android学习笔记（二）map
连续几天调试，终于可以让自己的map程序显示出地图了，经验积累如下：
地图显示需要mapview类，该类应放在mapactivity中，controller则可以控制地图的伸缩大小（从mapview中得来）。
当然首先我们必须保证申请到apikey，具体信息可参考
http://code.google.com/intl/zh-CN/android/add-ons/google-apis/maps-overview.html
先来看下布局文件：
<?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.MapView
android: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>
将apikey放入代码中，注意在main.xml这个布局文件中，mapview标签需用全称，如
<com.google.android.maps.MapView android:id="@+id/viewMap" android:enabled="true" android:clickable="true" android:layout_width="fill_parent" android:layout_height="fill_parent" android:apiKey="0shqezR5L4dW47pyzE4RxOTIOV1lqoP6uInPQGw"/>
然后manifest.xml文件中<application>标签下添加<uses-library android:name="com.google.android.maps" />，注意要添加
到<application>下（我开始一时大意，添加到了<activity>下）
接下来需要设置程序访问权限，
<manifest>标签下添加
<uses-permission android:name="android.permission.INTERNET" />
那么完整的manifest.xml文件如下：
<?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>
再贴上java文件：
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(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
boolean 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);
}
@Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
}
如果你想要实现一个简单的地图缩放功能，可以使用mapview中的setBuiltInZoomControls(boolean on)
如：
viewmap.setBuiltInZoomControls(true);
这样我们可以得到一个控制缩放的控件。
涉及到GPS定位的问题，还需要用到其他类。
Location，该对象包含地理位置信息。在跟踪位置的过程中，我们需要实时的得到Location对象。
通过LocationManager对象中的
public Location getLastKnownLocation (String provider)方法我们可以得到当前的location对象。
参数provider是locationprovider的名字。
LocationProvider根据我现在的理解，该对象指的应该是定位模式，我们知道定位模式一般有gps定位，基站定位，
network定位，WIFI定位等，android提供给我们两种provider，分别是：LocationManager.NETWORK_PROVIDER和LocationManager.GPS_PROVIDER
前者用于移动网络中获取位置，精度较低但速度很快，后者使用GPS进行定位，精度很高但一般需要10-60秒时间才能开始第1次定位，如果是在室内则基本上无法定位。
当然，我们也可以重写自己的provider。
举一个简单的栗子：
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);
//通过criteria对象，设置位置数据的标准，以便系统根据需要为我们选取合适的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(){
@Override
public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
refreshMylocation(location);
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public 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 stub
double 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;
}
@Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
}