首先在java层定义一个buffer,并且开辟相应的内存空间

private ByteBuffer byteBuffer;
byteBuffer = ByteBuffer.allocateDirect(bytesPerFrame * framesPerBuffer );

然后调用本地的方法来设置内存地址到native层，该方法在jni初始化时就已经被动态的注册了方法,注册的时候直接调用了底层的c++代码并且，通过java底层操作获取了buffer的内存地址，保存到了native c++中

nativeCacheDirectBufferAddress(byteBuffer, nativeAudioRecord);

{ALOGD("ctor%s", GetThreadInfo().c_str());// RTC_DCHECK(audio_parameters_.is_valid());// RTC_CHECK(j_environment_);JNINativeMethod native_methods[] = {{"nativeCacheDirectBufferAddress", "(Ljava/nio/ByteBuffer;J)V",reinterpret_cast<void*>(&webrtc::AudioRecordJni::CacheDirectBufferAddress)},{"nativeDataIsRecorded", "(IJ)V",reinterpret_cast<void*>(&webrtc::AudioRecordJni::DataIsRecorded)}};j_native_registration_ = j_environment_->RegisterNatives("com/ifreetalk/ftalk/module/audio/engine/AudioRecord",native_methods, arraysize(native_methods));j_audio_record_.reset(new JavaAudioRecord(j_native_registration_.get(),j_native_registration_->NewObject("<init>", "(Landroid/content/Context;J)V",JVM::GetInstance()->context(), PointerTojlong(this))));// Detach from this thread since we want to use the checker to verify calls// from the Java based audio thread.thread_checker_java_.DetachFromThread();
}
void JNICALL AudioRecordJni::CacheDirectBufferAddress(JNIEnv* env, jobject obj, jobject byte_buffer, jlong nativeAudioRecord) {webrtc::AudioRecordJni* this_object =reinterpret_cast<webrtc::AudioRecordJni*> (nativeAudioRecord);this_object->OnCacheDirectBufferAddress(env, byte_buffer);
}void AudioRecordJni::OnCacheDirectBufferAddress(JNIEnv* env, jobject byte_buffer) {//ALOGD("OnCacheDirectBufferAddress");//RTC_DCHECK(thread_checker_.CalledOnValidThread());//RTC_DCHECK(!direct_buffer_address_);direct_buffer_address_ =//内存地址映射env->GetDirectBufferAddress(byte_buffer);jlong capacity = env->GetDirectBufferCapacity(byte_buffer);//计算内存大小
//  ALOGD("direct buffer capacity: %lld", capacity);direct_buffer_capacity_in_bytes_ = static_cast<size_t>(capacity);//960
}void JNICALL AudioRecordJni::DataIsRecorded(JNIEnv* env, jobject obj, jint length, jlong nativeAudioRecord) {webrtc::AudioRecordJni* this_object =reinterpret_cast<webrtc::AudioRecordJni*> (nativeAudioRecord);this_object->OnDataIsRecorded(length);
}