JNI C++ 사용예

JNI C++ 사용 예제

Android.mk
LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_LDLIBS := -lm -llog
LOCAL_SHARED_LIBRARIES := liblog libcutils

LOCAL_DEFAULT_CPP_EXTENSION := cpp
LOCAL_MODULE := mylib
LOCAL_SRC_FILES := \
    main.cpp \
    http_get.cpp \

include $(BUILD_SHARED_LIBRARY)

Main.cpp
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <jni.h>
#include <assert.h>

#include "http_get.h"

#include <android/log.h>
#define LOG_TAG "MY"
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
#define LOGW(...) __android_log_print(ANDROID_LOG_WARN,LOG_TAG,__VA_ARGS__)
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG,LOG_TAG,__VA_ARGS__)
#define LOGV(...) __android_log_print(ANDROID_LOG_VERBOSE,LOG_TAG,__VA_ARGS__)


extern "C" {

JNIEXPORT jstring JNICALL native_hello(JNIEnv *env, jclass clazz)
{
    printf("hello in native code.");

    mmain();
    return env->NewStringUTF("-------------hello world mmain().-------------");
}

#define JNIREG_CLASS "ub/test/hellojni/HelloJniActivity"

static JNINativeMethod gMethods[] = {
        { "native_hello", "()Ljava/lang/String;", (void*)native_hello },
        }; /* * Register several native methods for one class. */

static int registerNativeMethods(JNIEnv* env, const char* className, JNINativeMethod* gMethods, int numMethods)
{
    jclass clazz;
    clazz = env->FindClass(className);
    if (clazz == NULL)
    {
        return JNI_FALSE;
    }
    if (env->RegisterNatives(clazz, gMethods, numMethods) < 0)
    {
        return JNI_FALSE;
    }

    return JNI_TRUE; }

/* * Register native methods for all classes we know about. */
static int registerNatives(JNIEnv* env)
{
    if (!registerNativeMethods(env, JNIREG_CLASS, gMethods, sizeof(gMethods) / sizeof(gMethods[0])))
    {
        return JNI_FALSE;
    }
    return JNI_TRUE;
}

JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved)
{
    JNIEnv* env = NULL;
    jint result = -1;
    if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK)
    {
        return -1;
    }
    assert(env != NULL);
    if (!registerNatives(env))
    {
        return -1;
    }
    /* success -- return valid version number */
    result = JNI_VERSION_1_4;
    return result;
}

}

HelloJniActivity.java
package ub.test.hellojni;


public class HelloJniActivity extends Activity {
    /** Called when the activity is first created. */

public native String  native_hello();


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Log.v("MY", "onCreate! " + native_hello());
    }

    static {
        System.loadLibrary("mylib");
      }
}