Android: 用jni 获取MAC地址_综合

首先来看看mac地址获取的java实现代码：

public String getLocalMacAddress(Context context) {WifiManager wifi = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);WifiInfo info = wifi.getConnectionInfo();return info.getMacAddress();
}

代码相当简单。就两个对象：WifiManager 和 WifiInfo对象，所以这个翻译成jni代码也不会有多复杂。

先在jni获取WifiManager 对象：

/*
 * 获取WifiManager 对象
 * 参数： jCtxObj 为Context对象
 */
jobject getWifiManagerObj(JNIEnv *env, jclass clz, jobject jCtxObj)
{LOGI("gotWifiMangerObj ");//获取 Context.WIFI_SERVICE 的值//jstring  jstr_wifi_serveice = env->NewStringUTF("wifi");jclass jCtxClz= env->FindClass("android/content/Context");jfieldID fid_wifi_service = env->GetStaticFieldID(jCtxClz,"WIFI_SERVICE","Ljava/lang/String;");jstring  jstr_wifi_serveice = (jstring)env->GetStaticObjectField(jCtxClz,fid_wifi_service);jclass jclz = env->GetObjectClass(jCtxObj);jmethodID  mid_getSystemService = env->GetMethodID(jclz,"getSystemService","(Ljava/lang/String;)Ljava/lang/Object;");jobject wifiManager = env->CallObjectMethod(jCtxObj,mid_getSystemService,jstr_wifi_serveice);//因为jclass 继承自 jobject，所以需要释放；//jfieldID、jmethodID是内存地址，这段内存也不是在我们代码中分配的，不需要我们来释放。env->DeleteLocalRef(jCtxClz);env->DeleteLocalRef(jclz);env->DeleteLocalRef(jstr_wifi_serveice);return wifiManager;
}

然后，再获取WifiInfo对象：

/*
 * 获取WifiInfo 对象
 * 参数： wifiMgrObj 为WifiManager对象
 */
jobject getWifiInfoObj(JNIEnv *env, jobject wifiMgrObj)
{LOGI("getWifiInfoObj ");if(wifiMgrObj == NULL){return NULL;    }jclass jclz = env->GetObjectClass(wifiMgrObj);jmethodID mid = env->GetMethodID(jclz,"getConnectionInfo","()Landroid/net/wifi/WifiInfo;");jobject wifiInfo = env->CallObjectMethod(wifiMgrObj,mid);env->DeleteLocalRef(jclz);return wifiInfo;
}

现在只差最后一步了，调用WifiInfo的getMacAddress()方法：

/*
 * 获取MAC地址
 * 参数：wifiInfoObj， WifiInfo的对象
 */
char* getMacAddress(JNIEnv *env, jobject wifiInfoObj)
{LOGI("getMacAddress.... ");if(wifiInfoObj == NULL){return NULL;}jclass jclz = env->GetObjectClass(wifiInfoObj);jmethodID mid = env->GetMethodID(jclz,"getMacAddress","()Ljava/lang/String;");jstring jstr_mac = (jstring)env->CallObjectMethod(wifiInfoObj,mid);if(jstr_mac == NULL){env->DeleteLocalRef(jclz);return NULL;}const char* tmp = env->GetStringUTFChars(jstr_mac, NULL);char* mac = (char*) malloc(strlen(tmp)+1);memcpy(mac,tmp,strlen(tmp)+1);env->ReleaseStringUTFChars(jstr_mac, tmp);env->DeleteLocalRef(jclz);return mac;
}

只需要把这三个过程串起来就ok了

jobject wifiManagerObj = getWifiManagerObj(env, clz, jCtxObj);
jobject wifiInfoObj = getWifiInfoObj(env,wifiManagerObj);
char * mac = getMacAddress(env,wifiInfoObj);