Get the pointer of a Java ByteBuffer though JNI

问题

How can I get a pointer to the inner array of a Java ByteBuffer?

JNIEXPORT void JNICALL test(JNIEnv *env, jobject thiso) {
    jclass cls = env->FindClass("java/nio/ByteBuffer");
    jmethodID aloc = env->GetStaticMethodID(cls, "allocateDirect", "(I)Ljava/nio/ByteBuffer;");
    jobject obj = env->CallStaticObjectMethod(cls, aloc, 1000);
}

PS: I'm doing that to share the memory used by Java and C++.

回答1:

void * data = env->GetDirectBufferAddress(obj);

The ByteBuffer must be a direct one for this to work.

回答2:

If you're trying to return the address of the first element within m_buffer, then you can just do:

return m_buffer;

..or:

return &m_buffer[0]

来源：https://stackoverflow.com/questions/8000548/get-the-pointer-of-a-java-bytebuffer-though-jni