ViewPager实现图片轮翻效果

很多App都有这种效果，特别一些电商类的App，顶部每隔几秒钟会向右翻页显示下张图片，用来作推广或者内容展示用的。今天来简单地模仿一下，还自带一个自动跳动的小功能（底部有几个小点，图片移动的时候，点的状态也在变化），用定时器来实现不难。

    import java.util.ArrayList;  

    import java.util.concurrent.Executors;  

    import java.util.concurrent.ScheduledExecutorService;  

    import java.util.concurrent.TimeUnit;  

      

    import android.app.Activity;  

    import android.os.Bundle;  

    import android.os.Handler;  

    import android.os.Message;  

    import android.support.v4.view.PagerAdapter;  

    import android.support.v4.view.ViewPager;  

    import android.support.v4.view.ViewPager.OnPageChangeListener;  

    import android.view.View;  

    import android.view.ViewGroup;  

    import android.widget.ImageView;  

    import android.widget.TextView;  

      

    public class MainActivity extends Activity {  

        private int imageIds[];  

        private String[] titles;  

        private ArrayList<ImageView> images;  

        private ArrayList<View> dots;  

        private TextView title;  

        private ViewPager mViewPager;  

        private ViewPagerAdapter adapter;  

        private int oldPosition = 0;//记录上一次点的位置  

        private int currentItem; //当前页面  

        private ScheduledExecutorService scheduledExecutorService;  

        @Override  

        public void onCreate(Bundle savedInstanceState) {  

            super.onCreate(savedInstanceState);  

            setContentView(R.layout.activity_main);  

            //图片ID  

            imageIds = new int[]{  

                R.drawable.a,     

                R.drawable.b,     

                R.drawable.c,     

                R.drawable.d,     

                R.drawable.e      

            };  

            //图片标题  

            titles = new String[]{  

                "巩俐不低俗，我就不能低俗",   

                "扑树又回来啦！再唱经典老歌引万人大合唱",    

                "揭秘北京电影如何升级",     

                "乐视网TV版大派送",      

                "热血屌丝的反杀"  

            };  

            //显示的图片  

            images = new ArrayList<ImageView>();  

            for(int i =0; i < imageIds.length; i++){  

                ImageView imageView = new ImageView(this);  

                imageView.setBackgroundResource(imageIds[i]);  

                images.add(imageView);  

            }  

            //显示的点  

            dots = new ArrayList<View>();  

            dots.add(findViewById(R.id.dot_0));  

            dots.add(findViewById(R.id.dot_1));  

            dots.add(findViewById(R.id.dot_2));  

            dots.add(findViewById(R.id.dot_3));  

            dots.add(findViewById(R.id.dot_4));  

            title = (TextView) findViewById(R.id.title);  

            title.setText(titles[0]);  

            mViewPager = (ViewPager) findViewById(R.id.vp);  

            adapter = new ViewPagerAdapter();   

            mViewPager.setAdapter(adapter);  

            mViewPager.setOnPageChangeListener(new OnPageChangeListener() {  

                @Override  

                public void onPageSelected(int position) {  

                    title.setText(titles[position]);  

                    dots.get(oldPosition).setBackgroundResource(R.drawable.dot_normal);  

                    dots.get(position).setBackgroundResource(R.drawable.dot_focused);  

                    oldPosition = position;  

                    currentItem = position;  

                }  

                @Override  

                public void onPageScrolled(int arg0, float arg1, int arg2) {  

                }  

                @Override  

                public void onPageScrollStateChanged(int arg0) {  

                }  

            });  

        }  

        private class ViewPagerAdapter extends PagerAdapter {  

            @Override  

            public int getCount() {  

                return images.size();  

            }  

            //是否是同一张图片  

            @Override  

            public boolean isViewFromObject(View arg0, Object arg1) {  

                return arg0 == arg1;  

            }  

            @Override  

            public void destroyItem(ViewGroup view, int position, Object object) {  

                view.removeView(images.get(position));  

            }  

            @Override  

            public Object instantiateItem(ViewGroup view, int position) {  

                view.addView(images.get(position));  

                return images.get(position);  

            }  

        }  

      

        @Override  

        protected void onStart() {  

            // TODO Auto-generated method stub  

            super.onStart();  

            scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();  

            //每隔2秒钟切换一张图片  

            scheduledExecutorService.scheduleWithFixedDelay(new ViewPagerTask(), 2, 2, TimeUnit.SECONDS);  

        }  

          

        //切换图片  

        private class ViewPagerTask implements Runnable {  

            @Override  

            public void run() {  

                currentItem = (currentItem +1) % imageIds.length;  

                //更新界面  

                handler.obtainMessage().sendToTarget();  

            }  

        }  

        private Handler handler = new Handler(){  

            @Override  

            public void handleMessage(Message msg) {  

                //设置当前页面  

                mViewPager.setCurrentItem(<span style="font-family: Arial, Helvetica, sans-serif;">currentItem</span><span style="font-family: Arial, Helvetica, sans-serif;">);</span>  

            }  

        };  

    }  

标签： 电商 推广

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