Android中GPS定位的简单应用

在Android中通过GPS获得当前位置，首先要获得一个LocationManager实例，通过该实例的getLastKnownLocation()方法获得第一个的位置，该方法的说明如下：

void android.location.LocationManager.requestLocationUpdates(String provider, long minTime, float minDistance, LocationListener listener)

provider即定位方式，可以采用GPS定位(LocationManager.GPS_PROVIDER)或者网络定位(LocationManager.NETWORK_PROVIDER)，本文是GPS定位，因此使用LocationManager.GPS_PROVIDER。minTime是位置更新的间隔时间。listener是位置改变的监听器，自己定义一个LocationListener()，重写onLocationChanged()，加入位置改变时的动作。

布局文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/txt_time"
        style="@style/my_text"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="时间:" />

    <TextView
        android:id="@+id/txt_lat"
        style="@style/my_text"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="经度:" />

    <TextView
        android:id="@+id/txt_lng"
        style="@style/my_text"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="纬度:" />

</LinearLayout>

MainActivity.java文件：

package com.hzhi.my_gps;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;

import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.content.Context;
import android.view.Menu;
import android.widget.TextView;

public class MainActivity extends Activity {
	
	TextView txt_time;
	TextView txt_lat;
	TextView txt_lng;
	LocationManager lom;
	Location loc;
	Double lat;
	Double lng;
	SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	Date now;
	String str_date;
	Timer timer;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		get_con();
		get_gps();
		
		timer = new Timer(true);
		timer.schedule(task, 0, 1000);
		
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}
	
	public void get_gps(){
		
		lom = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
		loc = lom.getLastKnownLocation(LocationManager.GPS_PROVIDER);
		
		if (loc != null) {
		    lat = loc.getLatitude();
		    lng = loc.getLongitude();
		    txt_lat.setText("纬度:" + String.valueOf(lat));
		    txt_lng.setText("经度:" + String.valueOf(lng));
		}
		else{
		    txt_lat.setText("纬度:未知" );
		    txt_lng.setText("经度:未知" );
		}
		
        Criteria criteria = new Criteria();
        criteria.setAccuracy(Criteria.ACCURACY_FINE);
        criteria.setAltitudeRequired(false);
        criteria.setBearingRequired(false);
        criteria.setCostAllowed(true);
        criteria.setPowerRequirement(Criteria.POWER_LOW);
        String provider = lom.getBestProvider(criteria, true);
		
		lom.requestLocationUpdates(provider, 1000, 10, los);
		
	}
	
	LocationListener los = new LocationListener(){
		
		public void onLocationChanged(Location location){
			
			if (location != null) {
			    lat = location.getLatitude();
			    lng = location.getLongitude();
			    txt_lat.setText("纬度:" + String.valueOf(lat));
			    txt_lng.setText("经度:" + String.valueOf(lng));
			}
			else{
			    txt_lat.setText("纬度:未知" );
			    txt_lng.setText("经度:未知" );
			}
			
		};
		
    	public void onProviderDisabled(String provider){
    	
    	};
    	
    	public void onProviderEnabled(String provider){ };
    	
    	public void onStatusChanged(String provider, int status,
    	Bundle extras){ };
		
	};
	
	// 获取控件
	public void get_con(){
		
		txt_time = (TextView) findViewById(R.id.txt_time);
		txt_lat = (TextView) findViewById(R.id.txt_lat);
		txt_lng = (TextView) findViewById(R.id.txt_lng);
		
	}
	
	Handler handler = new Handler(){
		
		public void handleMessage(Message msg){
			switch (msg.what){
			case 1:
				get_time();
				break;
			}
		}
		
	};
	
	TimerTask task = new TimerTask(){  
	      public void run() {  
	          Message message = new Message();      
	          message.what = 1;      
	          handler.sendMessage(message);   
	   }  
	};
	
	// 获取时间
	public void get_time(){
		
		now = new Date(System.currentTimeMillis());
		str_date = formatter.format(now);
		txt_time.setText("时间:" + str_date);
		
	}

}

在AndroidManifest.xml文件中加入权限：

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

运行前先打开GPS卫星，运行结果：

由于在室内，并且手机质量不好，没获取出来，在室外是可以获取的。