
import javax.script.*;
/**
 * @author liuhaihua
 * @version 1.0
 * @ClassName com.et.graalvm.js.JSTest
 * @Description todo
 * @date 2024/03/07 9:47
 */
public class JSTest {
    @Test
    public  void test10(){
        // create JavaScript engine
        ScriptEngine jsEngine = new ScriptEngineManager().getEngineByName("js");
//        ScriptEngine jsEngine = new ScriptEngineManager().getEngineByExtension("js");
//        ScriptEngine jsEngine = new ScriptEngineManager().getEngineByMimeType("text/javascript");
        // method 1，set variables
        jsEngine.put("hello", "jack");
        // method 2，use binding to set variables
        SimpleBindings bindings = new SimpleBindings();
        bindings.put("hello","world");
        jsEngine.setBindings(bindings, ScriptContext.GLOBAL_SCOPE);
        // method 3，use Context to set variables
        ScriptContext scriptContext = jsEngine.getContext();
        scriptContext.setAttribute("hello", "polo", ScriptContext.ENGINE_SCOPE);
        try {
            // method 1，directly call
            jsEngine.eval("print(hello)");
            // method 2，Compile and call (needs to be called repeatedly, it is recommended to compile first and then call)
            if (jsEngine instanceof Compilable){
                CompiledScript compileScript = ((Compilable) jsEngine).compile("print(hello)");
                if (compileScript != null){
                    for (int i = 0; i < 10; i++) {
                        compileScript.eval();
                    }
                }
            }
            Invocable invocable = ((Invocable)jsEngine);
            // Method 3, use top-level methods in JavaScript
            jsEngine.eval("function greet(name) { print('Hello, ' + name); } ");
            invocable.invokeFunction("greet", "tom");
            // Method 4, using a method of an object
            jsEngine.eval("var obj = { getGreeting: function(name){ return 'hello, ' + name; } } ");
            Object obj = jsEngine.get("obj");
            Object result = invocable.invokeMethod(obj, "getGreeting", "kitty");
            System.out.println(result);
        } catch (ScriptException | NoSuchMethodException e) {
            e.printStackTrace();
        }
    }
}

remote invoke

package com.et.graalvm.js;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
public class RemoteJSTest {
    public static void main(String[] args) throws IOException, ScriptException {
        URL jsUrl = new URL("https://example.com/script.js"); 
        URLConnection connection = jsUrl.openConnection();
        InputStream inputStream = connection.getInputStream(); 
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        StringBuilder sb = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            sb.append(line).append("\n"); 
        }
        reader.close();
        inputStream.close();
        ScriptEngineManager engineManager = new ScriptEngineManager();
        ScriptEngine engine = engineManager.getEngineByName("nashorn"); 
        String script = sb.toString(); 
        engine.eval(script); 
        Object result = engine.eval("hello()"); 
        System.out.println(result); 
    }
}