Android中常用的系统服务

package com.example.systemservicedemo;

import android.app.Activity;
import android.app.ActivityManager;
import android.content.Context;
import android.media.AudioManager;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Toast;


public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LayoutInflater inflater =(LayoutInflater) MainActivity.this.getSystemService(LAYOUT_INFLATER_SERVICE);
        View view =inflater.inflate(R.layout.activity_main,null);
        setContentView(R.layout.activity_main);
    }
    public void doClick(View view){
    	switch (view.getId()) {
		case R.id.network:
			if(isNetWorkConnected(MainActivity.this)==true){
				Toast.makeText(MainActivity.this,"网络已经打开",Toast.LENGTH_SHORT).show();
			}
			else{
				Toast.makeText(MainActivity.this,"网络未连接",Toast.LENGTH_SHORT).show();
			}
			break;
		case R.id.enableOrDisable:
			WifiManager wifiManager=(WifiManager) MainActivity.this.getSystemService(WIFI_SERVICE);
			if(wifiManager.isWifiEnabled()){
				wifiManager.setWifiEnabled(false);
				Toast.makeText(MainActivity.this,"WIFI已关闭",Toast.LENGTH_SHORT).show();
			}else {
				wifiManager.setWifiEnabled(true);
				Toast.makeText(MainActivity.this,"WIFI已打开",Toast.LENGTH_SHORT).show();
			}
			break;
			case R.id.getvoice:
				AudioManager audioManager=(AudioManager) MainActivity.this.getSystemService(AUDIO_SERVICE);
				int max=audioManager.getStreamMaxVolume(AudioManager.STREAM_SYSTEM);
				int current=audioManager.getStreamVolume(AudioManager.STREAM_RING);
				Toast.makeText(MainActivity.this,"当前最大音量："+max+"当前音量："+current,Toast.LENGTH_SHORT).show();
				break;
			case R.id.getProcessPakage:
				ActivityManager activityManager=(ActivityManager) MainActivity.this.getSystemService(ACTIVITY_SERVICE);
				String pakageName=activityManager.getRunningTasks(1).get(0).topActivity.getPackageName();
				Toast.makeText(MainActivity.this,"当前运行的包名："+pakageName,Toast.LENGTH_SHORT).show();
				break;
		default:
			break;
		}
    }
    public boolean isNetWorkConnected(Context context){
    	if(context!=null){
    		ConnectivityManager manager=(ConnectivityManager) context.getSystemService(CONNECTIVITY_SERVICE);
    		NetworkInfo networkInfo=manager.getActiveNetworkInfo();
    		if(networkInfo!=null){
    			return networkInfo.isAvailable();
    		}
    	}
    	return false;
    }
}

<RelativeLayout 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: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="com.example.systemservicedemo.MainActivity" >

    <Button
        android:id="@+id/network"
        android:onClick="doClick"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:text="判断网络是否连接" />

    <Button
        android:id="@+id/enableOrDisable"
        android:onClick="doClick"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/network"
        android:layout_alignRight="@+id/network"
        android:layout_below="@+id/network"
        android:text="开关WIFI" />

    <Button
        android:id="@+id/getvoice"
        android:onClick="doClick"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/enableOrDisable"
        android:layout_alignRight="@+id/enableOrDisable"
        android:layout_below="@+id/enableOrDisable"
        android:text="获取系统音量" />

    <Button
        android:id="@+id/getProcessPakage"
        android:onClick="doClick"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/getvoice"
        android:layout_alignRight="@+id/getvoice"
        android:layout_below="@+id/getvoice"
        android:text="获取当前运行程序包名" />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.systemservicedemo"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="15"
        android:targetSdkVersion="20" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
    <uses-permission android:name="android.permission.GET_TASKS" /><uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
    

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>