Eskil Abrahamsen Blomfeldt在他的博客上有一篇文章,展示了如何从C++ here调用QtActivity /(HangmanActivity)静态Java方法。
他提到他只使用静态方法,因为这样做更容易(实际上),并且在他的示例中仅此而已。引用:
调用静态方法有效。调用非静态方法不起作用(从不输入功能)。如果我在onCreate()中调用非静态方法connectBluetooth(),则它可以工作。有没有办法可以在onCreate()中调用而不使用非静态方法?
编辑:
我想我将添加一些代码。我扩展了QtActivity类:
package org.qtproject.qt5.android.bindings;
import org.qtproject.qt5.android.bindings.QtApplication;
import org.qtproject.qt5.android.bindings.QtActivity;
import android.bluetooth.BluetoothAdapter;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import java.lang.String;
public class MyActivity extends QtActivity
{
private BluetoothAdapter bluetoothAdapter;
private static final int ENABLE_BLUETOOTH_REQUEST = 1;
public MyActivity()
{
Log.d(QtApplication.QtTAG, "MyActivity constructor called");
}
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
}
@Override
public void onDestroy()
{
super.onDestroy();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
Log.d(QtApplication.QtTAG, "onActivityResult entered");
if(requestCode == 1)
{
if(requestCode == 1)
{
if(resultCode == RESULT_OK)
{
Log.d(QtApplication.QtTAG, "User accepted to enable Bluetooth");
}
else if(resultCode == RESULT_CANCELED)
{
Log.d(QtApplication.QtTAG, "User declined to enable Bluetooth");
}
}
}
}
public void connectBluetooth()
{
Log.d(QtApplication.QtTAG, "connectBluetooth() entered");
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(bluetoothAdapter == null)
{
Log.d(QtApplication.QtTAG, "Bluetooth adapter is not found");
return;
}
if(!bluetoothAdapter.isEnabled())
{
Log.d(QtApplication.QtTAG, "Bluetooth is off");
Intent enableBluetoothIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBluetoothIntent, ENABLE_BLUETOOTH_REQUEST);
}
}
public static void test()
{
Log.d(QtApplication.QtTAG, "Static Test OK!");
}
}
我尝试从此C++类调用这些方法:
#include "bluetooth.h"
#include <QtAndroidExtras>
#include <QDebug>
Bluetooth::Bluetooth(QObject *parent) :
QObject(parent)
{
}
void Bluetooth::connect()
{
//Test static call
QAndroidJniObject::callStaticMethod<void>("org/qtproject/qt5/android/bindings/MyActivity", "test");
//Test non-static call
//Line below creates a new object and is a subclass of QtActivity.
bluetooth = new QAndroidJniObject("org/qtproject/qt5/android/bindings/MyActivity");
if(!bluetooth->isValid())
{
qDebug() << "bluetooth is an invalid java object";
return;
}
bluetooth->callMethod<void>("connectBluetooth");
}
编辑:
我最不确定的程序部分是AndroidManifest.xml。也许有些东西可以解释这种行为?
<?xml version='1.0' encoding='utf-8'?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" package="org.qtproject.example.AndroidTest" android:versionName="1.0" android:installLocation="auto">
<application android:label="@string/app_name" android:name="org.qtproject.qt5.android.bindings.QtApplication">
<activity android:configChanges="orientation|uiMode|screenLayout|screenSize|smallestScreenSize|locale|fontScale|keyboard|keyboardHidden|navigation" android:label="@string/app_name" android:name="org.qtproject.qt5.android.bindings.MyActivity" android:screenOrientation="unspecified">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
<meta-data android:value="AndroidTest" android:name="android.app.lib_name"/>
<meta-data android:resource="@array/qt_sources" android:name="android.app.qt_sources_resource_id"/>
<meta-data android:value="default" android:name="android.app.repository"/>
<meta-data android:resource="@array/qt_libs" android:name="android.app.qt_libs_resource_id"/>
<meta-data android:resource="@array/bundled_libs" android:name="android.app.bundled_libs_resource_id"/>
<!-- Deploy Qt libs as part of package -->
<meta-data android:value="1" android:name="android.app.bundle_local_qt_libs"/>
<meta-data android:resource="@array/bundled_in_lib" android:name="android.app.bundled_in_lib_resource_id"/>
<meta-data android:resource="@array/bundled_in_assets" android:name="android.app.bundled_in_assets_resource_id"/>
<!-- Run with local libs -->
<meta-data android:value="1" android:name="android.app.use_local_qt_libs"/>
<meta-data android:value="/data/local/tmp/qt/" android:name="android.app.libs_prefix"/>
<meta-data android:value="plugins/platforms/android/libqtforandroidGL.so:lib/libQt5QuickParticles.so" android:name="android.app.load_local_libs"/>
<meta-data android:value="jar/QtAndroid.jar:jar/QtAndroidAccessibility.jar:jar/QtAndroid-bundled.jar:jar/QtAndroidAccessibility-bundled.jar" android:name="android.app.load_local_jars"/>
<meta-data android:value="" android:name="android.app.static_init_classes"/>
<!-- Messages maps -->
<meta-data android:value="@string/ministro_not_found_msg" android:name="android.app.ministro_not_found_msg"/>
<meta-data android:value="@string/ministro_needed_msg" android:name="android.app.ministro_needed_msg"/>
<meta-data android:value="@string/fatal_error_msg" android:name="android.app.fatal_error_msg"/>
<!-- Messages maps -->
<!-- Splash screen -->
<meta-data android:resource="@layout/splash" android:name="android.app.splash_screen"/>
<!-- Splash screen -->
</activity>
</application>
<uses-sdk android:minSdkVersion="14" android:targetSdkVersion="19"/>
<supports-screens android:smallScreens="true" android:anyDensity="true" android:largeScreens="true" android:normalScreens="true"/>
<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
</manifest>
最佳答案
我仍然不能调用非静态函数,但是一种变通方法是使用singelton pattern,它将类的实例化限制为一个对象,并调用能够调用非静态方法的静态函数。
这是通过在构造函数中为其自身添加类/对象引用来完成的:
private static MyActivity m_instance;
public MyActivity()
{
m_instance = this;
}
现在可以在静态函数中调用非静态函数。例如,上面的非静态函数bluetoothConnect()现在可以重写为:
public static void connectBluetooth()
{
Log.d(QtApplication.QtTAG, "connectBluetooth() entered");
m_instance.bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(m_instance.bluetoothAdapter == null)
{
Log.d(QtApplication.QtTAG, "Bluetooth adapter is not found");
return;
}
if(!m_instance.bluetoothAdapter.isEnabled())
{
Log.d(QtApplication.QtTAG, "Bluetooth is off");
Intent enableBluetoothIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
m_instance.startActivityForResult(enableBluetoothIntent, ENABLE_BLUETOOTH_REQUEST);
}
else
{
Log.d(QtApplication.QtTAG, "Bluetooth is on");
m_instance.startDiscovery();
}
}
唯一的区别是将static关键字添加到方法中,并添加“m_instance”。在每个非静态方法调用之前。
现在可以从C++作为静态函数调用此函数:
QAndroidJniObject::callStaticMethod<void>("org/qtproject/qt5/android/bindings/MyActivity", "connectBluetooth");
我猜这是一个单例,它的缺点是只能制造此类的一个对象,但据我所知,它不会限制太多。
这只是一个解决方法,我对如何调用非静态函数仍然很感兴趣。该答案将不被接受为可接受的答案。