Android 使用ViewPager实现左右循环滑动图片

ViewPager这个小demo实现的是可以左右循环滑动图片，下面带索引，滑到最后一页在往右滑动就要第一页，第一页往左滑动就到最后一页，先上效果图，用美女图片是我一贯的作风，呵呵

1. 首先看一些layout下的xml

使用ViewPager首先需要引入android-support-v4.jar这个jar包。自己不要忘记加

package com.example.viewpagerdemo; 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.view.ViewGroup.LayoutParams; import android.widget.ImageView; import android.widget.LinearLayout; public class TwoActivity extends Activity implements OnPageChangeListener{ /** * ViewPager */ private ViewPager viewPager; /** * 装点点的ImageView数组 */ private ImageView[] tips; /** * 装ImageView数组 */ private ImageView[] mImageViews; /** * 图片资源id */ private int[] imgIdArray ; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ViewGroup group = (ViewGroup)findViewById(R.id.viewGroup); viewPager = (ViewPager) findViewById(R.id.viewPager); //载入图片资源ID imgIdArray = new int[]{R.drawable.item01, R.drawable.item02, R.drawable.item03, R.drawable.item04, R.drawable.item05,R.drawable.item06, R.drawable.item07, R.drawable.item08}; //将点点加入到ViewGroup中 tips = new ImageView[imgIdArray.length]; for(int i=0; i<tips.length; i++){ ImageView imageView = new ImageView(this); imageView.setLayoutParams(new LayoutParams(10,10)); tips[i] = imageView; if(i == 0){ tips[i].setBackgroundResource(R.drawable.page_indicator_focused); }else{ tips[i].setBackgroundResource(R.drawable.page_indicator_unfocused); } LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(new ViewGroup.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); layoutParams.leftMargin = 5; layoutParams.rightMargin = 5; group.addView(imageView, layoutParams); } //将图片装载到数组中 mImageViews = new ImageView[imgIdArray.length]; for(int i=0; i<mImageViews.length; i++){ ImageView imageView = new ImageView(this); mImageViews[i] = imageView; imageView.setBackgroundResource(imgIdArray[i]); } //设置Adapter viewPager.setAdapter(new MyAdapter()); //设置监听，主要是设置点点的背景 viewPager.setOnPageChangeListener(this); //设置ViewPager的默认项, 设置为长度的100倍，这样子开始就能往左滑动 viewPager.setCurrentItem((mImageViews.length) * 100); } /** * * @author xiaanming * */ public class MyAdapter extends PagerAdapter{ @Override public int getCount() { return Integer.MAX_VALUE; } @Override public boolean isViewFromObject(View arg0, Object arg1) { return arg0 == arg1; } @Override public void destroyItem(View container, int position, Object object) { ((ViewPager)container).removeView(mImageViews[position % mImageViews.length]); } /** * 载入图片进去，用当前的position 除以图片数组长度取余数是关键 */ @Override public Object instantiateItem(View container, int position) { ((ViewPager)container).addView(mImageViews[position % mImageViews.length], 0); return mImageViews[position % mImageViews.length]; } } @Override public void onPageScrollStateChanged(int arg0) { } @Override public void onPageScrolled(int arg0, float arg1, int arg2) { } @Override public void onPageSelected(int arg0) { setImageBackground(arg0 % mImageViews.length); } /** * 设置选中的tip的背景 * @param selectItems */ private void setImageBackground(int selectItems){ for(int i=0; i<tips.length; i++){ if(i == selectItems){ tips[i].setBackgroundResource(R.drawable.page_indicator_focused); }else{ tips[i].setBackgroundResource(R.drawable.page_indicator_unfocused); } } } }

代码下载

上面的代码中，当只有3张图片或者2张图片的时候，滑动存在BUG问题的修改如下

destroyItem(View container, int position, Object object)方法中不removeView

@Override public void destroyItem(View container, int position, Object object) { // ((ViewPager)container).removeView(mImageViews[position % mImageViews.length]); }

instantiateItem(View container, int position)增加异常扑捉

@Override public Object instantiateItem(View container, int position) { try { ((ViewPager)container).addView(mImageViews[position % mImageViews.length], 0); }catch(Exception e){ //handler something } return mImageViews[position % mImageViews.length]; }