android开发游记:自定义实现图片轮播器和启动页面滚动

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图片轮播器是一种交互很好的广告推送的组件,既完成了我们向用户推送信息的目的,同时形式还很优雅,在app中都有使用到,但是android的源生组件中并没有轮播器,这样我们就需要自定义来实现一个了。

先上效果图,分为自动滚动和手动滚动:

这里写图片描述 这里写图片描述

首先新建一个布局文件,添加以下代码:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <android.support.v4.view.ViewPager        android:id="@+id/viewPager"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:background="@color/white" />    <LinearLayout        android:id="@+id/dotLayout"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_marginBottom="20dp"        android:gravity="center"        android:orientation="horizontal"        android:padding="8dp" >        <View            android:id="@+id/v_dot1"            android:layout_width="8dp"            android:layout_height="8dp"            android:background="@drawable/shape_oval_dot_orage" />        <View            android:id="@+id/v_dot2"            android:layout_width="8dp"            android:layout_height="8dp"            android:layout_marginLeft="25dp"            android:background="@drawable/shape_oval_dot_dark" />    </LinearLayout></RelativeLayout>

轮播器内部其实也是使用了viewPager,首先自定义一个PagerAdapter来初始化每页的View,其实每页只有一个ImageView:

     /**     * 填充ViewPager的页面适配器     *      */    private class MyPagerAdapter  extends PagerAdapter{        @Override        public void destroyItem(View container, int position, Object object) {            // TODO Auto-generated method stub            //((ViewPag.er)container).removeView((View)object);            ((ViewPager)container).removeView(imageViewsList.get(position));        }        @Override        public Object instantiateItem(ViewGroup container, int position) {            ImageView imageView = imageViewsList.get(position);            if (!StringUtil.isEmpty(imageUrls)) {                if (imageUrls[0].contains("http")) {                    bitmapUtils.display(imageView, imageView.getTag().toString());                }else {                    imageView.setImageResource(Integer.parseInt(imageUrls[position]));                }            }            imageView.setBackgroundResource(R.color.white);            container.addView(imageView);            return imageView;        }        @Override        public int getCount() {            // TODO Auto-generated method stub            return imageViewsList.size();        }}

在instantiateItem中初始化这个ImageView并返回,这里我做了一些业务处理上的处理,我定义了2中传入图片的方式,如果请求到了一组图片就存放url,如果失败了那么现实默认的本地图片(以Resource方式存放),图片的集合存放的是URL还是Resource。不需要这样处理可以把这里的代码删掉就可以了。

然后给ViewPager设置一个监听器,监听到翻页事件:

private class MyPageChangeListener implements OnPageChangeListener{        boolean isAutoPlay = false;        @Override        public void onPageScrollStateChanged(int arg0) {            // TODO Auto-generated method stub            switch (arg0) {            case 1:// 手势滑动,空闲中                isAutoPlay = false;                break;            case 2:// 界面切换中                isAutoPlay = true;                break;            case 0:// 滑动结束,即切换完毕或者加载完毕                if (isAutoPlay) {                    // 当前为最后一张,此时从右向左滑,则切换到第一张                    if (viewPager.getCurrentItem() == viewPager.getAdapter().getCount() - 1 && !isAutoPlay) {                        viewPager.setCurrentItem(0);                    }                    // 当前为第一张,此时从左向右滑,则切换到最后一张                    else if (viewPager.getCurrentItem() == 0 && !isAutoPlay) {                        viewPager.setCurrentItem(viewPager.getAdapter().getCount() - 1);                    }                }                break;            }        }        @Override        public void onPageScrolled(int arg0, float arg1, int arg2) {            // TODO Auto-generated method stub        }        @Override        public void onPageSelected(int pos) {            // TODO Auto-generated method stub            currentItem = pos;            for(int i=0;i < dotViewsList.size();i++){                if(i == pos){                    ((View)dotViewsList.get(pos)).setBackgroundResource(R.drawable.shape_oval_dot_orage);                }else {                    ((View)dotViewsList.get(i)).setBackgroundResource(R.drawable.shape_oval_dot_dark);                }            }        }    }

在onPageScrollStateChanged方法中处理最后一张图片和第一张图片的特殊情况:

  1. 如果在第一张图片的位置往前翻页则跳到最后一页。
  2. 如果在最后一张图片往后翻页则跳到第一页

在onPageSelected方法中处理悬浮的小点点的热点效果,把当前页对应的小点点设置为热点显示高亮状态

定义一个initUI方法,在请求到图片之后调用以初始化控件:

     /**     * 初始化Views等UI     */    private void initUI(Context context){        if(imageUrls == null || imageUrls.length == 0)            return;        LayoutInflater.from(context).inflate(R.layout.layout_slideshow, this, true);        LinearLayout dotLayout = (LinearLayout)findViewById(R.id.dotLayout);        dotLayout.removeAllViews();        // 热点个数与图片特殊相等        for (int i = 0; i < imageUrls.length; i++) {            ImageView view =  new ImageView(context);            view.setTag(imageUrls[i]);            view.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));            imageViewsList.add(view);            ImageView dotView =  new ImageView(context);            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);            params.leftMargin = 15;            params.rightMargin = 15;            dotLayout.addView(dotView, params);            dotViewsList.add(dotView);        }        /////////首次进入的时候初始化点点        for(int i=0;i < dotViewsList.size();i++){            if(i == 0){                ((View)dotViewsList.get(0)).setBackgroundResource(R.drawable.shape_oval_dot_orage);            }else {                ((View)dotViewsList.get(i)).setBackgroundResource(R.drawable.shape_oval_dot_dark);            }        }        //////////////////////////        if (imageViewsList.size()>0 && goListener!=null) {            imageViewsList.get(imageViewsList.size()-1).setOnClickListener(goListener);        }        viewPager = (ViewPager) findViewById(R.id.viewPager);        viewPager.setFocusable(true);        viewPager.setAdapter(new MyPagerAdapter());        viewPager.setOnPageChangeListener(new MyPageChangeListener());    }

initUI方法中初始化了Viewpager也设置了Adapter,那么只要在获取到图片数据之后调用该方法就OK了
定义一个后台异步任务,用于从服务器获取图片集合,获取完成后调用initUI()方法:

    /**     * 异步任务,获取数据     *      */    class GetListTask extends AsyncTask<String, Integer, Boolean> {        @Override        protected Boolean doInBackground(String... params) {            try {                // 这里一般调用服务端接口获取一组轮播图片,下面是从百度找的几个图片                     imageUrls = new String[]{                        "http://image.zcool.com.cn/59/54/m_1303967870670.jpg",                        "http://image.zcool.com.cn/47/19/1280115949992.jpg",                        "http://image.zcool.com.cn/59/11/m_1303967844788.jpg"                };                return true;            } catch (Exception e) {                e.printStackTrace();                return false;            }        }        @Override        protected void onPostExecute(Boolean result) {            super.onPostExecute(result);            if (result) {                initUI(context);            }        }    }

这里就模拟了,写一组静态图片,需要请求服务器图片的在这里请求

然后再添加自动播放的功能,在初始化的时候创建一个异步任务,每隔一段时间,进行一次发生一个handler消息,handler接收到消息后进行翻页:

     /**     * 开始轮播图切换     */    private void startPlay(){        scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();        scheduledExecutorService.scheduleAtFixedRate(new SlideShowTask(), 4, 4, TimeUnit.SECONDS);    }     /**     *执行轮播图切换任务     *     */    private class SlideShowTask implements Runnable{        @Override        public void run() {            // TODO Auto-generated method stub            synchronized (viewPager) {                currentItem = (currentItem+1)%imageViewsList.size();                handler.obtainMessage().sendToTarget();            }        }       }     //Handler    private Handler handler = new Handler(){        @Override        public void handleMessage(Message msg) {            super.handleMessage(msg);            viewPager.setCurrentItem(currentItem);        }    };

然后设置一个标志位来决定是否需要自动轮播或者手动翻页,
需要手动翻页就调用startPlay(),不需要就跳过:

if(isAutoPlay){     startPlay();}

这样功能基本就完了,下面贴上完整代码:

/** * ViewPager实现的轮播图广告自定义视图,如京东首页的广告轮播图效果; * 既支持自动轮播页面也支持手势滑动切换页面 *  * */public class SlideShowView extends FrameLayout {    // 使用universal-image-loader插件读取网络图片,需要工程导入universal-image-loader-1.8.6-with-sources.jar//  private ImageLoader imageLoader = ImageLoader.getInstance();    private BitmapUtils bitmapUtils;    //轮播图图片数量    private final static int IMAGE_COUNT = 4;    //自动轮播的时间间隔    private final static int TIME_INTERVAL = 5;    //自动轮播启用开关    private final static boolean isAutoPlay = false;     //跳转监听器    private OnClickListener goListener;    //自定义轮播图的资源    private String[] imageUrls;//    private int[] imageSrcs;    //放轮播图片的ImageView 的list    private List<ImageView> imageViewsList;    //放圆点的View的list    private List<View> dotViewsList;    private ViewPager viewPager;    //当前轮播页    private int currentItem  = 0;    //定时任务    private ScheduledExecutorService scheduledExecutorService;    private Context context;    //Handler    private Handler handler = new Handler(){        @Override        public void handleMessage(Message msg) {            super.handleMessage(msg);            viewPager.setCurrentItem(currentItem);        }    };    public SlideShowView(Context context) {        this(context,null);    }    public SlideShowView(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public SlideShowView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        if (!isInEditMode()) {            this.context = context;            this.bitmapUtils = BitmapHelp.getBitmapUtils();            this.bitmapUtils.configDefaultLoadingImage(R.drawable.none);            this.bitmapUtils.configDefaultLoadFailedImage(R.drawable.none);            initData();            // 一步任务获取图片            new GetListTask().execute("");            if(isAutoPlay){                startPlay();            }        }    }    /**     * 开始轮播图切换     */    private void startPlay(){        scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();        scheduledExecutorService.scheduleAtFixedRate(new SlideShowTask(), 4, 4, TimeUnit.SECONDS);    }    /**     * 停止轮播图切换     */    private void stopPlay(){        scheduledExecutorService.shutdown();    }    /**     * 初始化相关Data     */    private void initData(){        imageViewsList = new ArrayList<ImageView>();        dotViewsList = new ArrayList<View>();    }    /**     * 初始化Views等UI     */    private void initUI(Context context){        if(imageUrls == null || imageUrls.length == 0)            return;        LayoutInflater.from(context).inflate(R.layout.layout_slideshow, this, true);        LinearLayout dotLayout = (LinearLayout)findViewById(R.id.dotLayout);        dotLayout.removeAllViews();        // 热点个数与图片特殊相等        for (int i = 0; i < imageUrls.length; i++) {            ImageView view =  new ImageView(context);            view.setTag(imageUrls[i]);//          if(i==0)//给一个默认图//              view.setBackgroundResource(R.drawable.defalt);            view.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));//          view.setScaleType(ScaleType.FIT_START);            imageViewsList.add(view);            ImageView dotView =  new ImageView(context);            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);            params.leftMargin = 15;            params.rightMargin = 15;            dotLayout.addView(dotView, params);            dotViewsList.add(dotView);        }        /////////首次进入的时候初始化点点        for(int i=0;i < dotViewsList.size();i++){            if(i == 0){                ((View)dotViewsList.get(0)).setBackgroundResource(R.drawable.shape_oval_dot_orage);            }else {                ((View)dotViewsList.get(i)).setBackgroundResource(R.drawable.shape_oval_dot_dark);            }        }        //////////////////////////        if (imageViewsList.size()>0 && goListener!=null) {            imageViewsList.get(imageViewsList.size()-1).setOnClickListener(goListener);        }        viewPager = (ViewPager) findViewById(R.id.viewPager);        viewPager.setFocusable(true);        viewPager.setAdapter(new MyPagerAdapter());        viewPager.setOnPageChangeListener(new MyPageChangeListener());    }    public void setOnGolistener(OnClickListener goListener) {        this.goListener = goListener;    }    /**     * 填充ViewPager的页面适配器     *      */    private class MyPagerAdapter  extends PagerAdapter{        @Override        public void destroyItem(View container, int position, Object object) {            // TODO Auto-generated method stub            //((ViewPag.er)container).removeView((View)object);            ((ViewPager)container).removeView(imageViewsList.get(position));        }        @Override        public Object instantiateItem(ViewGroup container, int position) {            ImageView imageView = imageViewsList.get(position);            if (!StringUtil.isEmpty(imageUrls)) {                if (imageUrls[0].contains("http")) {                    bitmapUtils.display(imageView, imageView.getTag().toString());                }else {                    imageView.setImageResource(Integer.parseInt(imageUrls[position]));                }            }            imageView.setBackgroundResource(R.color.white);            container.addView(imageView);            return imageView;        }        @Override        public int getCount() {            // TODO Auto-generated method stub            return imageViewsList.size();        }        @Override        public boolean isViewFromObject(View arg0, Object arg1) {            // TODO Auto-generated method stub            return arg0 == arg1;        }        @Override        public void restoreState(Parcelable arg0, ClassLoader arg1) {            // TODO Auto-generated method stub        }        @Override        public Parcelable saveState() {            // TODO Auto-generated method stub            return null;        }        @Override        public void startUpdate(View arg0) {            // TODO Auto-generated method stub        }        @Override        public void finishUpdate(View arg0) {            // TODO Auto-generated method stub        }    }    /**     * ViewPager的监听器     * 当ViewPager中页面的状态发生改变时调用     *      */    private class MyPageChangeListener implements OnPageChangeListener{        boolean isAutoPlay = false;        @Override        public void onPageScrollStateChanged(int arg0) {            // TODO Auto-generated method stub            switch (arg0) {            case 1:// 手势滑动,空闲中                isAutoPlay = false;                break;            case 2:// 界面切换中                isAutoPlay = true;                break;            case 0:// 滑动结束,即切换完毕或者加载完毕                if (isAutoPlay) {                    // 当前为最后一张,此时从右向左滑,则切换到第一张                    if (viewPager.getCurrentItem() == viewPager.getAdapter().getCount() - 1 && !isAutoPlay) {                        viewPager.setCurrentItem(0);                    }                    // 当前为第一张,此时从左向右滑,则切换到最后一张                    else if (viewPager.getCurrentItem() == 0 && !isAutoPlay) {                        viewPager.setCurrentItem(viewPager.getAdapter().getCount() - 1);                    }                }                break;            }        }        @Override        public void onPageScrolled(int arg0, float arg1, int arg2) {            // TODO Auto-generated method stub        }        @Override        public void onPageSelected(int pos) {            // TODO Auto-generated method stub            currentItem = pos;            for(int i=0;i < dotViewsList.size();i++){                if(i == pos){                    ((View)dotViewsList.get(pos)).setBackgroundResource(R.drawable.shape_oval_dot_orage);                }else {                    ((View)dotViewsList.get(i)).setBackgroundResource(R.drawable.shape_oval_dot_dark);                }            }        }    }    /**     *执行轮播图切换任务     *     */    private class SlideShowTask implements Runnable{        @Override        public void run() {            // TODO Auto-generated method stub            synchronized (viewPager) {                currentItem = (currentItem+1)%imageViewsList.size();                handler.obtainMessage().sendToTarget();            }        }    }    /**     * 销毁ImageView资源,回收内存     *      */    private void destoryBitmaps() {        for (int i = 0; i < IMAGE_COUNT; i++) {            ImageView imageView = imageViewsList.get(i);            Drawable drawable = imageView.getDrawable();            if (drawable != null) {                //解除drawable对view的引用                drawable.setCallback(null);            }        }    }    /**     * 释放资源,在activity结束时请调用     */    public void destory() {        stopPlay();        destoryBitmaps();    }    public void setImageSrcs(int[] imageSrcs) {        if (StringUtil.isEmpty(imageSrcs)) {            return;        }        imageUrls = new String[imageSrcs.length];        for (int i = 0; i < imageSrcs.length; i++) {            imageUrls[i] = imageSrcs[i]+"";        }    }    public void setImageUrls(String[] imageUrls) {        this.imageUrls = imageUrls;    }    /**     * 异步任务,获取数据     *      */    class GetListTask extends AsyncTask<String, Integer, Boolean> {        @Override        protected Boolean doInBackground(String... params) {            try {                // 这里一般调用服务端接口获取一组轮播图片,下面是从百度找的几个图片                imageUrls = new String[]{                        "http://image.zcool.com.cn/59/54/m_1303967870670.jpg",                        "http://image.zcool.com.cn/47/19/1280115949992.jpg",                        "http://image.zcool.com.cn/59/11/m_1303967844788.jpg"                };                return true;            } catch (Exception e) {                e.printStackTrace();                return false;            }        }        @Override        protected void onPostExecute(Boolean result) {            super.onPostExecute(result);            if (result) {                initUI(context);            }        }    }}
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