Cocos2d-x-3.6 用户交互原理---------如何通过JNI连接Java和C++

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用户交互这里指的就是用户在手机上的点击，滑动以及晃动手机等行为，从而得到相应的反馈。今天学习Cocos2dx，遇到交互问题，所以就写出来和大家分享一下。我这里是以Android连接为例的，因为目前我只会Android相关的开发。好了，不多说，看下面步骤：

第一步：在Android中，交互操作的入口在SurfaceView或是GLSurfaceView中的onTouchEvent时间中。本例代码所在位置org.cocos2dx.lib---->Cocos2dxGLSurfaceView.java

public boolean onTouchEvent(final MotionEvent pMotionEvent) {        // these data are used in ACTION_MOVE and ACTION_CANCEL        final int pointerNumber = pMotionEvent.getPointerCount();        final int[] ids = new int[pointerNumber];        final float[] xs = new float[pointerNumber];        final float[] ys = new float[pointerNumber];        for (int i = 0; i < pointerNumber; i++) {            ids[i] = pMotionEvent.getPointerId(i);            xs[i] = pMotionEvent.getX(i);            ys[i] = pMotionEvent.getY(i);        }        switch (pMotionEvent.getAction() & MotionEvent.ACTION_MASK) {            case MotionEvent.ACTION_POINTER_DOWN:                final int indexPointerDown = pMotionEvent.getAction() >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;                final int idPointerDown = pMotionEvent.getPointerId(indexPointerDown);                final float xPointerDown = pMotionEvent.getX(indexPointerDown);                final float yPointerDown = pMotionEvent.getY(indexPointerDown);                this.queueEvent(new Runnable() {                    @Override                    public void run() {                        Cocos2dxGLSurfaceView.this.mCocos2dxRenderer.handleActionDown(idPointerDown, xPointerDown, yPointerDown);                    }                });                break;            case MotionEvent.ACTION_DOWN:                // there are only one finger on the screen                final int idDown = pMotionEvent.getPointerId(0);                final float xDown = xs[0];                final float yDown = ys[0];                this.queueEvent(new Runnable() {                    @Override                    public void run() {                        Cocos2dxGLSurfaceView.this.mCocos2dxRenderer.handleActionDown(idDown, xDown, yDown);                    }                });                break;            case MotionEvent.ACTION_MOVE:                this.queueEvent(new Runnable() {                    @Override                    public void run() {                        Cocos2dxGLSurfaceView.this.mCocos2dxRenderer.handleActionMove(ids, xs, ys);                    }                });                break;            case MotionEvent.ACTION_POINTER_UP:                final int indexPointUp = pMotionEvent.getAction() >> MotionEvent.ACTION_POINTER_INDEX_SHIFT;                final int idPointerUp = pMotionEvent.getPointerId(indexPointUp);                final float xPointerUp = pMotionEvent.getX(indexPointUp);                final float yPointerUp = pMotionEvent.getY(indexPointUp);                this.queueEvent(new Runnable() {                    @Override                    public void run() {                        Cocos2dxGLSurfaceView.this.mCocos2dxRenderer.handleActionUp(idPointerUp, xPointerUp, yPointerUp);                    }                });                break;            case MotionEvent.ACTION_UP:                // there are only one finger on the screen                final int idUp = pMotionEvent.getPointerId(0);                final float xUp = xs[0];                final float yUp = ys[0];                this.queueEvent(new Runnable() {                    @Override                    public void run() {                        Cocos2dxGLSurfaceView.this.mCocos2dxRenderer.handleActionUp(idUp, xUp, yUp);                    }                });                break;            case MotionEvent.ACTION_CANCEL:                this.queueEvent(new Runnable() {                    @Override                    public void run() {                        Cocos2dxGLSurfaceView.this.mCocos2dxRenderer.handleActionCancel(ids, xs, ys);                    }                });                break;        }            return true;    }

第二步： Cocos2dxGLSurfaceView.this.mCocos2dxRenderer.handleActionDown(idDown, xDown, yDown)等相关语句的方法在org.cocos2dx.lib------>Cocos2dxRender.java，代码如下：

    private static native void nativeTouchesBegin(final int id, final float x, final float y);    private static native void nativeTouchesEnd(final int id, final float x, final float y);    private static native void nativeTouchesMove(final int[] ids, final float[] xs, final float[] ys);    private static native void nativeTouchesCancel(final int[] ids, final float[] xs, final float[] ys);       public void handleActionDown(final int id, final float x, final float y) {        Cocos2dxRenderer.nativeTouchesBegin(id, x, y);    }    public void handleActionUp(final int id, final float x, final float y) {        Cocos2dxRenderer.nativeTouchesEnd(id, x, y);    }    public void handleActionCancel(final int[] ids, final float[] xs, final float[] ys) {        Cocos2dxRenderer.nativeTouchesCancel(ids, xs, ys);    }    public void handleActionMove(final int[] ids, final float[] xs, final float[] ys) {        Cocos2dxRenderer.nativeTouchesMove(ids, xs, ys);    }

第三步： private static native void nativeTouchesBegin(final int id, final float x, final float y)这是本地方法，调用c++内容的语句。而这些内容被打包在Android工程中的libs/armeabi/cocos2dcpp.so文件中。所以我们在使用这些方法时一定要加载这个.so文件。代码位置在org.cocos2dx.lib--->Cocos2dxActivity.java，内容如下：

 protected void onLoadNativeLibraries() {        try {            ApplicationInfo ai = getPackageManager().getApplicationInfo(getPackageName(), PackageManager.GET_META_DATA);            Bundle bundle = ai.metaData;            String libName = bundle.getString("android.app.lib_name");            System.loadLibrary(libName);        } catch (Exception e) {            e.printStackTrace();        }    }

bundle.getString("android.app.lib_name")文件是找出.so文件。和它相关内容在Android工程中AndroidManifest.xml里，内容如下：

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"      package="org.cocos.CocosProject4"      android:versionCode="1"      android:versionName="1.0"      android:installLocation="auto">    <uses-sdk android:minSdkVersion="9"/>    <uses-feature android:glEsVersion="0x00020000" />    <application android:label="@string/app_name"                 android:icon="@drawable/icon">         <!-- Tell Cocos2dxActivity the name of our .so -->        <meta-data android:name="android.app.lib_name"              android:value="cocos2dcpp" />        <activity android:name="org.cocos2dx.cpp.AppActivity"                  android:label="@string/app_name"                  android:screenOrientation="landscape"                  android:theme="@android:style/Theme.NoTitleBar.Fullscreen"                  android:configChanges="orientation">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application>    <supports-screens android:anyDensity="true"                      android:smallScreens="true"                      android:normalScreens="true"                      android:largeScreens="true"                      android:xlargeScreens="true"/>    <uses-permission android:name="android.permission.INTERNET"/></manifest>

第四步：cocos2dcpp.so文件的生成，因为native 方法都在这里面。它的生成在Android工程中的jni文件里么的Android.mk文件（相关内容参考链接）。native方法所在文件路径cocos2d-x-3.6/cocos/platform/android/jni/TouchesJni.cpp,内容如下：

#include "base/CCDirector.h"#include "base/CCEventKeyboard.h"#include "base/CCEventDispatcher.h"#include "platform/android/CCGLViewImpl-android.h"#include <android/log.h>#include <jni.h>using namespace cocos2d;extern "C" {    JNIEXPORT void JNICALL Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeTouchesBegin(JNIEnv * env, jobject thiz, jint id, jfloat x, jfloat y) {        intptr_t idlong = id;        cocos2d::Director::getInstance()->getOpenGLView()->handleTouchesBegin(1, &idlong, &x, &y);    }    JNIEXPORT void JNICALL Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeTouchesEnd(JNIEnv * env, jobject thiz, jint id, jfloat x, jfloat y) {        intptr_t idlong = id;        cocos2d::Director::getInstance()->getOpenGLView()->handleTouchesEnd(1, &idlong, &x, &y);    }    JNIEXPORT void JNICALL Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeTouchesMove(JNIEnv * env, jobject thiz, jintArray ids, jfloatArray xs, jfloatArray ys) {        int size = env->GetArrayLength(ids);        jint id[size];        jfloat x[size];        jfloat y[size];        env->GetIntArrayRegion(ids, 0, size, id);        env->GetFloatArrayRegion(xs, 0, size, x);        env->GetFloatArrayRegion(ys, 0, size, y);        intptr_t idlong[size];        for(int i = 0; i < size; i++)            idlong[i] = id[i];        cocos2d::Director::getInstance()->getOpenGLView()->handleTouchesMove(size, idlong, x, y);    }    JNIEXPORT void JNICALL Java_org_cocos2dx_lib_Cocos2dxRenderer_nativeTouchesCancel(JNIEnv * env, jobject thiz, jintArray ids, jfloatArray xs, jfloatArray ys) {        int size = env->GetArrayLength(ids);        jint id[size];        jfloat x[size];        jfloat y[size];        env->GetIntArrayRegion(ids, 0, size, id);        env->GetFloatArrayRegion(xs, 0, size, x);        env->GetFloatArrayRegion(ys, 0, size, y);        intptr_t idlong[size];        for(int i = 0; i < size; i++)            idlong[i] = id[i];        cocos2d::Director::getInstance()->getOpenGLView()->handleTouchesCancel(size, idlong, x, y);    }       }

第五步：cocos2d::Director::getInstance()->getOpenGLView()->handleTouchesBegin(1, &idlong, &x, &y)这个方法是如何起作用的呢，文件位置在cocos2d-x-3.6/cocos/platform/CCGLView.cpp，内如如下：

void GLView::handleTouchesBegin(int num, intptr_t ids[], float xs[], float ys[]){    intptr_t id = 0;    float x = 0.0f;    float y = 0.0f;    int unusedIndex = 0;    EventTouch touchEvent;        for (int i = 0; i < num; ++i)    {        id = ids[i];        x = xs[i];        y = ys[i];        auto iter = g_touchIdReorderMap.find(id);        // it is a new touch        if (iter == g_touchIdReorderMap.end())        {            unusedIndex = getUnUsedIndex();            // The touches is more than MAX_TOUCHES ?            if (unusedIndex == -1) {                CCLOG("The touches is more than MAX_TOUCHES, unusedIndex = %d", unusedIndex);                continue;            }            Touch* touch = g_touches[unusedIndex] = new (std::nothrow) Touch();touch->setTouchInfo(unusedIndex, (x - _viewPortRect.origin.x) / _scaleX,                                     (y - _viewPortRect.origin.y) / _scaleY);                        CCLOGINFO("x = %f y = %f", touch->getLocationInView().x, touch->getLocationInView().y);                        g_touchIdReorderMap.insert(std::make_pair(id, unusedIndex));            touchEvent._touches.push_back(touch);        }    }    if (touchEvent._touches.size() == 0)    {        CCLOG("touchesBegan: size = 0");        return;    }        touchEvent._eventCode = EventTouch::EventCode::BEGAN;    auto dispatcher = Director::getInstance()->getEventDispatcher();    dispatcher->dispatchEvent(&touchEvent);}

第六步：使用。首先要给_eventDispathcer(在CCNote.cpp文件中)添加listener,示例如下：

 auto listener = EventListenerTouchAllAtOnce::create();    listener->onTouchesBegan = CC_CALLBACK_2(ParticleDemo::onTouchesBegan, this);    listener->onTouchesMoved = CC_CALLBACK_2(ParticleDemo::onTouchesMoved, this);    listener->onTouchesEnded = CC_CALLBACK_2(ParticleDemo::onTouchesEnded, this);    _eventDispatcher->addEventListenerWithSceneGraphPriority(listener, this);

其次就是我们实际操作，使交互产生什么样的变化，代码如下：

void ParticleDemo::onTouchesBegan(const std::vector<Touch*>& touches, Event  *event){    onTouchesEnded(touches, event);}void ParticleDemo::onTouchesMoved(const std::vector<Touch*>& touches, Event  *event){    return onTouchesEnded(touches, event);}void ParticleDemo::onTouchesEnded(const std::vector<Touch*>& touches, Event  *event){    auto touch = touches[0];    auto location = touch->getLocation();    auto pos = Vec2::ZERO;    if (_background)    {        pos = _background->convertToWorldSpace(Vec2::ZERO);    }    if (_emitter != nullptr)    {        _emitter->setPosition(location -pos);    }}

上面代码是ParticleTest中的内容，通过dispathcer将参数最终传递给要变化的_mitter，就是粒子发射器的移动。

好了，以上就是这个过程，当然，要想完全理解，那就要修炼内功了，怎么做，你懂的~

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