Android实现单页显示3个Item的ViewPager炫酷切换效果

<FrameLayout
  android:layout_width="match_parent"
  android:layout_height="160dp"
  android:clipChildren="false"
  android:layout_centerInParent="true"
  android:background="#aadc71ff"
   
  <android.support.v4.view.ViewPager
    android:id="@+id/id_viewpager"
    android:layout_width="match_parent"
    android:layout_marginLeft="60dp"
    android:clipChildren="false"
    android:layout_marginRight="60dp"
    android:layout_height="120dp"
    android:layout_gravity="center"
     
  </android.support.v4.view.ViewPager 

</FrameLayout 

mViewPager.setPageMargin(20);//设置page间间距，自行根据需求设置
mViewPager.setOffscreenPageLimit(3);// =3
mViewPager.setAdapter...//写法不变

//setPageTransformer 决定动画效果
mViewPager.setPageTransformer(true, new RotateDownPageTransformer());

<?xml version="1.0" encoding="utf-8"? 
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:background="#aadc71ff"
  android:clipChildren="false"
  tools:context="com.example.administrator.banner2.MainActivity" 


  <android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    android:layout_width="match_parent"
    android:layout_height="150dp"
    android:layout_gravity="center"
    android:layout_marginBottom="10dp"
    android:layout_marginLeft="30dp"
    android:layout_marginRight="30dp"
    android:layout_marginTop="10dp"
    android:clipChildren="false" </android.support.v4.view.ViewPager 

  <LinearLayout
    android:id="@+id/dotLayout"
    android:layout_width="match_parent"
    android:layout_height="10dp"
    android:layout_gravity="bottom"
    android:layout_marginBottom="10dp"
    android:gravity="center"
    android:orientation="horizontal" </LinearLayout 

</FrameLayout 

import android.os.Bundle;
import android.os.Handler;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import com.zhy.magicviewpager.transformer.ScaleInTransformer;
import java.util.Timer;
import java.util.TimerTask;
public class MainActivity extends AppCompatActivity {
private ViewPager mViewPager;
private PagerAdapter mAdapter;
private LinearLayout dotLayout;
private Timer timer;
private Handler mHandler = new Handler();
private int prePosition = 0;
int[] imgRes = {R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.d,
R.drawable.e, R.drawable.f, R.drawable.g, R.drawable.h, R.drawable.i};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager = (ViewPager) findViewById(R.id.viewpager);
dotLayout = (LinearLayout) findViewById(R.id.dotLayout);
initDots();
mViewPager.setPageMargin(20);
mViewPager.setOffscreenPageLimit(3);
mViewPager.setAdapter(mAdapter = new PagerAdapter() {
@Override
public Object instantiateItem(ViewGroup container, int position) {
ImageView view = new ImageView(MainActivity.this);
view.setScaleType(ImageView.ScaleType.FIT_XY);
view.setImageResource(imgRes[position % imgRes.length]);
container.addView(view);
return view;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
@Override
public int getCount() {
return Integer.MAX_VALUE;
}
@Override
public boolean isViewFromObject(View view, Object o) {
return view == o;
}
});
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
dotLayout.getChildAt(prePosition).setEnabled(false);
dotLayout.getChildAt(position % imgRes.length).setEnabled(true);
prePosition = position % imgRes.length;
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
mViewPager.setPageTransformer(true, new ScaleInTransformer());
if (null != timer) {
timer.cancel();
}
timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
mHandler.post(new Runnable() {
@Override
public void run() {
mViewPager.setCurrentItem(mViewPager.getCurrentItem() + 1);
}
});
}
}, 0, 1000);
}
private void initDots() {
if (null != dotLayout) {
dotLayout.removeAllViews();
}
for (int i = 0; i < imgRes.length; i++) {
ImageView dot = new ImageView(this);
dot.setEnabled(false);
dot.setImageResource(R.drawable.dot);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
params.leftMargin = 10;
dot.setLayoutParams(params);
dotLayout.addView(dot);
}
dotLayout.getChildAt(0).setEnabled(true);
}
}

<?xml version="1.0" encoding="utf-8"? 
<selector xmlns:android="http://schemas.android.com/apk/res/android" 
<item android:state_enabled="true" 
<shape android:shape="rectangle" 
<size android:width="15dp" android:height="3dp" </size 
<corners android:radius="10dp" / 
<solid android:color="#ff0000" / 
</shape 
</item 
<item android:state_enabled="false" 
<shape android:shape="rectangle" 
<size android:width="15dp" android:height="3dp" </size 
<corners android:radius="10dp" / 
<solid android:color="#ffffff" / 
</shape 
</item 
</selector