【移动应用开发技术】怎么在Android中通过自定义控件实现时钟功能

【移动应用开发技术】怎么在Android中通过自定义控件实现时钟功能

这篇文章将为大家详细讲解有关怎么在Android中通过自定义控件实现时钟功能，文章内容质量较高，因此在下分享给大家做个参考，希望大家阅读完这篇文章后对相关知识有一定的了解。自定义控件的代码（ClockView.java）：package

com.example.clock;

import

java.util.Calendar;

import

java.util.Date;

import

android.content.Context;

import

android.graphics.Canvas;

import

android.graphics.Color;

import

android.graphics.Paint;

import

android.os.Handler;

import

android.os.Looper;

import

android.os.Message;

import

android.util.AttributeSet;

import

android.view.View;

public

class

ClockView

extends

View

{

private

Paint

circlePaint,

dialPaint,

numberPaint;

//

view

的宽高

private

float

mWidth,

mHeight;

//

圆的半径

private

float

circleRadius;

//

圆心X,Y坐标

private

float

circleX,

circleY;

private

int

second,

minute;

private

double

hour;

private

Handler

handler

=

new

Handler(Looper.getMainLooper())

{

@Override

public

void

handleMessage(Message

msg)

{

super.handleMessage(msg);

if

(msg.what

==

0)

{

invalidate();

}

}

};

public

ClockView(Context

context,

AttributeSet

attrs)

{

super(context,

attrs);

initPaint();

}

private

void

initPaint()

{

//

刻盘圆，小时刻度，时针和分针的画笔

circlePaint

=

new

Paint(Paint.ANTI_ALIAS_FLAG);

circlePaint.setColor(Color.BLACK);

circlePaint.setStyle(Paint.Style.STROKE);

circlePaint.setStrokeWidth(10);

//

分钟刻度的画笔

dialPaint

=

new

Paint(Paint.ANTI_ALIAS_FLAG);

dialPaint.setColor(Color.BLACK);

dialPaint.setStrokeWidth(5);

//

数字的画笔

numberPaint

=

new

Paint(Paint.ANTI_ALIAS_FLAG);

numberPaint.setColor(Color.BLACK);

numberPaint.setStrokeWidth(5);

numberPaint.setTextSize(30);

}

@Override

protected

void

onMeasure(int

widthMeasureSpec,

int

heightMeasureSpec)

{

super.onMeasure(widthMeasureSpec,

heightMeasureSpec);

mWidth

=

getMeasuredWidth();

mHeight

=

getMeasuredHeight();

if

(mWidth

<

mHeight)

{

//

圆的半径为view的宽度的一半再减9，防止贴边

circleRadius

=

mWidth

/

2

-

9;

circleX

=

mWidth

/

2;

circleY

=

mHeight

/

2;

}

else

{

circleRadius

=

mHeight

/

2

-

9;

circleX

=

mWidth

/

2;

circleY

=

mHeight

/

2;

}

}

@Override

protected

void

onDraw(Canvas

canvas)

{

super.onDraw(canvas);

setTimes();

drawCirclePoint(canvas);

drawCircle(canvas);

drawDial(canvas);

drawPointer(canvas);

}

/**

*

圆心

*

*

@param

canvas

*/

private

void

drawCirclePoint(Canvas

canvas)

{

canvas.drawCircle(circleX,

circleY,

5,

circlePaint);

}

private

void

drawCircle(Canvas

canvas)

{

canvas.drawCircle(circleX,

circleY,

circleRadius,

circlePaint);

}

/**

*

画刻度及时间

*

*

@param

canvas

*/

private

void

drawDial(Canvas

canvas)

{

//

时钟用长一点的刻度，画笔用画圆的画笔

Point

hourStartPoint

=

new

Point(circleX,

circleY

-

circleRadius);

Point

hourEndPoint

=

new

Point(circleX,

circleY

-

circleRadius

+

40);

//

分钟的刻度要稍微短一些，画笔用画圆的画笔

Point

startPoint2

=

new

Point(circleX,

circleY

-

circleRadius);

Point

endPoint2

=

new

Point(circleX,

circleY

-

circleRadius

+

10);

//

开始画刻度和数字，总共60个刻度，12个时钟刻度，被5整除画一个时钟刻度，被其余的为分针刻度

String

clockNumber;

for

(int

i

=

0;

i

<

60;

i++)

{

if

(i

%

5

==

0)

{

if

(i

==

0)

{

clockNumber

=

"12";

}

else

{

clockNumber

=

String.valueOf(i

/

5);

}

//

时针刻度

canvas.drawLine(hourStartPoint.getX(),

hourStartPoint.getY(),

hourEndPoint.getX(),

hourEndPoint.getY(),

circlePaint);

//

画数字，需在时针刻度末端加30

canvas.drawText(clockNumber,

circleX

-

numberPaint.measureText(clockNumber)

/

2,

hourEndPoint.getY()

+

30,

numberPaint);

}

else

{

//

画分针刻度

canvas.drawLine(startPoint2.getX(),

startPoint2.getY(),

endPoint2.getX(),

endPoint2.getY(),

circlePaint);

}

//

画布旋转6度

canvas.rotate(360

/

60,

circleX,

circleY);

}

}

/**

*

画指针

X点坐标

cos(弧度)*r

Y点坐标

sin(弧度)*r

toRadians将角度转成弧度

*

安卓坐标系与数学坐标系不同的地方是X轴是相反的，所以为了调整方向，需要将角度+270度

*

*

@param

canvas

*/

private

void

drawPointer(Canvas

canvas)

{

canvas.translate(circleX,

circleY);

float

hourX

=

(float)

Math.cos(Math.toRadians(hour

*

30

+

270))

*

circleRadius

*

0.5f;

float

hourY

=

(float)

Math.sin(Math.toRadians(hour

*

30

+

270))

*

circleRadius

*

0.5f;

float

minuteX

=

(float)

Math.cos(Math.toRadians(minute

*

6

+

270))

*

circleRadius

*

0.8f;

float

minuteY

=

(float)

Math.sin(Math.toRadians(minute

*

6

+

270))

*

circleRadius

*

0.8f;

float

secondX

=

(float)

Math.cos(Math.toRadians(second

*

6

+

270))

*

circleRadius

*

0.8f;

float

secondY

=

(float)

Math.sin(Math.toRadians(second

*

6

+

270))

*

circleRadius

*

0.8f;

canvas.drawLine(0,

0,

hourX,

hourY,

circlePaint);

canvas.drawLine(0,

0,

minuteX,

minuteY,

circlePaint);

canvas.drawLine(0,

0,

secondX,

secondY,

dialPaint);

//

一秒重绘一次

handler.sendEmptyMessageDelayed(0,

1000);

}

public

void

startClock()

{

setTimes();

invalidate();

}

private

void

setTimes()

{

Date

date

=

new

Date();

Calendar

calendar

=

Calendar.getInstance();

calendar.setTime(date);

second

=

getTimes(date,

Calendar.SECOND);

minute

=

getTimes(date,

Calendar.MINUTE);

hour

=

getTimes(date,

Calendar.HOUR)

+

minute

/

12

*

0.2;

}

private

int

getTimes(Date

date,

int

calendarField)

{

Calendar

calendar

=

Calendar.getInstance();

calendar.setTime(date);

return

calendar.get(calendarField);

}

public

void

stopClock()

{

handler.removeMessages(0);

}

}Point.java：package

com.example.clock;

public

class

Point

{

private

float

x;

private

float

y;

public

Point(float

x,

float

y)

{

this.x

=

x;

this.y

=

y;

}

public

float

getX()

{

return

x;

}

public

void

setX(float

x)

{

this.x

=

x;

}

public

float

getY()

{

return

y;

}

public

void

setY(float

y)

{

this.y

=

y;

}

}Acitivity（ClockActivity.java）：package

com.example.clock;

import

android.app.Activity;

import

android.os.Bundle;

public

class

ClockActivity

extends

Activity

{

/**

Called

when

the

activity

is

first

created.

*/

private

ClockView

clockView;

@Override

protected

void

onCreate(Bundle

savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

clockView

=

(ClockView)

findViewById(R.id.clock);

}

@Override

protected

void

onResume()

{

super.on