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.TypedArray obtainStyledAttributes(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();
}
@Override
protected 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 {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(new MyView(this));
setContentView(R.layout.my_view_main);
}
}
5、运行效果
