Android中自定义属性（attrs.xml,TypedArray的使用）

很多的时候，android的自带的控件不能满足我们的需求，需要进行自定义view,同时自定义属性，方便自定义view的个性化设计和代码管理，下面简单的介绍一下自定义属性：

一、TypedArray类

android.content.res.TypedArrayobtainStyledAttributes(AttributeSet, int[], int, int) obtainAttributes(AttributeSet, int[])

在执行完之后，一定要确保调用 recycle()函数，用于检索从这个结构对应于给定的属性位置到obtainStyledAttributes中的值

/**     * Give back a previously retrieved StyledAttributes, for later re-use.     */    public void recycle() {        synchronized (mResources.mTmpValue) {            TypedArray cached = mResources.mCachedStyledAttributes;            if (cached == null || cached.mData.length < mData.length) {                mXml = null;                mResources.mCachedStyledAttributes = this;            }        }    }

二、自定义attrs.xml与原生android属性的对比

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 = "your key"                    />

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：
          

   <span style="white-space:pre"></span>       <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>

     另外也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"                     />

三、实例演示

1、attrs.xml

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

2、my_view_main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:myview="http://schemas.android.com/apk/res/cn.jon.demo"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <cn.view.demo.MyView        android:layout_width="match_parent"        android:layout_height="match_parent"        myview:textColor="#00ff00"        myview:textSize="26sp">    </cn.view.demo.MyView></LinearLayout>

3、MyView.java

package cn.view.demo;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.util.AttributeSet;import android.view.View;import cn.jon.demo.R;public class MyView extends View {private Paint mPaint;public MyView(Context context) {this(context, null);}public MyView(Context context, AttributeSet attrs) {this(context, attrs, 0);}public MyView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);initViews(context, attrs);}private void initViews(Context context, AttributeSet attrs) {mPaint = new Paint();TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.MyView);int textColor = a.getColor(R.styleable.MyView_textColor, 0);float textSize = a.getDimension(R.styleable.MyView_textSize, 35);mPaint.setTextSize(textSize);mPaint.setColor(textColor);a.recycle();}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);mPaint.setAntiAlias(true);canvas.drawCircle(getWidth() / 2, getHeight() / 2, 80, mPaint);mPaint.setColor(Color.RED);canvas.drawText("circle", getWidth() / 2-40, getHeight() / 2, mPaint);mPaint.setColor(Color.BLUE);mPaint.setStrokeWidth(5);for (int y =30,alpha=255 ;alpha>2 ; alpha>>=1,y+=10) {mPaint.setAlpha(alpha);canvas.drawLine(getWidth() / 2-40,getHeight() / 2-y, 100, getHeight() / 2-y, mPaint);}}}

4、MyActivity.java

package cn.view.demo;import cn.jon.demo.R;import android.app.Activity;import android.os.Bundle;public class MyActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);//setContentView(new MyView(this));setContentView(R.layout.my_view_main);}}

5、运行效果