Android實(shí)現(xiàn)圖片自動(dòng)切換功能(實(shí)例代碼詳解)

<?xml version="1.0" encoding="utf-8"?>
<ScrollView
 android:layout_height="match_parent"
 android:layout_width="match_parent"
 android:orientation="vertical"
 xmlns:android="http://schemas.android.com/apk/res/android">
 <RelativeLayout
  android:layout_width="match_parent"
  android:layout_height="match_parent">
  <FrameLayout
   android:layout_width="match_parent"
   android:layout_height="250dp"
   android:padding="20dp"
   android:orientation="vertical">
   <androidx.viewpager.widget.ViewPager
    android:id="@+id/viewContent"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>
   <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="25dp"
    android:orientation="horizontal"
    android:layout_gravity="bottom"
    android:gravity="center"
    android:layout_marginTop="5dp"
    android:background="#E6E6E6">
    <View
     android:id="@+id/p1"
     android:layout_width="5dp"
     android:layout_height="5dp"
     android:layout_marginLeft="2dp"
     android:layout_marginRight="2dp"
     android:background="@drawable/dot_focus"/>
    <View
     android:id="@+id/p2"
     android:layout_width="5dp"
     android:layout_height="5dp"
     android:layout_marginLeft="2dp"
     android:layout_marginRight="2dp"
     android:background="@drawable/dot_normal"/>
    <View
     android:id="@+id/p3"
     android:layout_width="5dp"
     android:layout_height="5dp"
     android:layout_marginLeft="2dp"
     android:layout_marginRight="2dp"
     android:background="@drawable/dot_normal"/>
   </LinearLayout>
  </FrameLayout>
 </RelativeLayout>
</ScrollView>

<?xml version="1.0" encoding="utf-8"?>
<shape android:shape="oval"
 xmlns:android="http://schemas.android.com/apk/res/android">
 <corners android:radius="5dp"/>
 <solid android:color="@color/white"/>
</shape>

<?xml version="1.0" encoding="utf-8"?>
<shape android:shape="oval"
 xmlns:android="http://schemas.android.com/apk/res/android">
 <corners android:radius="5dp"/>
 <solid android:color="@color/blue"/>
</shape>

public class MainActivity extends AppCompatActivity {
 private ArrayList<ImageView> imageViews= new ArrayList<>();
 private ArrayList<View>dots=new ArrayList<>();
 private ViewPager vp;
 private int image[]={R.drawable.denglu,R.drawable.disanye,R.drawable.hhh};
 private int oldPosition=0;
 private int currentItem;
 private ScheduledExecutorService scheduledExecutorService;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  //獲取圖片資源
  for (int i=0;i<image.length;i++){
   ImageView imageView=new ImageView(this);
   imageView.setImageResource(image[i]);
   imageViews.add(imageView);
  }
  //顯示的點(diǎn)的集合
  dots.add(findViewById(R.id.p1));
  dots.add(findViewById(R.id.p2));
  dots.add(findViewById(R.id.p3));

  vp=findViewById(R.id.viewContent);
  vp.setAdapter(new ViewPagerAdapter());
  vp.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
   @Override
   public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

   }

   @Override
   public void onPageSelected(int position) {
    //點(diǎn)的效果切換
    dots.get(oldPosition).setBackgroundResource(R.drawable.dot_normal);
    dots.get(position).setBackgroundResource(R.drawable.dot_fouced);
    oldPosition=position;
    currentItem=position;
   }

   @Override
   public void onPageScrollStateChanged(int state) {

   }
  });
 }

 class ViewPagerAdapter extends PagerAdapter {
  @Override
  public int getCount() {
   return imageViews.size();
  }

  @Override
  public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
   return view==object;
  }

  @Override
  public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
   View v=imageViews.get(position);
   container.removeView(v);
  }

  @NonNull
  @Override
  public Object instantiateItem(@NonNull ViewGroup container, int position) {
   View v=imageViews.get(position);
   container.addView(v);
   return v;
  }
 }

 @Override
 protected void onStart() {
  super.onStart();
  scheduledExecutorService= Executors.newSingleThreadScheduledExecutor();
  scheduledExecutorService.scheduleWithFixedDelay(new ViewPagerTask(),2,2, TimeUnit.SECONDS);
 }
 class ViewPagerTask implements Runnable{

  @Override
  public void run() {
   currentItem=(currentItem+1)%image.length;
   handler.obtainMessage().sendToTarget();
  }
 }
 Handler handler=new Handler(){
  @Override
  public void handleMessage(@NonNull Message msg) {
   vp.setCurrentItem(currentItem);
  }
 };
}