Image{
  source: "file:///mnt/usbhost1/Config/logo.png"
}

QQuickView view;
view.setSource(QUrl(QStringLiteral("qrc:///qml/MainView.qml")));
QObject *qmlObj =(QObject*) view.rootObject();
MainWnd *w=new MainWnd(object);
//暴露C++类给qml供其调用，别名mainWndClass
view.engine ()->rootContext ()->setContextProperty (QLatin1String("mainWndClass"),w);

//c++调用qml中的js方法
//参数必须转换为QVariant
QMetaObject::invokeMethod (qmlObj,"showRight",Q_ARG(QVariant,1));
//调用子项的js方法
qmlPlayer = qmlObj->findChild<QObject*>("playerArea");
QMetaObject::invokeMethod (qmlPlayer,"setVideoFile",Q_ARG(QVariant,currentVideoFile));

//MainView.qml
Rectangle {
  anchors.fill: parent
  property int leftAreaWidth: this.width/5*4
  property int rightAreaWidth: this.width/5
  property int queueFontSize
  function showRight(isShow){
    ....
  }
  Player{
    id:playerArea
    //设置objectName，在c++中才能找到它
    objectName: "playerArea"
    width: parent.width
    height: parent.height
  }
}

org\rophie\ProjectName即为java类的包名package org.rophie.ProjectName;

package org.rophie.ProjectName;
import org.qtproject.qt5.android.bindings.QtActivity;
import android.widget.Toast;
import android.media.AudioManager;
import android.content.Context;
public class JavaClass extends QtActivity{
  private static JavaClass m_instance;
  private static AudioManager mAudioManager;
  public JavaClass()
  {
    //构造函数必须
    m_instance = this;
  }
   public static void setVolume(int vol){
   if(mAudioManager==null){
     mAudioManager = (AudioManager)m_instance.getSystemService(Context.AUDIO_SERVICE);
   }
     mAudioManager.setStreamVolume(AudioManager.STREAM_MUSIC, vol, 0);
   }
}

QAndroidJniObject::callStaticMethod<void>("org/rophie/ProjectName/JavaClass","setVolume","(I)V",3);

 
//具体参照QAndroidJniObject类

public void onReceive(Context context, Intent intent) {
 ......
 //JavaClass为继承QtActivity的java主类
 Intent intent2 = new Intent(context, JavaClass.class);
 ......
}