android 广播监控手机电量_广播接收者监听电量小于15时

问题很简单 直接给出代码

<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"
    tools:context=".MainActivity" >
 
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:orientation="vertical" >
 
        <TextView
            android:id="@+id/tv_cell"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="电池电量"
            android:textColor="#000000"
            android:layout_margin="10dp"
            android:textSize="18dp" />
    </LinearLayout>
 
</RelativeLayout>

监听需要权限<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

package cn.itcast.BatteryChecker;
 
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.net.NetworkInfo.State;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;
 
public class MainActivity extends Activity {
 
	private TextView tv_cell;
	private BatteryReceiver batteryReceiver;
 
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
 
		tv_cell = (TextView) findViewById(R.id.tv_cell);
		// 注册广播接受者java代码
		IntentFilter intentFilter = new IntentFilter(
				Intent.ACTION_BATTERY_CHANGED);
		batteryReceiver = new BatteryReceiver();
		// 注册receiver
		registerReceiver(batteryReceiver, intentFilter);
	}
 
	/**
	 * 广播接受者
	 */
	private class BatteryReceiver extends BroadcastReceiver {
		@Override
		public void onReceive(Context context, Intent intent) {
			if (Intent.ACTION_BATTERY_CHANGED.equals(intent.getAction())) {
				int level = intent.getIntExtra("level", 0);
				tv_cell.setText("电池电量为" + level + "%");
 
				if (level < 15) {
					Toast.makeText(MainActivity.this, "电池电量不足15%，请及时充电", 0)
							.show();
				}
			}
		}
 
	}
 
	@Override
	protected void onDestroy() {
		super.onDestroy();
		unregisterReceiver(batteryReceiver);
	}
}