用最简单最实用的方式实现ViewPager无限循环两种方式

来源：互联网发布：淘宝上能买到av碟片吗编辑：程序博客网时间：2024/04/29 13:35

转载：http://blog.csdn.net/just_sanpark/article/details/17436037

先上效果：

第一种：

实现原理：

有三张图片，实现无限循环。在viewpager中设置5个view，第一个为三张图片的最后一张，第五张为三张图片的第一张。图片顺序如下数字：

2-0-1-2-0

0-1-2为正常的三个图片。2，0 为添加的两个图片view

滑动的顺序：进入页面显示0图片，向右滑动到0时,将0页设置为0，则可以继续向右滑动。同理当向左滑动到 2 时，将2页设置为2。

下面贴代码：

ViewpagerDemo.java

[java] view plaincopy

package com.example.demo;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
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;
public class ViewpagerDemo extends Activity implements OnPageChangeListener {
private ViewPager viewPager;
private List<ImageView> listviews;
private int[] pics = { R.drawable.xu1, R.drawable.xu2, R.drawable.xu3 };
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewpager);
viewPager = (ViewPager) findViewById(R.id.viewpager);
listviews = new ArrayList<ImageView>();
// 添加viewpager多出的两个view
int length = pics.length + 2;
for (int i = 0; i < length; i++) {
ImageView imageView = new ImageView(ViewpagerDemo.this);
ViewGroup.LayoutParams viewPagerImageViewParams = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.FILL_PARENT);
imageView.setLayoutParams(viewPagerImageViewParams);
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
listviews.add(imageView);
}
viewPager.setAdapter(new ViewPagerAdapter());
viewPager.setOnPageChangeListener(ViewpagerDemo.this);
// 设置viewpager在第二个视图显示
viewPager.setCurrentItem(1);
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageSelected(int i) {
int pageIndex = i;
if (i == 0) {
// 当视图在第一个时，将页面号设置为图片的最后一张。
pageIndex = pics.length;
} else if (i == pics.length + 1) {
// 当视图在最后一个是,将页面号设置为图片的第一张。
pageIndex = 1;
}
if (i != pageIndex) {
viewPager.setCurrentItem(pageIndex, false);
return;
}
}
class ViewPagerAdapter extends PagerAdapter {
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
ImageView view = listviews.get(position);
container.removeView(view);
view.setImageBitmap(null);
}
@Override
public Object instantiateItem(ViewGroup container, int i) {
if (i == 0) {
listviews.get(i).setImageResource(pics[2]);
} else if (i == (listviews.size() - 1)) {
listviews.get(i).setImageResource(pics[0]);
} else {
listviews.get(i).setImageResource(pics[i - 1]);
}
container.addView(listviews.get(i));
return listviews.get(i);
}
@Override
public int getCount() {
return listviews.size();
}
@Override
public boolean isViewFromObject(View view, Object o) {
return view == o;
}
}
<strong>}</strong>

第二种：
实现原理:在适配器中将getcount的值设置为无限大。然后将3份图片加载其中。

[java] view plaincopy

package com.example.demo;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
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;
public class ViewpagerDemo2 extends Activity {
private ViewPager viewPager;
private List<ImageView> listviews;
private int[] pics = { R.drawable.xu1, R.drawable.xu2, R.drawable.xu3 };
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewpager);
viewPager = (ViewPager) findViewById(R.id.viewpager);
listviews = new ArrayList<ImageView>();
for (int i = 0; i < pics.length; i++) {
ImageView imageView = new ImageView(ViewpagerDemo2.this);
ViewGroup.LayoutParams viewPagerImageViewParams = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.FILL_PARENT);
imageView.setLayoutParams(viewPagerImageViewParams);
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
imageView.setImageResource(pics[i]);
listviews.add(imageView);
}
viewPager.setAdapter(new ViewPagerAdapter());
viewPager.setCurrentItem(499);
}
class ViewPagerAdapter extends PagerAdapter {
@Override
public Object instantiateItem(ViewGroup container, int position) {
if (listviews.get(position % listviews.size()).getParent() != null) {
((ViewPager) listviews.get(position % listviews.size())
.getParent()).removeView(listviews.get(position
% listviews.size()));
}
((ViewPager) container).addView(
listviews.get(position % listviews.size()), 0);
return listviews.get(position % listviews.size());
}
@Override
public int getCount() {
return Integer.MAX_VALUE;
}
@Override
public boolean isViewFromObject(View view, Object o) {
return view == o;
}
}
}

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