自学教程：C++ GetMethodID函数代码示例

        //---------------------------------------------------------------        //---------------------------------------------------------------        void GooglePlayIAPJavaInterface::StartListeningForTransactionUpdates(const CSNetworking::IAPSystem::TransactionStatusDelegate& in_delegate)        {        	CS_ASSERT(in_delegate != nullptr, "Cannot have null transaction delegate");        	m_transactionStatusDelegate = in_delegate;        	JNIEnv* env = JavaInterfaceManager::GetSingletonPtr()->GetJNIEnvironmentPtr();        	env->CallVoidMethod(GetJavaObject(), GetMethodID("RestorePendingUnmanagedTransactions"));        	Json::Value jData;        	if(CSCore::JsonUtils::ReadJson(CSCore::StorageLocation::k_cache, k_pendingCacheFile, jData))        	{        		const Json::Value::Members& members = jData.getMemberNames();        		jobjectArray transactionIDs = env->NewObjectArray(members.size(), env->FindClass("java/lang/String"), env->NewStringUTF(""));        		u32 index = 0;        		for(Json::Value::Members::const_iterator it = members.begin(); it != members.end(); ++it, ++index)        		{    				jstring jtransactionId = JavaInterfaceUtils::CreateJStringFromSTDString(*it);    				env->SetObjectArrayElement(transactionIDs, index, jtransactionId);    				env->DeleteLocalRef(jtransactionId);        		}            	env->CallVoidMethod(GetJavaObject(), GetMethodID("RestorePendingManagedTransactions"), transactionIDs);            	env->DeleteLocalRef(transactionIDs);        	}        }

    ActivityState* ActivityState::create(ANativeActivity* activity)    {        JOP_ASSERT(ns_instance == nullptr, "There must only be one ActivityState!");        ns_instance.reset(new ActivityState);        ns_instance->nativeActivity = activity;        ANativeActivity_setWindowFlags(activity, AWINDOW_FLAG_KEEP_SCREEN_ON, AWINDOW_FLAG_KEEP_SCREEN_ON);        Thread::attachJavaThread(activity->vm, activity->env);        // Get the screen size        {            auto env = Thread::getCurrentJavaEnv();            if (!env)            {                JOP_DEBUG_ERROR("No current java environment, function /"" << __func__ << "/"");                return get();            }            jclass activityClass = env->GetObjectClass(activity->clazz);            jclass displayMetricsClass = env->FindClass("android/util/DisplayMetrics");            jmethodID displayMetricsInit = env->GetMethodID(displayMetricsClass, "<init>", "()V");            jobject displayMetricsObject = env->NewObject(displayMetricsClass, displayMetricsInit);            jmethodID getWindowManagerMethod = env->GetMethodID(activityClass, "getWindowManager", "()Landroid/view/WindowManager;");            jobject windowManagerObject = env->CallObjectMethod(activity->clazz, getWindowManagerMethod);            jclass windowManagerClass = env->FindClass("android/view/WindowManager");            jmethodID getDefaultDisplayMethod = env->GetMethodID(windowManagerClass, "getDefaultDisplay", "()Landroid/view/Display;");            jobject displayObject = env->CallObjectMethod(windowManagerObject, getDefaultDisplayMethod);            jclass displayClass = env->FindClass("android/view/Display");            jmethodID getMetricsMethod = env->GetMethodID(displayClass, "getMetrics", "(Landroid/util/DisplayMetrics;)V");            env->CallVoidMethod(displayObject, getMetricsMethod, displayMetricsObject);            jfieldID pixelsWidth = env->GetFieldID(displayMetricsClass, "widthPixels", "I");            jfieldID pixelsHeight = env->GetFieldID(displayMetricsClass, "heightPixels", "I");            ns_instance->screenSize.x = env->GetIntField(displayMetricsObject, pixelsWidth);            ns_instance->screenSize.y = env->GetIntField(displayMetricsObject, pixelsHeight);            //jmethodID getRefreshRateMethod = env->GetMethodID(displayClass, "getRefreshRate", "(Landroid/view/Display;)F");            ns_instance->screenRefreshRate = 60;//env->CallFloatMethod(displayObject, getRefreshRateMethod);            env->DeleteLocalRef(activityClass);            env->DeleteLocalRef(displayMetricsObject);            env->DeleteLocalRef(windowManagerObject);            env->DeleteLocalRef(windowManagerClass);            env->DeleteLocalRef(displayObject);            env->DeleteLocalRef(displayClass);        }        return get();    }

template <class R> GVRActivityT<R>::GVRActivityT(JNIEnv & jni_, jobject activityObject_)    : forceScreenClear( false )    , ModelLoaded( false )    , UiJni(&jni_)    , viewManager(NULL){    viewManager = new GVRViewManager(jni_,activityObject_);    javaObject = UiJni->NewGlobalRef( activityObject_ );    activityClass = GetGlobalClassReference( activityClassName );    vrAppSettingsClass = GetGlobalClassReference(app_settings_name);    oneTimeInitMethodId = GetMethodID("oneTimeInit", "()V");    oneTimeShutdownMethodId = GetMethodID("oneTimeShutDown", "()V");    drawFrameMethodId = GetMethodID("drawFrame", "()V");    beforeDrawEyesMethodId = GetMethodID("beforeDrawEyes", "()V");    drawEyeViewMethodId = GetMethodID("onDrawEyeView", "(IF)V");    afterDrawEyesMethodId = GetMethodID("afterDrawEyes", "()V");    onKeyEventNativeMethodId = GetMethodID("onKeyEventNative", "(II)Z");    updateSensoredSceneMethodId = GetMethodID("updateSensoredScene", "()Z");    getAppSettingsMethodId = GetMethodID("getAppSettings",            "()Lorg/gearvrf/utility/VrAppSettings;");}

JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *pjvm, void *reserved) {	ILOG("JNI_OnLoad");	gJvm = pjvm;  // cache the JavaVM pointer	auto env = getEnv();	//replace with one of your classes in the line below	auto randomClass = env->FindClass("org/ppsspp/ppsspp/NativeActivity");	jclass classClass = env->GetObjectClass(randomClass);	auto classLoaderClass = env->FindClass("java/lang/ClassLoader");	auto getClassLoaderMethod = env->GetMethodID(classClass, "getClassLoader",												 "()Ljava/lang/ClassLoader;");	gClassLoader = env->NewGlobalRef(env->CallObjectMethod(randomClass, getClassLoaderMethod));	gFindClassMethod = env->GetMethodID(classLoaderClass, "findClass",										"(Ljava/lang/String;)Ljava/lang/Class;");	return JNI_VERSION_1_6;}

static void bitmap_dispose(Class *cl, Object *obj, Msg *msg){    struct HIDDBitMapAmigaIntuiData *data = INST_DATA(cl, obj);    struct pHidd_BitMap_PrivateSet private_set_msg;    EnterFunc(bug("BitMapAmigaIntui::Dispose()/n"));    if(data->screen)    {        /*           We use an own buffer so set the BaseAddress to NULL to prevent           the superclass to free our own buffer.        */        struct TagItem set[] =        {            {aHidd_BitMap_BaseAddress, NULL},            {TAG_END                 , 0   }        };        CloseScreen(data->screen);        private_set_msg.mID      = GetMethodID(IID_Hidd_BitMap, moHidd_BitMap_PrivateSet);        private_set_msg.attrList = set;        DoSuperMethod(cl, obj, (Msg) &private_set_msg);    }    DoSuperMethod(cl, obj, (Msg) msg);    ReturnVoid("BitMapAmigaIntui::Dispose");}

bool NetCenter::ConnectServiceWhitFD(int fd , const char* host_name, int port){    if (!_run_flg)    {        return false;    }    SocketAddress addr(host_name, port);    CriticalSectionScoped css(&cs_);    std::map<SOCKET, struct stSocketObj*>::iterator it = socket_objs.find(fd);    if (socket_objs.end() == it)    {        return false;    }    if (it->second->dispatch->Connect(addr) != 0)    {        return false;    }    if (it->second->dispatch->GetState() == jsbn::AsyncSocket::CS_CONNECTED)    {        jmethodID m = GetMethodID(jni(), *j_observer_class_, "StatusReportWithFD", "(II)V");        jni()->CallVoidMethod(*j_observer_global_, m, it->second->dispatch->GetDescriptor(), (int)ENE_CONNECTED);    }    return true;}

		//-------------------------------------------------------		//-------------------------------------------------------		void TextEntryJavaInterface::SetTextBuffer(const std::string& in_text)		{        	JNIEnv* env = JavaInterfaceManager::GetSingletonPtr()->GetJNIEnvironmentPtr();        	jstring text = JavaInterfaceUtils::CreateJStringFromSTDString(in_text);        	env->CallVoidMethod(GetJavaObject(), GetMethodID("setTextBuffer"), text);        	env->DeleteLocalRef(text);		}

		//--------------------------------------------------------------		/// Present		//--------------------------------------------------------------		void EmailComposerJavaInterface::Present(const std::vector<std::string>& inastrRecipientAddresses, const std::string& instrSubject, const std::string& instrContents,				bool inbFormatAsHtml, const std::string& instrAttachmentFilename, const ResultDelegate& inDelegate)		{			mDelegate = inDelegate;			JNIEnv* pEnv = JavaInterfaceManager::GetSingletonPtr()->GetJNIEnvironmentPtr();			//build the recipient list			u32 udwCount = 0;			jobjectArray ajstrRecipients = pEnv->NewObjectArray(inastrRecipientAddresses.size(), pEnv->FindClass("java/lang/String"), pEnv->NewStringUTF(""));			for(auto it = inastrRecipientAddresses.begin(); it != inastrRecipientAddresses.end(); ++it)			{				jstring jstrRecipient = JavaUtils::CreateJStringFromSTDString(*it);				pEnv->SetObjectArrayElement(ajstrRecipients,udwCount++, jstrRecipient);				pEnv->DeleteLocalRef(jstrRecipient);			}			jstring jstrSubject = JavaUtils::CreateJStringFromSTDString(instrSubject);			jstring jstrContents = JavaUtils::CreateJStringFromSTDString(instrContents);			jstring jstrAttachmentFilename = JavaUtils::CreateJStringFromSTDString(instrAttachmentFilename);			//call method			pEnv->CallVoidMethod(GetJavaObject(), GetMethodID("Present"), ajstrRecipients, jstrSubject, jstrContents, inbFormatAsHtml, jstrAttachmentFilename);			//clean up			pEnv->DeleteLocalRef(ajstrRecipients);			pEnv->DeleteLocalRef(jstrSubject);			pEnv->DeleteLocalRef(jstrContents);			pEnv->DeleteLocalRef(jstrAttachmentFilename);		}

        //---------------------------------------------------------------        //---------------------------------------------------------------        void AmazonIAPJavaInterface::StopListeningForTransactionUpdates()        {        	m_transactionStatusDelegate = nullptr;        	JNIEnv* env = JavaInterfaceManager::GetSingletonPtr()->GetJNIEnvironmentPtr();        	env->CallVoidMethod(GetJavaObject(), GetMethodID("StopListeningForTransactionUpdates"));        }

        //---------------------------------------------------------------        //---------------------------------------------------------------        void AmazonIAPJavaInterface::RequestProductDescriptions(const std::vector<std::string>& in_productIds, const CSNetworking::IAPSystem::ProductDescDelegate& in_delegate)        {            CS_ASSERT(in_productIds.empty() == false, "Cannot request no product descriptions");            CS_ASSERT(in_delegate != nullptr, "Cannot have null product description delegate");            CS_ASSERT(m_productsRequestDelegate == nullptr, "Only 1 product description request can be active at a time");        	m_productsRequestDelegate = in_delegate;        	JNIEnv* env = JavaInterfaceManager::GetSingletonPtr()->GetJNIEnvironmentPtr();			jstring jstrEmptyString = env->NewStringUTF("");			jclass jStringClass = env->FindClass("java/lang/String");        	jobjectArray productIDs = env->NewObjectArray(in_productIds.size(), jStringClass, jstrEmptyString);        	u32 productIDIndex = 0;        	for(std::vector<std::string>::const_iterator it = in_productIds.begin(); it != in_productIds.end(); ++it)        	{        		jstring productID = JavaUtils::CreateJStringFromSTDString(*it);        		env->SetObjectArrayElement(productIDs, productIDIndex, productID);        		env->DeleteLocalRef(productID);        		productIDIndex++;        	}        	env->CallVoidMethod(GetJavaObject(), GetMethodID("RequestProductDescriptions"), productIDs);        	env->DeleteLocalRef(productIDs);			env->DeleteLocalRef(jstrEmptyString);			env->DeleteLocalRef(jStringClass);        }

        //-----------------------------------------------------------------------------------------------------        //-----------------------------------------------------------------------------------------------------        TimeIntervalMs CoreJavaInterface::GetSystemTimeInMilliseconds()        {        	TimeIntervalMs output = 0;			JNIEnv* env = JavaInterfaceManager::GetSingletonPtr()->GetJNIEnvironmentPtr();			output = (TimeIntervalMs)env->CallLongMethod(GetJavaObject(), GetMethodID("getSystemTimeInMilliseconds"));			return output;        }

        //------------------------------------------------------        //------------------------------------------------------        void DialogueBoxJavaInterface::MakeToast(const std::string& in_text)        {			JNIEnv* env = JavaInterfaceManager::GetSingletonPtr()->GetJNIEnvironmentPtr();			jstring message = JavaInterfaceUtils::CreateJStringFromSTDString(in_text);			env->CallVoidMethod(GetJavaObject(), GetMethodID("makeToast"), message);			env->DeleteLocalRef(message);        }

jobject invokeStaticMethod(JNIEnv* env, const char* class_name,		const char* method_name, const char* sig, jclass pareValues[]){	jclass obj_class = FindClass(env, class_name);	jmethodID methodId = GetMethodID(obj_class, method_name, sig);}

		//------------------------------------------------		/// Stop Listening		//------------------------------------------------		void AccelerometerJavaInterface::StopListening()		{			if (true == mbListening)			{				mAccelerationChangedDelegate = nullptr;				JNIEnv* pEnv = JavaInterfaceManager::GetSingletonPtr()->GetJNIEnvironmentPtr();				pEnv->CallVoidMethod(GetJavaObject(), GetMethodID("StopListening"));				mbListening = false;			}		}

void MeganekkoActivity::OneTimeShutdown(){    delete SoundEffectPlayer;    SoundEffectPlayer = NULL;    delete SoundEffectContext;    SoundEffectContext = NULL;    jmethodID oneTimeShutdownMethodId = GetMethodID("oneTimeShutDown", "()V");    app->GetJava()->Env->CallVoidMethod(app->GetJava()->ActivityObject, oneTimeShutdownMethodId);}