Android中自定義屬性（attrs.xml，TypedArray的使用）

做Android布局是件很享受的事，這得益于他良好的xml方式。使用xml可以快速有效的為軟體定義界面。可是有時候我們總感覺官方定義的一些基本元件不夠用，自定義元件就不可避免了。那麼如何才能做到像官方提供的那些元件一樣用xml來定義他的屬性呢？現在我們就來讨論一下他的用法。

1、添加檔案attrs.xml，位于res\values目錄下：

2、建立自定義控件：

3、在Activity布局檔案中使用自定義控件：

附：Android中自定義屬性的格式詳解

1. reference：參考某一資源ID。

    （1）屬性定義：

            <declare-styleable name = "名稱">

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

            </declare-styleable>

    （2）屬性使用：

             <ImageView

                     android:layout_width = "42dip"

                     android:layout_height = "42dip"

                     android:background = "@drawable/圖檔ID"

                     />

2. color：顔色值。

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

            <TextView

                     android:textColor = "#00FF00"

3. boolean：布爾值。

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

            <Button

                    android:layout_width = "42dip"

                    android:layout_height = "42dip"

                    android:focusable = "true"

                    />

4. dimension：尺寸值。

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

5. float：浮點值。

            <declare-styleable name = "AlphaAnimation">

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

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

            <alpha

                   android:fromAlpha = "1.0"

                   android:toAlpha = "0.7"

                   />

6. integer：整型值。

            <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" />

            <animated-rotate

                   android:drawable = "@drawable/圖檔ID" 

                   android:pivotX = "50%" 

                   android:pivotY = "50%" 

                   android:framesCount = "12" 

                   android:frameDuration = "100"

7. string：字元串。

            <declare-styleable name = "MapView">

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

            <com.google.android.maps.MapView

                    android:layout_width = "fill_parent"

                    android:layout_height = "fill_parent"

                    android:apiKey = "0jOkQ80oD1JL9C6HAja99uGXCRiS2CGjKO_bc_g"

8. fraction：百分數。

            <declare-styleable name="RotateDrawable">

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

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

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

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

　　             android:interpolator = "@anim/動畫ID"

                 android:fromDegrees = "0"

　　             android:toDegrees = "360"

                 android:pivotX = "200%"

                 android:pivotY = "300%"

　　             android:duration = "5000"

                 android:repeatMode = "restart"

                 android:repeatCount = "infinite"

9. enum：枚舉值。

            <declare-styleable name="名稱">

                   <attr name="orientation">

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

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

                   </attr>           

            <LinearLayout

                    android:orientation = "vertical"

                    >

            </LinearLayout>

10. flag：位或運算。

     （1）屬性定義：

             <declare-styleable name="名稱">

                    <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）屬性使用：

            <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：

     屬性定義時可以指定多種類型值。

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

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