做Android布局是件很享受的事,这得益于他良好的xml方式。使用xml可以快速有效的为软件定义界面。可是有时候我们总感觉官方定义的一些基本组件不够用,自定义组件就不可避免了。那么如何才能做到像官方提供的那些组件一样用xml来定义他的属性呢?现在我们就来讨论一下他的用法。
1、添加文件attrs.xml,位于res\values目录下:
<?xml version="1.0" encoding="utf-8"?> <resources> <declare-styleable name="myView"> <attr name="textColor" format="color"/> <attr name="textSize" format="dimension"/> </declare-styleable> </resources>
2、创建自定义控件:
public class MyView extends View { private Paint myPaint; private static final String myString = "Hello CustomView!"; public MyView(Context context) { super(context); // TODO Auto-generated constructor stub } public MyView(Context context, AttributeSet attr) { super(context, attr); myPaint = new Paint(); TypedArray a = context.obtainStyledAttributes(attr, R.styleable.myView);//TypedArray是一个数组容器 float textSize = a.getDimension(R.styleable.myView_textSize, 30);//防止在XML文件里没有定义,就加上了默认值30 int textColor = a.getColor(R.styleable.myView_textColor, 0xFFFFFFFF);//同上,这里的属性是:名字_属性名 myPaint.setTextSize(textSize); myPaint.setColor(textColor); a.recycle();//我的理解是:返回以前取回的属性,供以后使用。以前取回的可能就是textSize和textColor初始化的那段 } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); myPaint.setColor(Color.RED); myPaint.setStyle(Style.FILL); canvas.drawRect(new Rect(10,10,100,100), myPaint); myPaint.setColor(Color.WHITE); canvas.drawText(myString, 10, 100, myPaint); } }
3、在Activity布局文件中使用自定义控件:
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="<a href="http://schemas.android.com/apk/res/android">http://schemas.android.com/apk/res/android</a>" xmlns:test="<a href="http://schemas.android.com/apk/res/com.szy.custom">http://schemas.android.com/apk/res/com.szy.custom</a>" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello" /> <com.adnroid.test.MyView android:layout_width="fill_parent" android:layout_height="fill_parent" test:textSize="10px" test:textColor="#fff" /> </LinearLayout>
附:Android中自定义属性的格式详解
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 =
"42dip"
android:layout_height =
"42dip"
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 =
"42dip"
android:layout_height =
"42dip"
android:textColor =
"#00FF00"
/>
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:
<Button
android:layout_width =
"42dip"
android:layout_height =
"42dip"
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:
<Button
android:layout_width =
"42dip"
android:layout_height =
"42dip"
/>
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"
/>
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:
<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"
/>
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"
/>