Android中attrs.xml文件的使用详解

2019-11-10 16:46:01

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1. attrs.xml 的作用

控件有很多属性，如 android:id、android:layout_width、android:layout_height等，但是这些属性都是系统自带的属性。使用attrs.xml文件，可以自己定义属性，下面我会写些小 demo ，比较好理解

2. 在values文件夹下，新建一个attrs.xml文件

内容如下：

<?xml version="1.0" encoding="utf-8"?><declare-styleable name="MyView"> <attr name="textColor" format="color" /> <attr name="textSize" format="dimension" /> </declare-styleable>

其中，

<declare-styleable name="MyView">

表明样式名称为MyView，下面包含了两个自定义属性textColor和textSize，其中textColor是颜色(color)类的属性，textSize是尺寸(dimension)类的属性

3. 自定义 MyView

public class MyView extends View { PRivate Paint mPaint; private static final String mString = "Welcome to BaiYe's blog"; public MyView(Context context) { this(context,null); } public MyView(Context context, AttributeSet attrs) { super(context, attrs); mPaint = new Paint(); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.MyView); int textColor = a.getColor(R.styleable.MyView_textColor, 0XFFFFFFFF); float textSize = a.getDimension(R.styleable.MyView_textSize, 36); mPaint.setTextSize(textSize); mPaint.setColor(textColor); a.recycle(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); // 设置填充 mPaint.setStyle(Paint.Style.FILL); // 画一个矩形,前俩个是矩形左上角坐标，后面俩个是右下角坐标// mPaint.setColor(Color.BLACK); canvas.drawRect(new Rect(10, 10, 100, 100), mPaint); // 绘制文字 canvas.drawText(mString, 60, 410, mPaint); }}首先从 R.styleable.CustomView 获得了TypedArray变量再用getColor()，getDimension()等方法获取相应的属性值，属性格式为“样式名_属性名”，属性后面的参数是默认值。获得属性值以后，就可以应用这些属性值。recycle()方法用于返回信号给资源（不懂什么意思）

4. xml 内容

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" xmlns:test="http://schemas.android.com/apk/res-auto"//一定记得添加前缀 android:id="@+id/activity_attrs_actiity" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.lizi.newset.CustomView.attrs.AttrsActivity"> <com.lizi.newset.CustomView.attrs.MyView android:id="@+id/myView" android:layout_height="match_parent" android:layout_width="wrap_content" test:textSize="50px" test:textColor="#ff00ff"/> /></RelativeLayout>

xmlns:test=”http://schemas.android.com/apk/res-auto”一定要添加，添加之后才能在xml中自定义属性

5. 自定义属性

格式如上，其中“xmlns:test”冒号后面是标签名，在下面使用时(只对当前文件可用)

5.1 reference：参考某一资源ID

<declare-styleable name = "名称"> <attr name = "background" format = "reference" /></declare-styleable>eg:<ImageView android:layout_width = "42dip" android:layout_height = "42dip" android:background = "@drawable/图片ID" />

5.2 color：颜色值

<declare-styleable name = "名称"> <attr name = "textColor" format = "color" /></declare-styleable>eg: <TextView android:layout_width = "42dip" android:layout_height = "42dip" android:textColor = "#00FF00" />

5.3 boolean：布尔值

<declare-styleable name = "名称"> <attr name = "focusable" format = "boolean" /></declare-styleable>eg:<Button android:layout_width = "42dip" android:layout_height = "42dip" android:focusable = "true"/>

5.4 dimension：尺寸值

<declare-styleable name = "名称"> <attr name = "layout_width" format = "dimension" /></declare-styleable>eg:<com.lizi.newset.CustomView.attrs.MyView android:id="@+id/myView" android:layout_height="match_parent" android:layout_width="wrap_content" test:textSize="50px" test:textColor="#ff00ff"/>

5.5 float：浮点值

<declare-styleable name = "AlphaAnimation"> <attr name = "fromAlpha" format = "float" /> <attr name = "toAlpha" format = "float" /></declare-styleable>eg:<alpha android:fromAlpha = "1.0" android:toAlpha = "0.7"/>

5.6 string：字符串

<declare-styleable name = "MapView"> <attr name = "apiKey" format = "string" /></declare-styleable>eg:<com.google.android.maps.MapView android:layout_width = "fill_parent" android:layout_height = "fill_parent" android:apiKey = "0jOkQ80oD1JL9C6HAja99uGXCRiS2CGjKO_bc_g" />

5.7 integer：整型值 || fraction：百分数

<declare-styleable name = "AnimatedRotateDrawable"> <attr name = "visible" /> <attr name = "frameDuration" format="integer" /> <attr name = "framesCount" format="integer" /> <attr name = "pivotX" format = "fraction"/> <attr name = "pivotY" format = "fraction"/> <attr name = "drawable" /></declare-styleable>eg:<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" />

5.8 enum：枚举值

<declare-styleable name="名称"> <attr name="orientation"> <enum name="horizontal" value="0" /> <enum name="vertical" value="1" /> </attr> </declare-styleable>eg:<LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android" android:orientation = "vertical" android:layout_width = "fill_parent" android:layout_height = "fill_parent" ></LinearLayout>

5.9 flag 位或运算

<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>eg:<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>

6. 属性定义时可以同时定义多种类型值

<declare-styleable name = "名称"> <attr name = "background" format = "reference|color" /></declare-styleable>eg:<ImageView android:layout_width = "42dip" android:layout_height = "42dip" android:background = "@drawable/图片ID|#00FF00" />

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