viewpager实现轮播图效果

在很多app中我们都有轮播图的效果,特别是一些电商类的app,大部分都有此功能,今天就简单的模仿下,还有一个自动跳动的小功能,这个用定时器实现就行,话不多说直接上代码:

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(1);
		}
	};
}

效果图：