qt on android之GPS信号的获取

0.      写在最前面

本人參考安晓辉大侠的一篇博文后。做了Qt on android的GSP相关的实验。为了后面不时之需。故而记录下来。

1.      Qt on Android GPS系统流程

图1. 系统流程图

如图1所看到的，系统含两个层面：其一为基于QT的UI。提供启动GPS的button(QPushButton)。以及显示GPS信号的文本域(QTextBrowser)。其二为基于Activity的GPS服务，提供GPS的启动，GPS信号上报等服务。两个层面的交互及C++与Java的交互通过JNI来实现。

系统的总体线索如箭头方式所看到的：在QT层，button被点击后。槽函数startGps被触发。该函数调用Activity层的方法calledByCpp，而calledByCpp方法发送消息到mes handle，消息类型为MSG_STR_GPS_LOC。handle收到消息后。调用函数startAmap启动GPS的定位。GPS启动后，位置的实时信息在函数onLocationChanged()函数中公布，该函数把位置信息通过消息发送给msg
handle，当中消息类型为MSG_RPT_GSP_INF。handle再调用native方法reportGpsInfo，就能够把消息发送给QT层。

2.      创建Androidproject

图2 创建project

project命名为QtAndroidGps，且其路径为E:\work\c++\qt。project创建之后。文件夹结构例如以下：

图3. project初始文件

在上述自己主动生成文件夹下增加文件夹android：

图4. 增加目录android后

目录android里面包括例如以下内容：

图5. 目录android的内容

能够看出，文件夹结构与通过eclipse生成的android工程类似，少了assets。bin，gen，res等文件夹，以及project.properties等文件。

本project可採用百度与高德的库来定位。其相关的jar包分别为BaiduLBS_Android.jar与Android_Location_V1.1.2.jar。这两个包均放入到e:\work\c++\qt\QtAndroid\android\libs。

同一时候。在构建projectQtAndroidGps之后，qt会在路径e:\work\c++\qt\之下自己主动生成文件夹：

E:\work\c++\qt\build-QtAndroidGps-Android_for_armeabi_v7a_GCC_4_8_Qt_5_4_0-Debug，该文件夹包括下面文件：

图6. qt构建project后生成的project文件夹

当中，android-build文件夹包括qt构建出来的androidproject，该project即为完整的androidproject:

图7. qt构建project后生成的androidproject文件夹

能够发现，之前我们人为创建的projecte:\work\c++\qt\QtAndroid\android\里面的文件除了AnroidManifest.xml被整合外，其它文件包含jar包和java文件都被拷贝入：

build-QtAndroidGps-Android_for_armeabi_v7a_GCC_4_8_Qt_5_4_0-Debug。

3.      project文件清单

3.1 E:\work\c++\qt\QtAndroidGps\android\AndroidManifest.xml

......

图8. AndroidManifest.xml

该文件有如上图标注的4个重要点:

①  ->与E:\work\c++\qt\QtAndroidGps\android\src中java文件的包路径相应

②  ->要把百度与高德的包用起来。必须增加Api-key

③  ->相应Activity的类名

④  ->须要开启GPS定位相关的权限

3.2.1 E:\work\c++\qt\QtAndroidGps\mainwindow.h

#ifndef MAINWINDOW_H

#define MAINWINDOW_H

#include <QMainWindow>

#include <QPushButton>

namespace Ui {

class MainWindow;

}

class MainWindow : public QMainWindow

{

    Q_OBJECT

public:

    explicit MainWindow(QWidget *parent = 0);

    ~MainWindow();

protected:

    bool event(QEvent *e);

private:

    Ui::MainWindow *ui;

    QPushButton *btn; // 点击启动GPS

private slots:

    void startGps(); // btn相应的点击槽函数

};

#endif // MAINWINDOW_H

3.2.2 E:\work\c++\qt\QtAndroidGps\mainwindow.cpp

#include "mainwindow.h"

#include "ui_mainwindow.h"

#include <QAndroidJniObject>

#include "CustomEvent.h"

MainWindow::MainWindow(QWidget *parent) :

    QMainWindow(parent),

    ui(new Ui::MainWindow)

{

    ui->setupUi(this);

    btn = new QPushButton("start", this);

    btn->setGeometry(QRect(10, 10, 100, 50));

    connect(btn, SIGNAL(clicked()), this, SLOT(startGps()));

}

MainWindow::~MainWindow()

{

    delete ui;

}

void MainWindow::startGps()

{

    //QAndroidJniObject javaAction = QAndroidJniObject::fromString(url);

    QAndroidJniObject::callStaticMethod<void>( /* 调用java方法，具体情况请參考qt的帮助文档 */

        "com/mtn/mes/GpsService",

        "calledByCpp",

        "()V");

}

bool MainWindow::event(QEvent *e)

{

    if(e->type() == CustomEvent::eventType()){ /* 匹配上自己定义事件类型 */

        e->accept();

        CustomEvent *sce = (CustomEvent*)e;

       //_resultView->setText(sce->m_arg2);

        ui->textBrowser->setText(sce->m_arg2); /* 显示GPS信息 */

        return true;

    }

    return QWidget::event(e);

}

3.3.1 E:\work\c++\qt\QtAndroidGps\CustomEvent.h

#ifndef CUSTOMEVENT_H

#define CUSTOMEVENT_H

#include <QEvent>

#include <QString>

class CustomEvent : public QEvent

{

public:

    CustomEvent(int arg1 = 0, const QString &arg2 = QString());

    ~CustomEvent();

    static Type eventType();

    int m_arg1;

    QString m_arg2;

private:

    static Type m_evType;

};

#endif // CUSTOMEVENT_H

3.3.2 E:\work\c++\qt\QtAndroidGps\CustomEvent.cpp

#include "CustomEvent.h"

QEvent::Type CustomEvent::m_evType = (QEvent::Type)QEvent::None;

CustomEvent::CustomEvent(int arg1, const QString &arg2)

    : QEvent(eventType()), m_arg1(arg1), m_arg2(arg2)

{}

CustomEvent::~CustomEvent()

{

}

QEvent::Type CustomEvent::eventType()

{

    if(m_evType == QEvent::None)

    {

        m_evType = (QEvent::Type)registerEventType(); /* 注冊自己定义事件，返回m_evType值为qt分配的自己定义事件类型 */

    }

    return m_evType;

}

3.4 E:\work\c++\qt\QtAndroidGps\CustomEvent.cpp

#include "mainwindow.h"

#include <QApplication>

#include <QDebug>

#include <jni.h>

#include <QAndroidJniEnvironment>

#include <QAndroidJniObject>

#include "CustomEvent.h"

QObject *main_window = 0;

/* 该函数被java的本地方法调用 */

static void reportGpsInfo(JNIEnv *env, jobject thiz,int result, jstring data)

{

    QString qstrData;

    const char *nativeString = env->GetStringUTFChars(data, 0);

    qstrData = nativeString;

    env->ReleaseStringUTFChars(data, nativeString);

    QCoreApplication::postEvent(main_window, new CustomEvent(result, qstrData)); /* 发送事件(携带GPS信息)给主窗体。自己定义事件类型 */

    qDebug() << qstrData;

}

bool registerNativeMethods()

{

    JNINativeMethod methods[] {

        {"reportGpsInfo", "(ILjava/lang/String;)V", (void*)reportGpsInfo} /* 注冊本地方法，java方可调用，具体信息见qt帮助文档 */

    };

    const char *classname = "com/mtn/mes/ExtendsQtNative";

    jclass clazz;

    QAndroidJniEnvironment env;

    QAndroidJniObject javaClass(classname);

    clazz = env->GetObjectClass(javaClass.object<jobject>());

    qDebug() << "find ExtendsQtNative - " << clazz;

    bool result = false;

    if(clazz) {

        jint ret = env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0]));

        env->DeleteLocalRef(clazz);

        qDebug() << "RegisterNatives return - " << ret;

        result = ret >= 0;

    }

    if(env->ExceptionCheck()) env->ExceptionClear();

    return result;

}

int main(int argc, char *argv[])

{

    QApplication a(argc, argv);

    MainWindow w;

    CustomEvent::eventType(); // 注冊自己定义事件，生成自己定义事件类型

    registerNativeMethods();  // 注冊本地方法

    w.show();

    main_window = qobject_cast<QObject*>(&w);

    return a.exec();

}

3.5 E:\work\c++\qt\QtAndroidGps\android\src\com\mtn\mes\ExtendsQtNative.java

package com.mtn.mes;

import java.lang.String;

public class ExtendsQtNative

{

    public native void reportGpsInfo(int result, String content);

}

3.6 E:\work\c++\qt\QtAndroidGps\android\src\com\mtn\mes\GpsService.java

package com.mtn.mes;

import java.lang.String;

import android.content.Context;

import android.content.Intent;

import android.app.PendingIntent;

import android.os.Handler;

import android.os.Message;

import android.util.Log;

import android.net.ConnectivityManager;

import android.net.NetworkInfo;

import android.net.Uri;

import android.location.Criteria;

import android.provider.Settings;

import android.os.Bundle;

import android.os.Environment;

import java.io.File;

import com.loopj.android.http.AsyncHttpClient;

import com.loopj.android.http.AsyncHttpResponseHandler;

import android.widget.Toast;

import java.util.Date;

import android.location.Location;

import android.location.LocationListener;

import android.location.LocationManager;

import com.amap.api.location.AMapLocation;

import com.amap.api.location.AMapLocationListener;

import com.amap.api.location.LocationManagerProxy;

import com.amap.api.location.LocationProviderProxy;

import com.baidu.location.BDLocation;

import com.baidu.location.BDLocationListener;

import com.baidu.location.LocationClient;

import com.baidu.location.LocationClientOption;

import com.baidu.location.LocationClientOption.LocationMode;

public class GpsService extends org.qtproject.qt5.android.bindings.QtActivity

{

    private static GpsService m_instance;

    private final static String TAG = "GpsService";

    private final static int MSG_STR_GPS_LOC = 0;

    private final static int MSG_RPT_GPS_INF = 1;

    ////////////////////////////////////////////////////////////////

    //                        定位相关

    ////////////////////////////////////////////////////////////////

    private LocationManagerProxy aMapManager;

    public GpsService(){

        m_instance = this;

    }

    public static void calledByCpp() {

        System.out.println("[0]hello world!");

        Message msg = new Message();

        msg.what = MSG_STR_GPS_LOC;

        m_instance.handler.sendMessage(msg); // 消息触发，启动GPS定位

        //m_instance.handler.sendEmptyMessage(0); // 消息触发。启动GPS定位

    }

    public static void calledByCpp(int arg0) {

         System.out.println("[1]hello world!");

    }

    private void startAmap() {

        aMapManager = LocationManagerProxy.getInstance(this);

        /*

         * mAMapLocManager.setGpsEnable(false);

         * 1.0.2版本号新增方法，设置true表示混合定位中包括gps定位，false表示纯网络定位，默认是true Location

         * API定位採用GPS和网络混合定位方式

         * ，第一个參数是定位provider，第二个參数时间最短是2000毫秒，第三个參数距离间隔单位是米，第四个參数是定位监听者

         */

        aMapManager.requestLocationUpdates(LocationProviderProxy.AMapNetwork, 2000, 10, mAMapLocationListener);

    }

    private AMapLocationListener mAMapLocationListener = new AMapLocationListener() {

        @Override

        public void onStatusChanged(String provider, int status, Bundle extras) {

        }

        @Override

        public void onProviderEnabled(String provider) {

        }

        @Override

        public void onProviderDisabled(String provider) {

        }

        @Override

        public void onLocationChanged(Location location) {

        }

        @Override

        public void onLocationChanged(AMapLocation location) {

            if (location != null) {

                Double geoLat = location.getLatitude();

                Double geoLng = location.getLongitude();

                String cityCode = "";

                String desc = "";

                Bundle locBundle = location.getExtras();

                if (locBundle != null) {

                    cityCode = locBundle.getString("citycode");

                    desc = locBundle.getString("desc");

                }

                String str = (

                "location ok:(" + geoLng + "," + geoLat + ")"+

                "\nAccuracy   :" + location.getAccuracy() + "Meter" +

                "\nPositioning:" + location.getProvider() +

                "\nPositioning time:" + new Date(location.getTime()).toLocaleString() +

                "\nCity coding :" + cityCode +

                "\nLocation Description:" + desc +

                "\nProvince:" + location.getProvince() +

                "\nCity:" + location.getCity() +

                "\nDistrict (county):" + location.getDistrict() +

                "\nRegional Coding:" + location.getAdCode());

                //Toast.makeText(getApplicationContext(), "高德定位\n" + str, Toast.LENGTH_SHORT).show();

                // 发送位置信息到handler, hander处再转发给Qt

                Message msg = new Message();

                Bundle data = new Bundle();

                data.putString("value", str);

                msg.setData(data);

                msg.what = MSG_RPT_GPS_INF;

                handler.sendMessage(msg);

            }

        }

    };

    private Handler handler = new Handler() {

        @Override

        public void handleMessage(Message msg) {

            switch(msg.what) {

               case MSG_STR_GPS_LOC: // 消息类型为启动GPS定位

                   m_instance.startAmap();

               break;

               case MSG_RPT_GPS_INF: // 消息类型为上送GSP信息

                   ExtendsQtNative  m_nativeNotify = new ExtendsQtNative();

                   Bundle data = msg.getData();

                   System.out.println(data.getString("value"));

                   m_nativeNotify.reportGpsInfo(0, data.getString("value")); // 掉用c++方法

               break;

               default:

                   System.out.println("msg type error!");

               break;

            }

        }

    };

}

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