getClass

GetClassDemo demo = new GetClassDemo();
Class clazz = demo.getClass(); // 初始化的class
System.out.println("clazz="+clazz);

native方法

public final native Class getClass();

openjdk8jdksrcsharenativejavalangObject.c

JNIEXPORT jclass JNICALL
Java_java_lang_Object_getClass(JNIEnv *env, jobject this)
{
    if (this == NULL) {
        JNU_ThrowNullPointerException(env, NULL);
        return 0;
    } else {
        return (*env)->GetObjectClass(env, this);  //todo getClass()
    }
}

openjdk8hotspotsrcsharevmprimsjni.cpp

JNIWrapper("GetObjectClass");
JNI_ENTRY(jclass, jni_GetObjectClass(JNIEnv *env, jobject obj))
#ifndef USDT2
  DTRACE_PROBE2(hotspot_jni, GetObjectClass__entry, env, obj);
#else 
  HOTSPOT_JNI_GETOBJECTCLASS_ENTRY(
                                   env, obj);
#endif 
  Klass* k = JNIHandles::resolve_non_null(obj)->klass(); 
  jclass ret =
    (jclass) JNIHandles::make_local(env, k->java_mirror());   //jniHandles.cpp:63
#ifndef USDT2
  DTRACE_PROBE1(hotspot_jni, GetObjectClass__return, ret);
#else 
  HOTSPOT_JNI_GETOBJECTCLASS_RETURN(
                                    ret);
#endif 
  return ret;
JNI_END

openjdk8hotspotsrcsharevmruntimejniHandles.hpp

inline oop JNIHandles::resolve_non_null(jobject handle) {
  oop result = *(oop*)handle;
  return result;
};