首先,你需要在value文件夹下新建一个attr.xml文件(文件名可以任取,但不能有大写的字母开头).
内容大概有这些
<?xml version="1.0" encoding="utf-8"?> <resources> <declare-styleable name="CircleTip" > <attr name="circleTipColor" format="color" /> <attr name="circleTipRadiu" format="dimension" /> </declare-styleable> </resources>
稍稍解释下
<declare-styleable name="CircleTip" > 定义attr名称
<attr name="circleTipColor" format="color" /> 定义attr属性名称和对应的值的类型
接着使用这些attr属性,一般习惯做法是在构造函数里面对传入的attr做解析,因为这些属性值在xml布局文件里面定义了,我们需要取到作为View初始化的数据,接下来看怎么解析。
构造函数里面一般会传入一个AttributeSet对象(如果没有的话,那我们就取不到了),这个对象可以帮助我们取到xml定义的值。
TypedArray typedArray = context.obtainStyledAttributes(attrs,R.styleable.CircleTip);
这句可以帮助我们取到xml里面我们刚刚定义的declare-styleable的属性初始值。会把它存到TypedArray里,我们把里面的值取出来就好了。
mBGColor = typedArray.getColor(R.styleable.CircleTip_circleTipColor, defaultColor);
这样就取出来了。是不是很简单。
接着我们看看如何在xml布局文件里面使用新定义的attr属性。
首先你需要在使用的地方声明命名空间,那什么是命名空间呢?
xmlns:circle="http://schemas.android.com/apk/res/com.fineos.calendar"
诺,xmlns表示声明一个命名空间,命名空间的作用之一就是简化属性赋值,我们可以用xmlns后面跟着的单词表示“=”号后面比较长的空间名。命名空间声明完了以后就是设置属性值,用法就跟android:text一样啦,还是
给个例子。
circle:circleTipRadiu="7dp"
需要注意的是命名空间的写法
http://schemas.android.com/apk/res/ + 应用包名
先写到这里。
下面介绍下format的取值类型
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"/>
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" />
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" />
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" />
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"/>
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" />
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" />
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" />
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>
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" />