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：
package com.szy.custom; import com.szy.custom.R; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; import android.graphics.Paint.Style; import android.util.AttributeSet; import android.view.View; 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) { // TODO Auto-generated method stub super.onDraw(canvas); //myPaint = new Paint(); 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：<ImageViewandroid: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：<TextViewandroid: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：<Buttonandroid: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：<Buttonandroid: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：<alphaandroid: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-rotatexmlns: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.MapViewandroid: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：<LinearLayoutxmlns: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：<activityandroid: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：<ImageViewandroid:layout_width = "42dip"android:layout_height = "42dip"android:background = "@drawable/图片ID|#00FF00"/>
