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)
<TextView test:属性名/>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"
/>