網上也有很多關於無限迴圈的實現方案，但是基本上都效果不是很好，沒有根本上利用和掌握ViewPager和Adapter的展現原理，也基本沒有複用View。

我這裡給大家講解下最新的無限迴圈的實現方案以及下圖這種縮放和透明度漸變的動畫PageTransformer的方案。

1、首先說無限迴圈，這個就要從PagerAdapter的下手。

 @Override
    public int getCount() {
        return mData.size() * 100;
    }

還有個關鍵位置：

int select = position < mData.size() ? position : (position % mData.size());

這裡要判斷處理下，如果position大於集合的大小的話，我們這個position要處理下，就是除以集合的大小取餘即可。

2、接下來給大家一個詳細的PagerAdapter的配置：

package com.tandong.viewpagerdemo;

import android.content.Context;
import android.support.v4.view.PagerAdapter;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.TextView;

import com.tandong.viewpagerdemo.R;

import java.util.ArrayList;
import java.util.List;

public class CardPagerAdapter extends PagerAdapter {

    private List<FrameLayout> mViews;
    private List<String> mData;
    private Context context;

    public CardPagerAdapter(Context context, List<String> list) {
        this.context = context;
        mViews = new ArrayList<FrameLayout>();
        this.mData = list;
        for (int i = 0; i < list.size(); i++) {
            mViews.add(null);
        }
    }

    @Override
    public int getCount() {
        return mData.size() * 100;
    }

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

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        View view = LayoutInflater.from(container.getContext())
                .inflate(R.layout.item_card, container, false);
        container.addView(view);
        FrameLayout frameLayout = (FrameLayout) view.findViewById(R.id.ll_container);
        ImageView iv_img = (ImageView) view.findViewById(R.id.iv_img);
        TextView tv_select = (TextView) view.findViewById(R.id.tv_select);
        int select = position < mData.size() ? position : (position % mData.size());
        Log.i("info", "位置：" + select + "  " + position + "  " + (position / mData.size()) + "  " + (position % mData.size()));
        tv_select.setText("" + select);
        mViews.set(select, frameLayout);
        return view;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((View) object);
        int select = position < mData.size() ? position : (position % mData.size());
        mViews.set(select, null);
    }

}
 

package com.tandong.viewpagerdemo;

import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.View;

public class TransFormer implements ViewPager.PageTransformer {
    public static float MIN_ALPHA = 0.5f;
    public static float MIN_SCALE = 0.8f;

    @Override
    public void transformPage(View page, float position) {
        if (position < -1 || position > 1) {
            page.setAlpha(MIN_ALPHA);
            page.setScaleX(MIN_SCALE);
            page.setScaleY(MIN_SCALE);
            Log.i("info", "縮放：position < -1 || position > 1");
        } else if (position <= 1) { // [-1,1]
            float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));
            if (position < 0) {
                float scaleX = 1 + 0.2f * position;
                Log.i("info", "縮放：position < 0");
                page.setScaleX(scaleX);
                page.setScaleY(scaleX);
            } else {
                float scaleX = 1 - 0.2f * position;
                page.setScaleX(scaleX);
                page.setScaleY(scaleX);
                Log.i("info", "縮放：position <= 1 >=0");
            }
            page.setAlpha(MIN_ALPHA + (scaleFactor - MIN_SCALE) / (1 - MIN_SCALE) * (1 - MIN_ALPHA));
        }
    }
}
 

package com.tandong.viewpagerdemo;

import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;

import com.tandong.viewpagerdemo.R;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private ViewPager vp;
    private CardPagerAdapter cardPagerAdapter;
    private List<String> lists;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {
        vp = (ViewPager) this.findViewById(R.id.vp);
        lists = new ArrayList<String>();
        for (int i = 0; i < 5; i++) {
            lists.add("");
        }
        cardPagerAdapter = new CardPagerAdapter(this, lists);
//        vp.setPageMargin(10);
        vp.setOffscreenPageLimit(3);
        vp.setPageTransformer(false, new TransFormer());
        vp.setAdapter(cardPagerAdapter);
        vp.setCurrentItem(cardPagerAdapter.getCount() / 2);
    }
}

android:clipChildren="false"

android:layout_marginLeft="80dp"
android:layout_marginRight="80dp"