Android 绘制电池电量图标（含充电状态）。

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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main2"
    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"
    android:background="@color/colorAccent"
    tools:context="com.example.mybluetooth.Main2Activity">
    <!--电池电量 -->
    <ImageView
        android:id="@+id/image_battery"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginLeft="300dp"
        android:src="@drawable/battery"/>
</RelativeLayout>

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<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >

    <!-- 空的电池 -->
    <item>
        <bitmap android:src="@drawable/battery_empty" />
    </item>
     <!-- 裁剪满的电池图标 -->
    <item android:id="@+id/clip_drawable">
        <clip
            android:clipOrientation="horizontal"
            android:drawable="@drawable/battery_full"
            android:gravity="left" />
    </item>

</layer-list>

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public class Main2Activity extends AppCompatActivity {
    private ClipDrawable clipDrawable;
    private int currentPower = 0;
    private boolean isCharging = false;
    private Handler handler = new Handler();
    private boolean canAnimater;
    private  ImageView imageBattery;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
         imageBattery = (ImageView) findViewById(R.id.image_battery);
        LayerDrawable layerDrawable = (LayerDrawable) imageBattery.getDrawable();
        clipDrawable = (ClipDrawable) layerDrawable.findDrawableByLayerId(R.id.clip_drawable);
    }

    @Override
    protected void onResume() {
        super.onResume();
        canAnimater =true;
        handler.removeCallbacks(chargingRunnable);
        handler.post(chargingRunnable);
        IntentFilter intentFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
        intentFilter.addAction(Intent.ACTION_POWER_CONNECTED);
        intentFilter.addAction(Intent.ACTION_POWER_DISCONNECTED);
        registerReceiver(batteryChangedReceiver, intentFilter);
    }

    @Override
    protected void onPause() {
        super.onPause();
        canAnimater=false;
        unregisterReceiver(batteryChangedReceiver);
        handler.removeCallbacks(chargingRunnable);
    }

    // 电量变化广播
    // TODO 假设进入Activity之前就已经在充电，进入之后无法收到充电的广播
    private BroadcastReceiver batteryChangedReceiver = new BroadcastReceiver() {

        public void onReceive(Context context, Intent intent) {
            if (Intent.ACTION_BATTERY_CHANGED.equals(intent.getAction())) {
                int level = intent.getIntExtra("level", 0);
                int scale = intent.getIntExtra("scale", 100);
                int power = level * 100 / scale;
                currentPower = power;
                clipDrawable.setLevel(calculateLevel(power));
            } else {
                int status = intent.getIntExtra("status", currentPower);

                if (Intent.ACTION_POWER_CONNECTED.equals(intent.getAction())) {
                    isCharging = true;

                } else if (Intent.ACTION_POWER_DISCONNECTED.equals(intent.getAction())) {
                    isCharging = false;
                }

                Toast.makeText(Main2Activity.this, "充电：" + isCharging + "," + status, Toast.LENGTH_SHORT).show();
                if (isCharging) {
                    handler.removeCallbacks(chargingRunnable);
                    handler.post(chargingRunnable);
                }
                //在自定义充电状态的图片时在这里
//                else {
//                    imageBattery.setImageResource(R.drawable.battery_full);
//                }
            }
        }
    };

    private int calculateLevel(int progress) {
        int leftOffest = dip2px(this, 2);
        int powerLength = dip2px(this, 26.5f);// 40 px in hdpi
        int totalLength = dip2px(this, 32.5f);// 49 px in hdpi
        int level = (leftOffest + powerLength * progress / 100) * 10000 / totalLength;
        return level;
    }

    private int dip2px(Context context, float v) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (v * scale + 0.5f);
    }

    private Runnable chargingRunnable = new Runnable() {

        @Override
        public void run() {

            Log.e("test", "isCharging:" + isCharging + ",canAnimater:" + canAnimater);
            if (!isCharging || !canAnimater) {
                return;
            }
           // imageBattery.setImageResource(R.drawable.battery_empty); 充电状态图片

            ValueAnimator animator = ValueAnimator.ofInt(100, currentPower, 100);
            animator.setDuration(1500);
            animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {

                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    int animatedValue = (Integer) animation.getAnimatedValue();
                    clipDrawable.setLevel(calculateLevel(animatedValue));
                }
            });
            animator.addListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationEnd(Animator animation) {
                    if (isCharging && canAnimater) {
                        handler.postDelayed(chargingRunnable, 600);
                    } else {
                        clipDrawable.setLevel(calculateLevel(currentPower));
                    }
                }
            });
            animator.start();
        }
    };
}