graalvm 對於js 的處理也是支援Promise 的，但是我們的java 物件需要實現PromiseExecutor 介面

介面定義

這個是官方文件的說明，但是實際沒找到，變通方法可以通過BiConsumer 解決

@FunctionalInterface

public interface PromiseExecutor {

  void onPromiseCreation(Value onResolve, Value onReject);

}

參考使用

• MyLogin.java

public class MyLogin implements BiConsumer<Value, Value> {
 

  @Override

  public void accept(Value resolve, Value reject) {

    resolve.execute("OK");

   }

  public String logintoken(String username,String password) {

    return String.format("%s------%s",username,password);

   }

}

• js 程式碼

function mylogin(){

  var BigDec = Java.type('java.math.BigDecimal');
 

  var bd = new BigDec("0.1");

  var login = Java.type("MyLogin")

  console.dir(login);

  var applogin = new login()

  console.dir(applogin);

  console.log(applogin.logintoken("dalong","demoapp"))

  new Promise(applogin).then((data)=>{

    console.log(data)

   }).catch((err)=>{
 

    console.log(err)

   })

  console.log(bd.add(bd).toString());

  return "dalong rong feng"

}

• 程式碼呼叫

Engine engine = Engine.newBuilder().option("js.load-from-url","true").allowExperimentalOptions(true).build();

public static void loadURL(Engine engine) throws IOException {

    Context context = Context.newBuilder().allowAllAccess(true).allowHostClassLoading(true).allowIO(true).engine(engine).build();

    Source mysource =Source.newBuilder("js"," load(\"http://127.0.0.1:8080/mylogin.js\")","rongdemo").build();

    context.eval(mysource);

    Value callapp = context.getBindings("js").getMember("mylogin");

    System.out.println(callapp.execute());

}

• 執行效果

參考資料

https://github.com/graalvm/graaljs/blob/master/docs/user/JavaScriptCompatibility.md
https://github.com/graalvm/graaljs/issues/106