android學習筆記（二）map

連續幾天調試，終於可以讓自己的map程式顯示出地圖了，經驗積累如下：

 

地圖顯示需要mapview類，該類應放在mapactivity中，controller則可以控制地圖的伸縮大小（從mapview中得來）。

當然首先我們必須保證申請到apikey，具體資訊可參考

http://code.google.com/intl/zh-CN/android/add-ons/google-apis/maps-overview.html

先來看下布局檔案：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/maplayout"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent" >    <com.google.android.maps.MapViewandroid:id="@+id/viewMap"android:enabled="true"android:clickable="true"android:layout_width="fill_parent"android:layout_height="fill_parent"android:apiKey="0shqezR5L4dW47pyzE4RxOTIOV1lqoP6uInPQGw"/><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    ><TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="@string/lat" android:id="@+id/textView1"></TextView><EditText android:text="EditText" android:layout_height="wrap_content" android:layout_width="wrap_content" android:id="@+id/latitude"></EditText><TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="@string/lon" android:id="@+id/textView2"></TextView><EditText android:text="EditText" android:layout_height="wrap_content" android:layout_width="wrap_content" android:id="@+id/longitude"></EditText><Button android:id="@+id/showmap" android:text="Button" android:layout_height="wrap_content" android:layout_width="wrap_content"></Button></LinearLayout></RelativeLayout>

將apikey放入代碼中，注意在main.xml這個布局檔案中，mapview標籤需用全稱，如

<com.google.android.maps.MapViewandroid:id="@+id/viewMap"android:enabled="true"android:clickable="true"android:layout_width="fill_parent"android:layout_height="fill_parent"android:apiKey="0shqezR5L4dW47pyzE4RxOTIOV1lqoP6uInPQGw"/>

然後manifest.xml檔案中<application>標籤下添加<uses-library android:name="com.google.android.maps" />，注意要添加

 

到<application>下（我開始一時大意，添加到了<activity>下）

 

接下來需要設定程式存取權限，

<manifest>標籤下添加

<uses-permission android:name="android.permission.INTERNET" />

那麼完整的manifest.xml檔案如下：

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"      package="com.test"      android:versionCode="1"      android:versionName="1.0">      <uses-permission android:name="android.permission.INTERNET" />    <application android:icon="@drawable/icon" android:label="@string/app_name">        <activity android:name=".MapTest"                  android:label="@string/app_name">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity><uses-library android:name="com.google.android.maps" />    </application></manifest>

再貼上java檔案：

package com.test;import com.google.android.maps.*;import android.app.Activity;import android.os.Bundle;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.*;public class MapTest extends MapActivity {private MapView viewMap;private Button showbutton;private EditText address_lat;private EditText address_lon;private MapController controller;private double lat = 25.040225;private double lon = 121.52374;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        viewMap = (MapView)findViewById(R.id.viewMap);        showbutton = (Button)findViewById(R.id.showmap);        address_lat = (EditText)findViewById(R.id.latitude);        address_lon = (EditText)findViewById(R.id.longitude);        controller = viewMap.getController();        viewMap.setSatellite(false);        viewMap.setStreetView(true);        controller.setZoom(17);                   refreshMap();                showbutton.setOnClickListener(new OnClickListener(){        @Overridepublic void onClick(View v) {// TODO Auto-generated method stubboolean input_is_ok = inputCheck();if(input_is_ok){lat = Double.parseDouble(address_lat.getText().toString());lon = Double.parseDouble(address_lon.getText().toString());refreshMap();}else{//showDialog(1);}}                });    }        private boolean inputCheck()    {    if(address_lat.getText().toString().equals("") || address_lon.getText().toString().equals(""))    return false;    else    return true;    }    private void refreshMap() {    GeoPoint point = new GeoPoint((int)(lat * 1e6), (int)(lon * 1e6));    viewMap.displayZoomControls(true);    controller.animateTo(point);    controller.setZoom(17);    }@Overrideprotected boolean isRouteDisplayed() {// TODO Auto-generated method stubreturn false;}}

如果你想要實現一個簡單的地圖縮放功能，可以使用mapview中的setBuiltInZoomControls(boolean on)

如：

viewmap.setBuiltInZoomControls(true);

這樣我們可以得到一個控制縮放的控制項。

涉及到GPS定位的問題，還需要用到其他類。

Location，該對象包含地理位置資訊。在跟蹤位置的過程中，我們需要即時的得到Location對象。

通過LocationManager對象中的

public

Location getLastKnownLocation
(String provider)方法我們可以得到當前的location對象。參數provider是locationprovider的名字。LocationProvider根據我現在的理解，該對象指的應該是定位元模式，我們知道定位元模式一般有gps定位，基站定位，network定位，WIFI定位等，android提供給我們兩種provider，分別是：LocationManager.NETWORK_PROVIDER和LocationManager.GPS_PROVIDER
前者用於移動網路中擷取位置，精度較低但速度很快，後者使用GPS進行定位，精度很高但一般需要10-60秒時間才能開始第1次定位，如果是在室內則基本上無法定位。

當然，我們也可以重寫自己的provider。
舉一個簡單的栗子：

package com.test;import java.util.List;import com.google.android.maps.*;import android.app.Activity;import android.content.Context;import android.location.*;import android.os.Bundle;import android.util.Log;import android.widget.*;public class MapUpdate extends MapActivity {private MapView viewmap;private LocationManager managerlocation;private Location currentLocation;private Criteria ct;private MapController mcontrol;private String locpro;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        viewmap = (MapView) findViewById(R.id.viewMap);        mcontrol = viewmap.getController();        managerlocation = (LocationManager)getSystemService(Context.LOCATION_SERVICE);                viewmap.setBuiltInZoomControls(true);                  //通過criteria對象，設定位置資料的標準，以便系統根據需要為我們選取合適的provider        ct = new Criteria();        ct.setAccuracy(Criteria.ACCURACY_FINE);        ct.setAltitudeRequired(false);        ct.setBearingRequired(false);        ct.setCostAllowed(true);        ct.setPowerRequirement(Criteria.POWER_LOW);                currentLocation = getCurrentLocation(managerlocation, ct);                if (currentLocation == null)        {        Log.d("test", "currentLocation is null");        }        else        {        refreshMylocation(currentLocation);        }                LocationListener lolis = new LocationListener(){@Overridepublic void onLocationChanged(Location location) {// TODO Auto-generated method stubrefreshMylocation(location);}@Overridepublic void onProviderDisabled(String provider) {// TODO Auto-generated method stub}@Overridepublic void onProviderEnabled(String provider) {// TODO Auto-generated method stub}@Overridepublic void onStatusChanged(String provider, int status,Bundle extras) {// TODO Auto-generated method stub}                };                managerlocation.requestLocationUpdates(locpro, 5000, 10, lolis);    }        private void refreshMylocation(Location cl) {// TODO Auto-generated method stubdouble lat = cl.getLatitude() * 1e6;double lon = cl.getLongitude() * 1e6;GeoPoint gp = new GeoPoint((int)lat, (int)lon);RouteOverlay routepoint = new RouteOverlay(gp);viewmap.getOverlays().add(routepoint);mcontrol.animateTo(gp);}private Location getCurrentLocation(LocationManager lm, Criteria ct){    Location cl = null;        locpro = lm.getBestProvider(ct, true);        //Log.d("providername", locpro);        try    {    cl = lm.getLastKnownLocation(locpro);    }catch(Exception e){    Log.d("LocationException", e.toString() + " ");    e.printStackTrace();    }        if (locpro == null)    {    Log.d("providertest", "locationprovider is null");    }    else    {    Log.d("providertest", "locationprovider is ok");    }        if(cl == null)    {    Log.d("LocationTest", "location is null");    }        return cl;        }@Overrideprotected boolean isRouteDisplayed() {// TODO Auto-generated method stubreturn false;}}