public class RNTestModule extends ReactContextBaseJavaModule{
  public RNTestModule(ReactApplicationContext reactContext) {
    super(reactContext);
  }
  @Override
  public String getName() {
    return "RNTest";
  }

 @ReactMethod
 public void measureLayout(
   int tag,
   int ancestorTag,
   Callback errorCallback,
   Callback successCallback) {
  try {
   measureLayout(tag, ancestorTag, mMeasureBuffer);
   map.putDouble("relativeX",1);
   map.putDouble("relativeY", 1);
   map.putDouble("width", 2);
   map.putDouble("height",3);
   successCallback.invoke(relativeX, relativeY, width, height);
  } catch (IllegalViewOperationException e) {
   errorCallback.invoke(e.getMessage());   
  }
}

RNTest.measureLayout(
 100,
 100,
 (msg) => {
  console.log(msg);
 },
 (x, y, width, height) => {
  console.log(x + ':' + y + ':' + width + ':' + height);
 }
);

public class RNTestModule extends ReactContextBaseJavaModule{
  public RNTestModule(ReactApplicationContext reactContext) {
    super(reactContext);
  }
  @Override
  public String getName() {
    return "RNTest";
  }
  @ReactMethod
  public void measureLayout(
      int tag,
      int ancestorTag,
      Promise promise) {
    try {
      WritableMap map = Arguments.createMap();
      map.putDouble("relativeX",1);
      map.putDouble("relativeY", 1);
      map.putDouble("width", 2);
      map.putDouble("height",3);

      promise.resolve(map);
    } catch (IllegalViewOperationException e) {
      promise.reject(e);
    }
  }
}

async test() {
 try {
  var {
    relativeX,
    relativeY,
    width,
    height,
  } = await RNTest.measureLayout(100, 100);

  console.log(relativeX + ':' + relativeY + ':' + width + ':' + height); 
 } catch (e) {
  console.error(e);
 }
}

test2(){
 RNTest.measureLayout(100,100).then(e=>{
  console.log(e.relativeX + ':' + e.relativeY + ':' + e.width + ':' + e.height);
  this.setState({
   relativeX:e.relativeX,
   relativeY:e.relativeY,
   width:e.width,
   height:e.height,
  })
 }).catch(error=>{
  console.log(error);
 });
}

@Override
public void onHandleResult(String barcodeData) {
  WritableMap params = Arguments.createMap();
  params.putString("result", barcodeData);
  sendEvent(getReactApplicationContext(), "onScanningResult", params);
}

private void sendEvent(ReactContext reactContext,String eventName, @Nullable WritableMap params) {
  reactContext.getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class)
      .emit(eventName, params);
}

componentDidMount() {
  //注册扫描监听
  DeviceEventEmitter.addListener('onScanningResult',this.onScanningResult);
}
onScanningResult = (e)=> {
  this.setState({
    scanningResult: e.result,
  });
  // DeviceEventEmitter.removeListener('onScanningResult',this.onScanningResult);//移除扫描监听
}