在values文件下有一个文件就是attrs.xml,这是R.attr和R.styleable类的定义文件。attrs.xml中定义了每个view的可用的属性，例如使用android:textAppearance就是在attrs.xml中定义了<attr name="textAppearance" format="reference" />，那麽这里点format="reference"使什么意思呢。
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 = "42dp"
android:layout_height = "42dp"
android:background = "@drawable/图片ID" />
2、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 = "42dp"
android:layout_height = "42dp"
android:textColor = "#ABABAB" />
3、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：
<TextView
android:layout_width = "42dp"
android:layout_height = "42dp"
android:focusable = "true" />
4、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：
<TextView
android:layout_width = "42dp"
android:layout_height = "42dp" />
5、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" />
6、integer：整形值
(1)属性定义：
<declare-styleable name="AnimatedRotateDrawable">
<attr name = "visible"/>
<attr name = "fromDuration " format="integer"/>
<attr name = "fromsCount " 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/anddroid"
android:drawable= "@drawable/图片ID"
android:pivotX = "50%"
android:pivotY = "50%"
android:framesCount = "12"
android:frameDuration= "100" />
7、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" />
8、fraction：百分数
(1)属性定义：
<decare-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" />
</decare-styleable>
(2)属性使用：
<rotate
xmlns:android = "[http://schemas.android.com/apk/res/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"/>
9、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>
10、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：
<declare-styleable name = "名称">
<attr name = "background" format = "reference|color" />
</declare-styleable>
(2)属性使用：
<ImageView
android:layout_width = "42dip"
android:layout_height = "42dip"
android:background = "@drawable/图片ID|#00FF00" />
