【移动应用开发技术】怎么在Android中通过自定义View绘制一个四位数随机码

【移动应用开发技术】怎么在Android中通过自定义View绘制一个四位数随机码

怎么在Android中通过自定义View绘制一个四位数随机码？相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。首先在res/values文件夹下建利attrs.xml文件，由于这次我们功能决定我们要提供三个自定义属性，分别是textTitleString类型的，textColor是color类型的，textSize是dimetion类型，代码如下：<?xml

version="1.0"

encoding="utf-8"?>

<resources>

<declare-styleable

name="MyTextView">

<attr

name="titleText"

format="string"/>

<attr

name="titleTextColor"

format="color"/>

<attr

name="titleTextSize"

format="dimension"/>

</declare-styleable>

</resources>再来看看我们怎么在布局文件中的自定义控件中去使用我们自定义的属性<?xml

version="1.0"

encoding="utf-8"?>

<RelativeLayout

xmlns:android="/apk/res/android"

xmlns:custom="/apk/res/com.qianmo.VerificationCode"

xmlns:tools="/tools"

android:layout_width="match_parent"

android:layout_height="match_parent">

<com.qianmo.VerificationCode.view.MyTextView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:padding="100dp"

custom:titleText="3712"

custom:titleTextColor="#ff0000"

android:layout_centerInParent="true"

custom:titleTextSize="40sp"/>

</RelativeLayout>关键的两句代码：xmlns:custom=”/apk/res/com.qianmo.VerificationCode”添加自定义的空间名，com.qianmo.VerificationCode使我们的包名，使用是以custom：开头，例如：custom:titleTextSize现在自定义的属性搞定了，开始我们的自定义View吧，首先选择，我们继承的是View还是ViewGroup，很明显，这次我们是一个简单的View，所以选择继承View，下面直接贴出来代码了，每一步代码里面都很详细，就不多给大家解释了package

com.qianmo.VerificationCode.view;

import

android.content.Context;

import

android.content.res.TypedArray;

import

android.graphics.Canvas;

import

android.graphics.Color;

import

android.graphics.Paint;

import

android.graphics.Rect;

import

android.util.AttributeSet;

import

android.util.Log;

import

android.util.TypedValue;

import

android.view.View;

import

com.qianmo.VerificationCode.R;

import

java.util.HashSet;

import

java.util.Random;

import

java.util.Set;

/**

*

Created

by

wangjitao

on

2016/10/13

0013.

*

用于实现获取随机码

*/

public

class

MyTextView

extends

View

{

/**

*

由于是自定义的View，首先我们要确定那些属性是用户可以自己定义的

*

1，View里面显示的字

*

2，显示字的大小

*

3，显示字的颜色

*/

private

String

mTitleText;

private

int

mTitleTextColor;

private

int

mTitleTextSize;

/**

*

画笔

*/

private

Paint

mPaint;

/**

*

view的矩形背景

*/

private

Rect

mBound;

public

MyTextView(Context

context)

{

this(context,

null);

}

public

MyTextView(Context

context,

AttributeSet

attrs)

{

this(context,

attrs,

0);

}

/**

*

获得自定义的属性

*

*

@param

context

*

@param

attrs

*

@param

defStyleAttr

*/

public

MyTextView(Context

context,

AttributeSet

attrs,

int

defStyleAttr)

{

super(context,

attrs,

defStyleAttr);

/**

*

获得我们自定义的一些属性

*/

TypedArray

a

=

context.getTheme().obtainStyledAttributes(attrs,

R.styleable.MyTextView,

defStyleAttr,

0);

mTitleText

=

randomText();

//初始化显示的数字

for

(int

i

=

0;

i

<

a.getIndexCount();

i++)

{

int

attr

=

a.getIndex(i);

switch

(attr)

{

case

R.styleable.MyTextView_titleText:

mTitleText

=

a.getString(attr);

break;

case

R.styleable.MyTextView_titleTextColor:

mTitleTextColor

=

a.getColor(attr,

Color.BLACK);

break;

case

R.styleable.MyTextView_titleTextSize:

//设置默认大小为16

mTitleTextSize

=

a.getDimensionPixelSize(attr,

(int)

TypedValue.applyDimension(

TypedValue.COMPLEX_UNIT_SP,

16,

getResources().getDisplayMetrics()));

break;

}

}

//将TypedArray对象回收

a.recycle();

/**

*

初始化画笔

*/

mPaint

=

new

Paint();

mPaint.setAntiAlias(true);

mPaint.setTextSize(mTitleTextSize);

mPaint.setColor(mTitleTextColor);

mBound

=

new

Rect();

mPaint.getTextBounds(mTitleText,

0,

mTitleText.length(),

mBound);

/**

*

模仿点击换验证码

*/

this.setOnClickListener(new

OnClickListener()

{

@Override

public

void

onClick(View

view)

{

mTitleText

=

randomText();

postInvalidate();

}

});

}

/**

*

获取四位随机数验证码

*

*

@return

*/

private

String

randomText()

{

Random

random

=

new

Random();

Set<Integer>

set

=

new

HashSet<Integer>();

while

(set.size()

<

4)

{

int

randomInt

=

random.nextInt(10);

set.add(randomInt);

}

StringBuffer

sb

=

new

StringBuffer();

for

(Integer

i

:

set)

{

sb.append(""

+

i);

}

return

sb.toString();

}

@Override

protected

void

onMeasure(int

widthMeasureSpec,

int

heightMeasureSpec)

{

/**

*

处理当宽高都是wrap_content的情况

*/

int

widthMode

=

MeasureSpec.getMode(widthMeasureSpec);

int

widthSize

=

MeasureSpec.getSize(widthMeasureSpec);

int

heightMode

=

MeasureSpec.getMode(heightMeasureSpec);

int

heightSize

=

MeasureSpec.getSize(heightMeasureSpec);

int

width

=

0;

int

height

=

0;

if

(widthMode

==

MeasureSpec.EXACTLY)

{

width

=

widthSize;

}

else

{

mPaint.setTextSize(mTitleTextSize);

mPaint.getTextBounds(mTitleText,

0,

mTitleText.length(),

mBound);

float

textWidth

=

mBound.width();

int

desired

=

(int)

(getPaddingLeft()

+

textWidth

+

getPaddingRight());

width

=

desired;

}

if

(heightMode

==

MeasureSpec.EXACTLY)

{

height

=

heightSize;

}

else

{

mPaint.setTextSize(mTitleTextSize);

mPaint.getTextBounds(mTitleText,

0,

mTitleText.length(),

mBound);

float

textWidth

=

mBound.height();

int

desired

=

(int)

(getPaddingTop()

+

textWidth

+

getPaddingBottom());

height

=

desired;

}

setMeasuredDimension(width,

height);

}

@Override

protected

void

onDraw(Canvas

canvas)

{

/**

*

绘