转载出处：http://blog.csdn.net/donkor_/article/details/53175903
前言：本文提供一个Android开发中可能会使用到电池控件view，有水平和垂直两个方向，同时根据电池电量更改电池中的电量颜色。首先看下效果图： 
以下为实现过程：
1.在values目录下新建attrs,添加所需要的名字啊，包括可以更改的电池排列方向，电池颜色，电池电量。
<declare-styleable name="Battery">
<attr name="batteryOrientation">
<enum name="horizontal" value="0"/>
<enum name="vertical" value="1"/>
</attr>
<attr name="batteryColor" format="color"/>
<attr name="batteryPower" format="integer"/>
</declare-styleable>2.创建BatteryView文件继承View，在View的构造方法中，获取我们需要的自定义样式。重写onMesure，onDraw方法。
package com.donkor.demo;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;
/**
* @author donkor
* 自定义水平\垂直电池控件
*/
public class BatteryView extends View {
private int mPower = 100;
private int orientation;
private int width;
private int height;
private int mColor;
public BatteryView(Context context) {
super(context);
}
public BatteryView(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.Battery);
mColor = typedArray.getColor(R.styleable.Battery_batteryColor, 0xFFFFFFFF);
orientation = typedArray.getInt(R.styleable.Battery_batteryOrientation, 0);
mPower = typedArray.getInt(R.styleable.Battery_batteryPower, 100);
width = getMeasuredWidth();
height = getMeasuredHeight();
/**
* recycle() :官方的解释是：回收TypedArray，以便后面重用。在调用这个函数后，你就不能再使用这个TypedArray。
* 在TypedArray后调用recycle主要是为了缓存。当recycle被调用后，这就说明这个对象从现在可以被重用了。
* TypedArray 内部持有部分数组，它们缓存在Resources类中的静态字段中，这样就不用每次使用前都需要分配内存。
*/
typedArray.recycle();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
//对View上的內容进行测量后得到的View內容占据的宽度
width = getMeasuredWidth();
//对View上的內容进行测量后得到的View內容占据的高度
height = getMeasuredHeight();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//判断电池方向 horizontal: 0 vertical: 1
if (orientation == 0) {
drawHorizontalBattery(canvas);
} else {
drawVerticalBattery(canvas);
}
}
/**
* 绘制水平电池
*
* @param canvas
*/
private void drawHorizontalBattery(Canvas canvas) {
Paint paint = new Paint();
paint.setColor(mColor);
paint.setStyle(Paint.Style.STROKE);
float strokeWidth = width / 20.f;
float strokeWidth_2 = strokeWidth / 2;
paint.setStrokeWidth(strokeWidth);
RectF r1 = new RectF(strokeWidth_2, strokeWidth_2, width - strokeWidth - strokeWidth_2, height - strokeWidth_2);
//设置外边框颜色为黑色
paint.setColor(Color.BLACK);
canvas.drawRect(r1, paint);
paint.setStrokeWidth(0);
paint.setStyle(Paint.Style.FILL);
//画电池内矩形电量
float offset = (width - strokeWidth * 2) * mPower / 100.f;
RectF r2 = new RectF(strokeWidth, strokeWidth, offset, height - strokeWidth);
//根据电池电量决定电池内矩形电量颜色
if (mPower < 30) {
paint.setColor(Color.RED);
}
if (mPower >= 30 && mPower < 50) {
paint.setColor(Color.BLUE);
}
if (mPower >= 50) {
paint.setColor(Color.GREEN);
}
canvas.drawRect(r2, paint);
//画电池头
RectF r3 = new RectF(width - strokeWidth, height * 0.25f, width, height * 0.75f);
//设置电池头颜色为黑色
paint.setColor(Color.BLACK);
canvas.drawRect(r3, paint);
}
/**
* 绘制垂直电池
*
* @param canvas
*/
private void drawVerticalBattery(Canvas canvas) {
Paint paint = new Paint();
paint.setColor(mColor);
paint.setStyle(Paint.Style.STROKE);
float strokeWidth = height / 20.0f;
float strokeWidth2 = strokeWidth / 2;
paint.setStrokeWidth(strokeWidth);
int headHeight = (int) (strokeWidth + 0.5f);
RectF rect = new RectF(strokeWidth2, headHeight + strokeWidth2, width - strokeWidth2, height - strokeWidth2);
canvas.drawRect(rect, paint);
paint.setStrokeWidth(0);
float topOffset = (height - headHeight - strokeWidth) * (100 - mPower) / 100.0f;
RectF rect2 = new RectF(strokeWidth, headHeight + strokeWidth + topOffset, width - strokeWidth, height - strokeWidth);
paint.setStyle(Paint.Style.FILL);
canvas.drawRect(rect2, paint);
RectF headRect = new RectF(width / 4.0f, 0, width * 0.75f, headHeight);
canvas.drawRect(headRect, paint);
}
/**
* 设置电池电量
*
* @param power
*/
public void setPower(int power) {
this.mPower = power;
if (mPower < 0) {
mPower = 100;
}
invalidate();//刷新VIEW
}
/**
* 设置电池颜色
*
* @param color
*/
public void setColor(int color) {
this.mColor = color;
invalidate();
}
/**
* 获取电池电量
*
* @return
*/
public int getPower() {
return mPower;
}
}3.在布局文件中声明我们的VIEW
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical"
>
<com.donkor.demo.BatteryView
android:id="@+id/horizontalBattery"
android:layout_width="30dp"
android:layout_marginBottom="30dp"
android:layout_height="14dp"
android:layout_marginTop="5dp"
android:background="#fff"
android:gravity="center"
app:batteryPower="70"
app:batteryColor="@android:color/black"
app:batteryOrientation="horizontal"
/>
<com.donkor.demo.BatteryView
android:id="@+id/verticalBattery"
android:layout_width="14dp"
android:layout_height="25dp"
android:layout_marginTop="5dp"
android:background="#fff"
android:gravity="center"
app:batteryOrientation="vertical"
/>
</LinearLayout>4.在Activity中加入一个线程，使电池无限循环，营造出一个正在充电的状态，这样就大功告成。
package com.donkor.demo;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import java.util.Timer;
import java.util.TimerTask;
/**
* @author donkor
*/
public class MainActivity extends Activity {
private BatteryView horizontalBattery, verticalBattery;
private int power;
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 0:
horizontalBattery.setPower(power += 5);
if (power == 100) {
power = 0;
}
break;
default:
break;
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
horizontalBattery = (BatteryView) findViewById(R.id.horizontalBattery);
verticalBattery = (BatteryView) findViewById(R.id.verticalBattery);
verticalBattery.setColor(Color.BLACK);
verticalBattery.setPower(85);
new Timer().schedule(new TimerTask() {
@Override
public void run() {
mHandler.sendEmptyMessage(0);
}
}, 0, 100);
}
}