带有QtAndroidExtras的Java代码

Question

PowerManager powerManager = (PowerManager) getSystemService(POWER_SERVICE);

我想通过JNI(使用QtAndroidExtras(在C++中实现它，但我不明白(PowerManager)的代码是做什么的。

这是类型转换吗？我想知道是否可以用QtAndroidExtras实现它，而不必编写java类。

Answer 1

PowerManager是Android SDK的一个Java类。这是它的文档。

下面是如何通过 QAndroidJniObject 使用PowerManager的示例。

爪哇代码：

PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "My Tag");
wl.acquire();

等效的Qt代码：

QAndroidJniObject activity = QAndroidJniObject::callStaticObjectMethod("org/qtproject/qt5/android/QtNative", "activity", "()Landroid/app/Activity;");
if ( activity.isValid() )
{
    QAndroidJniObject serviceName = QAndroidJniObject::getStaticObjectField<jstring>("android/content/Context","POWER_SERVICE");
    if ( serviceName.isValid() )
    {
        QAndroidJniObject powerMgr = activity.callObjectMethod("getSystemService", "(Ljava/lang/String;)Ljava/lang/Object;",serviceName.object<jobject>());
        if ( powerMgr.isValid() )
        {
            jint levelAndFlags = QAndroidJniObject::getStaticField<jint>("android/os/PowerManager","SCREEN_DIM_WAKE_LOCK");
            QAndroidJniObject tag = QAndroidJniObject::fromString( "My Tag" );
            QAndroidJniObject wakeLock = powerMgr.callObjectMethod("newWakeLock", "(ILjava/lang/String;)Landroid/os/PowerManager$WakeLock;", levelAndFlags,tag.object<jstring>());
            if ( wakeLock.isValid() )
            {
                wakeLock.callMethod<void>("acquire", "()V");
                qDebug() << "Acquired lock!";
            }
        }
    }
}