简单实现的一个显示电池的电量的View，具体看代码

public class MainActivity extends Activity {

BatteryView mBatteryView;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

mBatteryView = (BatteryView) findViewById(R.id.battery_view);

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

getMenuInflater().inflate(R.menu.main, menu);

return true;

}

@Override

protected void onResume() {

super.onResume();

register();

}

@Override

protected void onPause() {

super.onPause();

unregister();

}

private void register() {

registerReceiver(batteryChangedReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));

}

private void unregister() {

unregisterReceiver(batteryChangedReceiver);

}

// 接受广播

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;

Log.d("Deom", "电池电量：:" + power);

mBatteryView.setPower(power);

}

}

};

}

public class BatteryView extends View{

private int mPower = 100;

public BatteryView(Context context) {

super(context);

}

public BatteryView(Context context, AttributeSet attrs) {

super(context, attrs);

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

int battery_left = 0;

int battery_top = 0;

int battery_width = 25;

int battery_height = 15;

int battery_head_width = 3;

int battery_head_height = 3;

int battery_inside_margin = 3;

//先画外框

Paint paint = new Paint();

paint.setColor(Color.BLACK);

paint.setAntiAlias(true);

paint.setStyle(Style.STROKE);

Rect rect = new Rect(battery_left, battery_top,

battery_left + battery_width, battery_top + battery_height);

canvas.drawRect(rect, paint);

float power_percent = mPower / 100.0f;

Paint paint2 = new Paint(paint);

paint2.setStyle(Style.FILL);

//画电量

if(power_percent != 0) {

int p_left = battery_left + battery_inside_margin;

int p_top = battery_top + battery_inside_margin;

int p_right = p_left - battery_inside_margin + (int)((battery_width - battery_inside_margin) * power_percent);

int p_bottom = p_top + battery_height - battery_inside_margin * 2;

Rect rect2 = new Rect(p_left, p_top, p_right , p_bottom);

canvas.drawRect(rect2, paint2);

}

//画电池头

int h_left = battery_left + battery_width;

int h_top = battery_top + battery_height / 2 - battery_head_height / 2;

int h_right = h_left + battery_head_width;

int h_bottom = h_top + battery_head_height;

Rect rect3 = new Rect(h_left, h_top, h_right, h_bottom);

canvas.drawRect(rect3, paint2);

}

public void setPower(int power) {

mPower = power;

if(mPower < 0) {

mPower = 0;

}

invalidate();

}

}

效果如下: