打造一个动态切换文本的TextView

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效果图

此处输入图片的描述

思路

继承自TextView,在指定时间调用setText()方法切换文本,并且设置进入退出动画

代码解析

代码不多，简洁明了

public class FadingTextView extends TextView {    private Animation fadeInAnimation, fadeOutAnimation;//切换文本动画    private int duration;//切换时间,默认3秒    private final int DEFAULT_DURATION = 3000;    private CharSequence[] textContents;//文本内容    private int textPosition = 0;//当前显示的文本角标    private boolean isShown;//是否可见    public FadingTextView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        fadeInAnimation = AnimationUtils.loadAnimation(context, R.anim.fade_in);        fadeOutAnimation = AnimationUtils.loadAnimation(context, R.anim.fade_out);        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.FadingTextView);        duration = a.getInteger(R.styleable.FadingTextView_duration, DEFAULT_DURATION);        textContents = a.getTextArray(R.styleable.FadingTextView_texts);        a.recycle();    }    public FadingTextView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public FadingTextView(Context context) {        this(context, null);    }    @Override    protected void onAttachedToWindow() {        super.onAttachedToWindow();        isShown = true;        start();    }    @Override    protected void onDetachedFromWindow() {//涉及动画，需要在detach方法停止不然会造成内存泄漏        super.onDetachedFromWindow();        stop();    }    /**     * 设置文本内容     *     * @param texts     */    public void setTexts(String... texts) {        if (texts.length < 1) {            throw new IllegalArgumentException("This TextView's contents' length must more than 1");        }        textContents = texts;    }    /**     * 设置文本内容     *     * @param resourceId     */    public void setTexts(@ArrayRes int resourceId) {        String[] texts = getContext().getResources().getStringArray(resourceId);        if (texts != null) {            if (texts.length < 1) {                throw new IllegalArgumentException("This TextView's contents' length must more than 1");            }            textContents = texts;        }    }    /**     * 设置持续时间     *     * @param duration     */    public void setDuration(int duration) {        if (duration < 1) {            throw new IllegalArgumentException("duration must more than 1");        }        this.duration = duration;    }    /**     * 获取设置的文本内容     *     * @return     */    public CharSequence[] getTextContents() {        return textContents;    }    /**     * 开始     */    private void start() {        setText(textContents[textPosition]);        startAnimation(fadeInAnimation);        postDelayed(animRunnable, duration);    }    /**     * 停止     */    private void stop() {        if (getAnimation() != null) {            getAnimation().cancel();        }        isShown = false;        removeCallbacks(animRunnable);    }    private final Runnable animRunnable = new Runnable() {        @Override        public void run() {            startAnimation(fadeOutAnimation);            getAnimation().setAnimationListener(new Animation.AnimationListener() {                @Override                public void onAnimationStart(Animation animation) {                }                @Override                public void onAnimationEnd(Animation animation) {                    if (isShown) {                        textPosition = (textPosition == (textContents.length - 1)) ? 0 : (textPosition + 1);                        start();                    }                }                @Override                public void onAnimationRepeat(Animation animation) {                }            });        }    };}

准备工作：

自定义属性的声明，获取，动画的初始化工作

自定义属性声明

  <declare-styleable name="FadingTextView">        <attr name="duration" format="integer" />        <attr name="texts" format="reference" />    </declare-styleable>

自定义属性的获取

 TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.FadingTextView);        duration = a.getInteger(R.styleable.FadingTextView_duration, DEFAULT_DURATION);        textContents = a.getTextArray(R.styleable.FadingTextView_texts);        a.recycle();

动画的声明跟获取

fade_in<?xml version="1.0" encoding="utf-8"?><set xmlns:android="http://schemas.android.com/apk/res/android">    <alpha        android:duration="@android:integer/config_longAnimTime"        android:fromAlpha="0.0"        android:toAlpha="1.0"        android:interpolator="@android:anim/linear_interpolator"        /></set>fade_out<?xml version="1.0" encoding="utf-8"?><set xmlns:android="http://schemas.android.com/apk/res/android">    <alpha        android:duration="@android:integer/config_longAnimTime"        android:fromAlpha="1.0"        android:toAlpha="0.0"        android:interpolator="@android:anim/linear_interpolator"        /></set>

获取动画

  fadeInAnimation = AnimationUtils.loadAnimation(context, R.anim.fade_in);  fadeOutAnimation = AnimationUtils.loadAnimation(context, R.anim.fade_out);

第一步：

既然是动态切换文本，那需要的text文本肯定是需要多个，不然无法达到切换的目的

 /**     * 设置文本内容     *     * @param texts     */    public void setTexts(String... texts) {        if (texts.length < 1) {            throw new IllegalArgumentException("This TextView's contents' length must more than 1");        }        textContents = texts;    }    /**     * 设置文本内容     *     * @param resourceId     */    public void setTexts(@ArrayRes int resourceId) {        String[] texts = getContext().getResources().getStringArray(resourceId);        if (texts.length < 1) {            throw new IllegalArgumentException("This TextView's contents' length must more than 1");        }        textContents = texts;    }

第二步：

给TextView设置文本、动画，达到渐变效果

    /**     * 开始     */    private void start() {        setText(textContents[textPosition]);        startAnimation(fadeInAnimation);        postDelayed(animRunnable, duration);    }

第三步：

定时更新文本内容

 private final Runnable animRunnable = new Runnable() {        @Override        public void run() {            startAnimation(fadeOutAnimation);            getAnimation().setAnimationListener(new Animation.AnimationListener() {                @Override                public void onAnimationStart(Animation animation) {                }                @Override                public void onAnimationEnd(Animation animation) {                    if (isShown) {                        textPosition = (textPosition == (textContents.length - 1)) ? 0 : (textPosition + 1);                        start();                    }                }                @Override                public void onAnimationRepeat(Animation animation) {                }            });        }    };

第四步：

资源的回收

 @Override    protected void onDetachedFromWindow() {//涉及动画，需要在detach方法停止不然会造成内存泄漏        super.onDetachedFromWindow();        stop();    }     /**     * 停止     */    private void stop() {        if (getAnimation() != null) {            getAnimation().cancel();        }        isShown = false;        removeCallbacks(animRunnable);    }

第五步：

使用

  <com.qfxl.android.fadingTextView.FadingTextView        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:gravity="center"        android:textColor="@android:color/white"        android:textSize="30sp"        qfxl:duration="2000"        qfxl:texts="@array/arrayTest" />

总结

这个是闲暇时间逛github的时候看到的，觉得挺实用简单，就写了一下。
没事多逛逛github，会发现很多惊喜

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