Android中自定义属性（attrs.xml,TypedArray的使用）
16lz
2021-01-23
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
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