前段时间因为项目的需求,而需要自定义控件的AttributeSet属性,那么我们什么时候需要这种方法来自定义控件呢?好了,不卖关子啦,直接进入主题,一般是当项目中遇到这样的场景需要自定义控件的AttributeSet属性:一个自定义控件的有些属性内容是随着外部条件而动态改变的,for example:一个自定义的ListView控件,需要在底部添加一个View,而这个View在不同的模块使用中传入的View是不同的,这时候有两种方法,一种方法就是在自定义ListView控件类中提供一个公开的接口给外部调用从而将View动态的传入进去;另外一种方法就是在通过自定义控件属性,直接类似于系统属性如Android:textsize的用法 app:boottomView; 通过第二种方法自定义控件在XML中使用时和系统控件的属性使用方法一样,很简单、方便,而且动态、灵活、更具模块框架化,其属性内容直接在xml中动态配置,不了解其原理的人也能将该控件整合到自己的项目中快速使用起来。

自定义控件的AttributeSet属性步骤大致如下:

一、 首先要在res/values目录下建立一个attrs.xml(名字可以自己定义)的文件,并在此文件中增加对控件的属性的定义.其xml文件如下所示:

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <declare-styleable name="my_text_view">
       <attr name="text_size" format="float"></attr>
       <attr name="text_color" format="color"></attr>
       <attr name="text_back_ground" format="color|reference"></attr>

   </declare-styleable>
</resources>

在这里,需要补充attrs属性的相关知识,即Attr属性是如何在XML中定义的,自定义属性的Value值可以有10种类型以及其类型的组合值,其具体使用方法如下:

  1. reference:参考某一资源ID。
    (1)属性定义:
<declare-styleable name = "名称">

        <attr name = "background" format = "reference" />

            </declare-styleable>

(2)属性使用:

<ImageView

                     android:layout_width = "42dip"

                     android:layout_height = "42dip"

                     android:background = "@drawable/图片ID"

                     />
  1. color:颜色值。
    (1)属性定义:
<declare-styleable name = "名称">

           <attr name = "textColor" format = "color" />

    </declare-styleable>

(2)属性使用:

<TextView

             android:layout_width = "42dip"

             android:layout_height = "42dip"

             android:textColor = "#00FF00"

             />
  1. boolean:布尔值。

(1)属性定义:

<declare-styleable name = "名称">

        <attr name = "focusable" format = "boolean" />

    </declare-styleable>

(2)属性使用:

<Button

           android:layout_width = "42dip"

           android:layout_height = "42dip"

           android:focusable = "true"

            />
  1. dimension:尺寸值。
    (1)属性定义:
<declare-styleable name = "名称">

           <attr name = "layout_width" format = "dimension" />

    </declare-styleable>

(2)属性使用:

<Button

           android:layout_width = "42dip"

           android:layout_height = "42dip"

          />
  1. float:浮点值。

(1)属性定义:

<declare-styleable name = "AlphaAnimation">

           <attr name = "fromAlpha" format = "float" />

           <attr name = "toAlpha" format = "float" />

    </declare-styleable>

(2)属性使用:

<alpha

           android:fromAlpha = "1.0"

           android:toAlpha = "0.7"

           />
  1. integer:整型值。
    (1)属性定义:
<declare-styleable name = "AnimatedRotateDrawable">

           <attr name = "visible" />

           <attr name = "frameDuration" format="integer" />

           <attr name = "framesCount" format="integer" />

           <attr name = "pivotX" />

           <attr name = "pivotY" />

           <attr name = "drawable" />

    </declare-styleable>

(2)属性使用:

<animated-rotate

           xmlns:android = "http://schemas.android.com/apk/res/android"  

           android:drawable = "@drawable/图片ID"  

           android:pivotX = "50%"  

           android:pivotY = "50%"  

           android:framesCount = "12"  

           android:frameDuration = "100"

           />
  1. string:字符串。
    (1)属性定义:
<declare-styleable name = "MapView">

           <attr name = "apiKey" format = "string" />

    </declare-styleable>

(2)属性使用:

<com.google.android.maps.MapView

            android:layout_width = "fill_parent"

            android:layout_height = "fill_parent"

            android:apiKey = "0jOkQ80oD1JL9C6HAja99uGXCRiS2CGjKO_bc_g"

            />
  1. fraction:百分数。
    (1)属性定义:
<declare-styleable name="RotateDrawable">

           <attr name = "visible" />

           <attr name = "fromDegrees" format = "float" />

           <attr name = "toDegrees" format = "float" />

           <attr name = "pivotX" format = "fraction" />

           <attr name = "pivotY" format = "fraction" />

           <attr name = "drawable" />

    </declare-styleable>

(2)属性使用:

<rotate

         xmlns:android = "http://schemas.android.com/apk/res/android"

   android:interpolator = “@anim/动画ID”

android:fromDegrees = "0"

   android:toDegrees = “360”

android:pivotX = "200%"

         android:pivotY = "300%"

   android:duration = “5000”

android:repeatMode = "restart"

         android:repeatCount = "infinite"

        />
  1. enum:枚举值。
    (1)属性定义:
<declare-styleable name="名称">

           <attr name="orientation">

                  <enum name="horizontal" value="0" />

                  <enum name="vertical" value="1" />

           </attr>            

    </declare-styleable>

(2)属性使用:

<LinearLayout

            xmlns:android = "http://schemas.android.com/apk/res/android"

            android:orientation = "vertical"

            android:layout_width = "fill_parent"

            android:layout_height = "fill_parent"

            >

    </LinearLayout>
  1. flag:位或运算。
    (1)属性定义:
<declare-styleable name="名称">

            <attr name="windowSoftInputMode">

                    <flag name = "stateUnspecified" value = "0" />

                    <flag name = "stateUnchanged" value = "1" />

                    <flag name = "stateHidden" value = "2" />

                    <flag name = "stateAlwaysHidden" value = "3" />

                    <flag name = "stateVisible" value = "4" />

                    <flag name = "stateAlwaysVisible" value = "5" />

                    <flag name = "adjustUnspecified" value = "0x00" />

                    <flag name = "adjustResize" value = "0x10" />

                    <flag name = "adjustPan" value = "0x20" />

                    <flag name = "adjustNothing" value = "0x30" />

             </attr>         

     </declare-styleable>

(2)属性使用:

<activity

           android:name = ".StyleAndThemeActivity"

           android:label = "@string/app_name"

           android:windowSoftInputMode = "stateUnspecified | stateUnchanged | stateHidden">

           <intent-filter>

                  <action android:name = "android.intent.action.MAIN" />

                  <category android:name = "android.intent.category.LAUNCHER" />

           </intent-filter>

     </activity>

注意:

属性定义时可以指定多种类型值。

(1)属性定义:

<attr name = "background" format = "reference|color" />

    </declare-styleable>

(2)属性使

<ImageView

                     android:layout_width = "42dip"

                     android:layout_height = "42dip"

                     android:background = "@drawable/图片ID|#00FF00"

                     />

二、接下来实现自定义View的类,其中下面的构造方法是重点,在代码中获取自定义属性,其代码如下:

package com.example.CustomAttr;
import android.content.Context; 
 import android.content.res.TypedArray; 
 import android.graphics.Paint; 
 import android.util.AttributeSet; 
 import android.util.TypedValue; 
 import android.widget.TextView;/** 
 * Created with IntelliJ IDEA. 
 * User: zhiwen.nan 
 * Date: 13-9-28 
 * Time: 下午10:00 
 * To change this template use File | Settings | File Templates. 
 */ 
 public class CustomTextView extends TextView { 
 private TypedArray mTypedArray; 
 private Paint mPaint;
public CustomTextView(Context context) {
    super(context);
}

public CustomTextView(Context context, AttributeSet attrs) {
    super(context, attrs);
    inial(context,attrs);
}

public CustomTextView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    inial(context,attrs);
}

private void inial(Context context,AttributeSet attrs)  {
    TypedArray typedArray = context.obtainStyledAttributes(attrs,R.styleable.my_text_view);

    float textsize = typedArray.getFloat(R.styleable.my_text_view_text_size,14)   ;
    int textColor = typedArray.getColor(R.styleable.my_text_view_text_color,0xFFFFFF)   ;
    int bgColor = typedArray.getColor(R.styleable.my_text_view_text_back_ground,0xFFFFFF) ;

    super.setTextColor(textColor);
    super.setTextSize(textsize);
    super.setBackgroundColor(bgColor);


    typedArray.recycle();

}

}

三、接下来在XML布局中引用自定义View控件,其XML代码如下:

?xml version=”1.0” encoding=”utf-8”?>