基于Android framework，帮我写一个native层获取GPS信息的功能

好的，以下是基于Android framework的native层获取GPS信息的功能实现：

1. 首先，需要在Android.mk文件中添加如下代码：

LOCAL_LDLIBS += -llog -lm -lhardware
LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
LOCAL_SRC_FILES := gps.c

2. 在include文件夹下创建gps.h头文件，并添加如下代码：

#ifndef GPS_H
#define GPS_H

#include <jni.h>

#ifdef __cplusplus
extern "C" {
#endif

JNIEXPORT void JNICALL Java_com_example_gps_GPSManager_start(JNIEnv *env, jobject instance);
JNIEXPORT void JNICALL Java_com_example_gps_GPSManager_stop(JNIEnv *env, jobject instance);
JNIEXPORT jdouble JNICALL Java_com_example_gps_GPSManager_getLatitude(JNIEnv *env, jobject instance);
JNIEXPORT jdouble JNICALL Java_com_example_gps_GPSManager_getLongitude(JNIEnv *env, jobject instance);

#ifdef __cplusplus
}
#endif

#endif //GPS_H

3. 在native层的gps.c文件中实现相关的函数，并添加如下代码：

#include <jni.h>
#include <android/log.h>
#include <hardware/gps.h>

#define TAG "GPS"
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, TAG, __VA_ARGS__)

static struct gps_device_t *s_gps_device = NULL;
static GpsCallbacks s_gps_callbacks;

static void location_callback(GpsLocation *location) {
    LOGD("latitude = %f, longitude = %f", location->latitude, location->longitude);
}

JNIEXPORT void JNICALL Java_com_example_gps_GPSManager_start(JNIEnv *env, jobject instance) {
    if (s_gps_device == NULL) {
        hw_module_t *module;
        if (hw_get_module(GPS_HARDWARE_MODULE_ID, (const hw_module_t **)&module) == 0) {
            if (module->methods->open(module, GPS_HARDWARE_MODULE_ID, (hw_device_t **)&s_gps_device) == 0) {
                s_gps_callbacks.location_cb = location_callback;
                s_gps_device->set_position_mode(&s_gps_callbacks, GPS_POSITION_MODE_MS_BASED, 0, 0, 0);
                s_gps_device->start();
            }
        }
    }
}

JNIEXPORT void JNICALL Java_com_example_gps_GPSManager_stop(JNIEnv *env, jobject instance) {
    if (s_gps_device != NULL) {
        s_gps_device->stop();
        s_gps_device->close();
        s_gps_device = NULL;
    }
}

JNIEXPORT jdouble JNICALL Java_com_example_gps_GPSManager_getLatitude(JNIEnv *env, jobject instance) {
    if (s_gps_device != NULL) {
        GpsLocation location;
        s_gps_device->get_location(&location);
        return location.latitude;
    }
    return 0;
}

JNIEXPORT jdouble JNICALL Java_com_example_gps_GPSManager_getLongitude(JNIEnv *env, jobject instance) {
    if (s_gps_device != NULL) {
        GpsLocation location;
        s_gps_device->get_location(&location);
        return location.longitude;
    }
    return 0;
}

4. 在Java层创建一个GPSManager类，并添加如下代码：

package com.example.gps;

public class GPSManager {
    static {
        System.loadLibrary("gps");
    }

    public static native void start();
    public static native void stop();
    public static native double getLatitude();
    public static native double getLongitude();
}

5. 最后，在需要获取GPS信息的地方调用相关函数即可，如下：

GPSManager.start();
double latitude = GPSManager.getLatitude();
double longitude = GPSManager.getLongitude();
GPSManager.stop();

以上就是基于Android framework的native层获取GPS信息的功能实现方法。