在自定义View中使用自定义属性

自定义属性并使用

1在values目录下建立attrs.xml文件，在里面定义自己的属性，如下：

<?xml version="1.0" encoding="utf-8"?><resources>    <declare-styleable name="MyText">        <attr name="lineNum" format="integer"/>        <attr name="xScroll" format="boolean"/>        <attr name="mStr" format="string"/>    </declare-styleable></resources>

2在布局文件中使用自定义属性需要在根标签添加引用空间

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    xmlns:mtext="http://schemas.android.com/apk/res/com.duduhali.customview"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="com.duduhali.customview.MainActivity" >    <com.duduhali.customview.view.MyText        android:layout_width="match_parent"        android:layout_height="match_parent"        mtext:lineNum="3"        mtext:xScroll="true"        mtext:mStr="你好自定义View" /></RelativeLayout>

上面xmlns:mtext="http://schemas.android.com/apk/res/com.duduhali.customview"为添加引用空间。

mtext:lineNum="3"

mtext:xScroll="true"

mtext:mStr="你好自定义View" 

为使用自定义属性。

要时自定的属性起作用，要在自己的View中加以引用，上面的MyText的构造函数如下，在里面对自定义属性加以使用

public MyText(Context context, AttributeSet attrs) {super(context, attrs);// TODO Auto-generated constructor stubTypedArray ta = context.obtainStyledAttributes(attrs,R.styleable.MyText);lineNum = ta.getInt(R.styleable.MyText_lineNum, 1);xScroll = ta.getBoolean(R.styleable.MyText_xScroll, false);text = ta.getString(R.styleable.MyText_mStr);if( text == null){//设置未设置此属性时的默认值text = "一只哈巴狗";}ta.recycle();//回收TypedArray,此后就不能再使用此TypedArray}

其中的lineNum和xScroll为整形，text为字符串

自定义View的基类和子类如下：

BaseView.java

public abstract class BaseView extends View {private boolean running = true;private MyThread thread;protected abstract void drawSub(Canvas canvas);//子类通过此方法此方法把元素画到界面上protected abstract void logic();//在调用子类的drawSub()方法前调用，实现对绘画元素的处理public BaseView(Context context) {//代码中生成view时调用super(context);// TODO Auto-generated constructor stub}public BaseView(Context context, AttributeSet attrs) {//布局文件中定义view调用super(context, attrs);// TODO Auto-generated constructor stub}public BaseView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);// TODO Auto-generated constructor stub}@Overrideprotected final void onDraw(Canvas canvas) {// TODO Auto-generated method stubif(thread == null){thread = new MyThread();thread.start();}else{drawSub(canvas);}}/* * onDetachedFromWindow(),销毁view的时候调用，做收尾工作 * 相反，onAttachedToWindow()在第一次onDraw之前调用，只一次 */@Overrideprotected void onDetachedFromWindow() {// TODO Auto-generated method stubrunning = false;super.onDetachedFromWindow();}class MyThread extends Thread{@Overridepublic void run() {// TODO Auto-generated method stubwhile(running){logic();postInvalidate();try {Thread.sleep(30);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}}

MyText.java

public class MyText extends BaseView {private Paint paint = new Paint();private int lineNum = 0;private int mx = 0;private boolean xScroll = false;private String text;public MyText(Context context) {super(context);// TODO Auto-generated constructor stub}public MyText(Context context, AttributeSet attrs) {super(context, attrs);// TODO Auto-generated constructor stubTypedArray ta = context.obtainStyledAttributes(attrs,R.styleable.MyText);lineNum = ta.getInt(R.styleable.MyText_lineNum, 1);xScroll = ta.getBoolean(R.styleable.MyText_xScroll, false);text = ta.getString(R.styleable.MyText_mStr);if( text == null){//设置未设置此属性时的默认值text = "一只哈巴狗";}ta.recycle();//回收TypedArray,此后就不能再使用此TypedArray}@Overrideprotected void drawSub(Canvas canvas) {//此方法把元素画到界面上// TODO Auto-generated method stubfor(int i = 0; i < lineNum; i++ ){int textSize = 20 + i*10;paint.setTextSize(textSize);canvas.drawText(text, mx, textSize+textSize*i, paint);}}@Overrideprotected void logic() {//在调用drawSub()前被父类调用，实现对绘画元素的处理// TODO Auto-generated method stubif( xScroll ){mx += 2;if( mx > getWidth() ){mx = (int) - paint.measureText(text);/* * 获得字符串的现实宽度，必须是和context中资源相关联的,如： * TextView tv = new TextView(getContext()); * Paint p = tv.getPaint(); * float width = p.measureText(text); */}}}}

本demo是仿照极客学院上的案例做的
工程源码地址：http://download.csdn.net/detail/duduhali/9124585