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[操作系统]Android之PowerManagerBatteryManager


  PowerManager是Android平台中用于管理控制设备电源状态、重启、休眠状态、唤醒等,使用该API会影响到电池的待机时间,所以无非必要,一般不要使用。

  在PowerManager中有几个比较重要的公共方法,具体如下:

  方法goToSleep、reboot、userActivity需要用到如下权限:

<uses-permission android:name="android.permission.REBOOT"/>
<uses-permissionandroid:name="android.permission.DEVICE_POWER"/>

  而这两个权限只有系统App才可使用。

  最重要的方法还是newWakeLock,通过该方法,我们可以获取一个WakeLock对象,通过该对象我们可以控制设备电源的状态。方法的第一个参数flags用于指示获取哪种WakeLock,不同的Lock对cpu、屏幕、键盘灯有不同的影响,flag的值如下:

下面我们通过一个案例来说明WakeLock的用法,具体代码如下:

public class PowerManagerActivity extends ActionBarActivity {  private PowerManager powerManager;  private PowerManager.WakeLock wakeLock;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_power_manager);    powerManager = (PowerManager)getSystemService(Context.POWER_SERVICE);  }    private void acquireWakeLock(){    wakeLock = powerManager.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK,"wakelock");    if(wakeLock!=null)      wakeLock.acquire();  }  private void releaseWakeLock(){    if(wakeLock!=null)      wakeLock.release();  }  @Override  protected void onResume() {    super.onResume();    acquireWakeLock();  }  @Override  protected void onPause() {    super.onPause();    releaseWakeLock();  }}

  使用该方法需要用到如下权限:

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

  代码比较简单,在获取WakeLock的时候我们使用了PowerManager.SCREEN_BRIGHT_WAKE_LOCK,该flag表明cpu保持运行,屏幕保持常亮。同时注意WakeLock的acquire方法和release方法要成对使用,在这里利用了Activity的生命周期方法。
  还要注意的是WakeLock是Activity级别的不是针对整个Application的。
  要想获取电池信息比如状态、健康信息、电池容量等,我们可以通过注册一个广播接收者用来接收Intent.ACTION_BATTERY_CHANGED广播即可,当电池发送变化的时候,系统就会发出该广播。Android提供了BatteryManager类,该类主要提供了一些常量,用于从广播的Intent中提取相关的数据,常量列表如下:

定义一个广播接收者,用于检测电池状态的变化,关键代码如下:
private class BattaryReceiver extends BroadcastReceiver {  @Override  public void onReceive(Context context, Intent intent) {  if(intent.getAction().equals(Intent.ACTION_BATTERY_CHANGED)){    //电池状态    int status = intent.getIntExtra(BatteryManager.EXTRA_STATUS,0);    String statusString = "";    switch (status){      case BatteryManager.BATTERY_STATUS_FULL:        statusString="full";        break;      case BatteryManager.BATTERY_STATUS_CHARGING:        statusString="charging";        break;      case BatteryManager.BATTERY_STATUS_DISCHARGING:        statusString="discharging";        break;      case BatteryManager.BATTERY_STATUS_UNKNOWN:        statusString="unknown";        break;      case BatteryManager.BATTERY_STATUS_NOT_CHARGING:        statusString="not charging";        break;    }    //    boolean present= intent.getBooleanExtra(BatteryManager.EXTRA_PRESENT,false);    //integer field containing the current battery level,    int curlevel = intent.getIntExtra(BatteryManager.EXTRA_LEVEL,0);    // integer containing the maximum battery level    int maxLevel = intent.getIntExtra(BatteryManager.EXTRA_SCALE,0);    //String describing the technology of the current battery    String technology = intent.getStringExtra(BatteryManager.EXTRA_TECHNOLOGY);    //integer containing the current health constant    int health = intent.getIntExtra(BatteryManager.EXTRA_HEALTH,0);    String healthStr = "";    switch (health){      case BatteryManager.BATTERY_HEALTH_COLD:        healthStr="cold";        break;      case BatteryManager.BATTERY_HEALTH_DEAD:        healthStr="dead";        break;      case BatteryManager.BATTERY_HEALTH_GOOD:        healthStr="good";        break;      case BatteryManager.BATTERY_HEALTH_OVER_VOLTAGE:        healthStr="voer voltage";        break;      case BatteryManager.BATTERY_HEALTH_UNKNOWN:        healthStr="unknown";        break;      case BatteryManager.BATTERY_HEALTH_UNSPECIFIED_FAILURE:        healthStr="unspecified failure";        break;    }    //integer containing the resource ID of a small status bar icon indicating the current battery state    int smallIcon = intent.getIntExtra(BatteryManager.EXTRA_ICON_SMALL,0);    //integer indicating whether the device is plugged in to a power source; 0 means it is on battery,    // other constants are different types of power sources    int plugged = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED,0);    String pluggedStr="";    switch (plugged){      case BatteryManager.BATTERY_PLUGGED_AC:        pluggedStr="AC";        break;      case BatteryManager.BATTERY_PLUGGED_USB:        pluggedStr="USB";        break;      case BatteryManager.BATTERY_PLUGGED_WIRELESS:        pluggedStr="wireless";        break;    }    // integer containing the current battery temperature.    int temperature= intent.getIntExtra(BatteryManager.EXTRA_TEMPERATURE,0);    // integer containing the current battery voltage level.    int voltage = intent.getIntExtra(BatteryManager.EXTRA_VOLTAGE,0);    StringBuilder sb = new StringBuilder("status:");    sb.append(statusString);    sb.append("\n");    sb.append("present:").append(present);    sb.append("\n");    sb.append("level:").append(curlevel);    sb.append("\n");    sb.append("maxLevel:").append(maxLevel);    sb.append("\n");    sb.append("technology:").append(technology);    sb.append("\n");    sb.append("health:").append(healthStr);    sb.append("\n");    sb.append("icon:").append(smallIcon);    sb.append("\n");    sb.append("plugged:").append(pluggedStr);    sb.append("\n");    sb.append("temperature:").append(temperature);    sb.append("\n");    sb.append("voltage:").append(voltage);    sb.append("\n");    Message msg= mHandler.obtainMessage(1);    msg.obj = sb.toString();    mHandler.sendMessage(msg);  }}}

主要接收该广播需要用到权限:

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

  案例运行结果如下:

 

作者:杰瑞教育
出处:http://www.cnblogs.com/jerehedu/ 
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