Android 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.List; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.os.Handler; 
import android.os.Message; 
import android.os.SystemClock; 
import android.support.v4.view.PagerAdapter; 
import android.support.v4.view.ViewPager; 
import android.support.v4.view.ViewPager.OnPageChangeListener; 
import android.util.Log; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.ImageView; 
import android.widget.LinearLayout; 
import android.widget.LinearLayout.LayoutParams; 
import android.widget.TextView; 
 
public class MainActivity extends Activity implements OnPageChangeListener { 
  
 protected static final String TAG = "MainActivity"; 
 private List<ImageView> imageViewList; 
 private ViewPager mViewPager; 
 private final int[] imageResIDs = { 
   R.drawable.a, 
   R.drawable.b, 
   R.drawable.c, 
   R.drawable.d, 
   R.drawable.e 
 }; 
 private final String[] imageDescriptions = { 
   "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", 
   "热血潘康姆瓷" 
 }; 
 private TextView tvImageDescription; // 图片描述 
 private LinearLayout llPointGroup;  // 点控件的组 
 private int previousPosition = 0;  // viewpager选中的前一个position 
 private boolean isStop = false; // 控制循环的子线程是否停止 
  
 private Handler handler = new Handler(){ 
 
  @Override 
  public void handleMessage(Message msg) { 
   super.handleMessage(msg); 
    
   mViewPager.setCurrentItem(mViewPager.getCurrentItem() + 1); 
  } 
 }; 
 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
   
  initView(); 
   
  new Thread(new Runnable() { 
 
   @Override 
   public void run() { 
    // 每两秒钟向主线程发送一条消息, 切换viewpager的界面 
    while(!isStop) { 
     SystemClock.sleep(2000); 
      
     handler.sendEmptyMessage(0); 
    } 
    Log.i(TAG, "循环线程停止了"); 
   }}).start(); 
 } 
  
 @Override 
 protected void onDestroy() { 
  isStop = true; 
  super.onDestroy(); 
 } 
 
 private void initView() { 
  mViewPager = (ViewPager) findViewById(R.id.viewpager); 
  llPointGroup = (LinearLayout) findViewById(R.id.ll_point_group); 
  tvImageDescription = (TextView) findViewById(R.id.tv_image_description); 
   
  imageViewList = new ArrayList<ImageView>(); 
   
  ImageView iv; 
  View pointView; 
  LayoutParams params; 
  for (int i = 0; i < imageResIDs.length; i++) { 
   iv = new ImageView(this); 
   iv.setBackgroundResource(imageResIDs[i]); 
   imageViewList.add(iv); 
    
   // 根据图片添加点 
   pointView = new View(this); 
   params = new LayoutParams(5, 5); 
   params.leftMargin = 5; 
   pointView.setLayoutParams(params); 
   pointView.setEnabled(false); 
   pointView.setBackgroundResource(R.drawable.point_bg); 
   llPointGroup.addView(pointView); 
  } 
   
  MyPagerAdapter mAdapter = new MyPagerAdapter(); 
  mViewPager.setAdapter(mAdapter); 
  mViewPager.setOnPageChangeListener(this); 
   
  int item = (Integer.MAX_VALUE / 2) - ((Integer.MAX_VALUE / 2) % imageViewList.size()); 
  mViewPager.setCurrentItem(item);  // 设置当前选中的item的position 
   
  tvImageDescription.setText(imageDescriptions[previousPosition]); 
  llPointGroup.getChildAt(previousPosition).setEnabled(true); // 第一点被选中 
 } 
  
  
 class MyPagerAdapter extends PagerAdapter { 
 
  @Override 
  public int getCount() { 
   return Integer.MAX_VALUE; 
  } 
 
  /** 
   * 移动的对象和进来的对象如果是同一个就返回true, 代表复用view对象 
   * false 使用object对象 
   */ 
  @Override 
  public boolean isViewFromObject(View arg0, Object arg1) { 
   return arg0 == arg1; 
  } 
 
  /** 
   * 需要销毁的对象的position传进来 
   */ 
  @Override 
  public void destroyItem(ViewGroup container, int position, Object object) { 
   // 移除掉指定position的对象 
   mViewPager.removeView(imageViewList.get(position % imageViewList.size())); 
  } 
 
  /** 
   * 加载position位置的view对象 
   */ 
  @Override 
  public Object instantiateItem(ViewGroup container, int position) { 
   // 添加指定position的对象 
   mViewPager.addView(imageViewList.get(position % imageViewList.size())); 
   return imageViewList.get(position % imageViewList.size()); 
  } 
 } 
 
 
 @Override 
 public void onPageScrollStateChanged(int arg0) { 
  // TODO Auto-generated method stub 
   
 } 
 
 @Override 
 public void onPageScrolled(int arg0, float arg1, int arg2) { 
  // TODO Auto-generated method stub 
   
 } 
 
 /** 
  * 当viewpager页面切换时回调 
  * @param position 就是当前显示的page页 
  */ 
 @Override 
 public void onPageSelected(int position) { 
  tvImageDescription.setText(imageDescriptions[position % imageViewList.size()]); 
  llPointGroup.getChildAt(position % imageViewList.size()).setEnabled(true); 
  llPointGroup.getChildAt(previousPosition).setEnabled(false); 
   
  previousPosition = position % imageViewList.size(); 
 } 
} 

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持编程小技巧。

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