我正在编写一个OpenGL C/C++应用程序,通过Android NDK,JNI支持将其移植到Android。从本机发出的JAVA回调中执行代码时遇到困难。从本地C/C++代码调用JAVA类成员
下面是代码:
class OpenGLSurfaceView extends GLSurfaceView
{
…
public OpenGLSurfaceView(Context context, int deviceWidth, int deviceHeight)
{
super(context);
nativeObj = new NativeLib();
mRenderer = new OpenGLRenderer(context, nativeObj, deviceWidth, deviceHeight);
setRenderer(mRenderer);
setRenderMode(RENDERMODE_WHEN_DIRTY);
}
…
private void CallBack()
{
// force redraw
requestRender();
}
}
class OpenGLRenderer implements GLSurfaceView.Renderer
{
…
public void onSurfaceCreated(GL10 gl, EGLConfig config)
{
nativeObj.init(…);
nativeObj.cachejavaobject(JNIEnv *env, jobject obj); // for caching obj on native side
}
public void onSurfaceChanged(GL10 gl, int w, int h)
{
}
public void onDrawFrame(GL10 gl)
{
nativeObj.draw(…);
}
}
而且在本机代码我有一个功能texturesLoaded()时,一些纹理在另一个线程完全加载信号通知,我需要强制从nativeLib.draw刷新(......)在JAVA端。这是我如何做到这一点:
我缓存在JavaVM,JCLASS,jMethodID上JNI_OnLoad和gJObjectCached
JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved)
{
gJVM = jvm; // cache the JavaVM pointer
LogNativeToAndroidExt("JNILOAD!!!!!!!!!!");
JNIEnv *env;
int status = gJVM->GetEnv((void **)&env, JNI_VERSION_1_6);
if(status < 0)
{
LogNativeToAndroidExt("Failed to get JNI environment, assuming native thread");
status = gJVM->AttachCurrentThread(&env, NULL);
if(status < 0)
{
LogNativeToAndroidExt("callback_handler: failed to attach current thread");
return JNI_ERR;
}
}
gJClass = env->FindClass("com/android/newlineactivity/NewLineGLSurfaceView");
if(gJClass == NULL)
{
LogNativeToAndroidExt("Can't find Java class.");
return JNI_ERR;
}
gJMethodID = env->GetMethodID(gJClass, "callback", "()V");
if(gJMethodID == NULL)
{
LogNativeToAndroidExt("Can't find Java method void callback()");
return JNI_ERR;
}
return JNI_VERSION_1_6;
}
JNIEXPORT void Java_com_android_OpenGL_NativeLib_cachejavaobject(JNIEnv* env, jobject obj)
{
// cache the java object
gJObjectCached = obj;
...
}
,然后texturesLoaded()我做的:
void texturesLoaded()
{
// Cannot share a JNIEnv between threads. You should share the JavaVM, and use JavaVM->GetEnv to discover the thread's JNIEnv
JNIEnv *env = NULL;
int status = gJVM->GetEnv((void **)&env, JNI_VERSION_1_6);
if(status < 0)
{
LogNativeToAndroidExt("callback_handler: failed to get JNI environment, assuming native thread");
status = gJVM->AttachCurrentThread(&env, NULL);
if(status < 0)
{
LogNativeToAndroidExt("callback_handler: failed to attach current thread");
return;
}
}
LogNativeToAndroidExt("Calling JAVA method from NATIVE C/C++");
env->CallVoidMethod(gJObjectCached, gJMethodID);
LogNativeToAndroidExt("DONE!!!");
}
结果...从本机端我得到类,我得到的方法,方法被调用,但是当它达到/ cal ls requestRender()里面(或试图访问任何其他成员方法的GLSurfaceView它崩溃!)
我不能尝试使用CallStaticVoidMethod(gJClass,gjMethodID);因为那样我就无法访问requestRender();
任何想法或意见,也许我在这里做错了什么。
感谢
'requestRender()'是Java,所以崩溃通常都伴随着一个例外。你能提一下那个例外吗? Android ADB日志应该显示这些信息。去[这里](http://developer.android.com/guide/developing/debugging/debugging-log.html)找出关于日志 – Warpspace