Android之PowerManager&BatteryManager

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-permission android: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://blog.csdn.net/jerehedu

版权声明：本文版权归烟台杰瑞教育科技有限公司和CSDN共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。

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