Android巧用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：

1、首先看一些layout下的xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical" > 

  <android.support.v4.view.ViewPager
    android:id="@+id/viewPager"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" />  

  <RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical" >  

    <LinearLayout
      android:id="@+id/viewGroup"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:layout_alignParentBottom="true"
      android:layout_marginBottom="30dp"
      android:gravity="center_horizontal"
      android:orientation="horizontal" >
    </LinearLayout>
  </RelativeLayout>  

</FrameLayout> 

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);
      }
    }
  } 

} 

源码下载：左右滑动ViewPager

2、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];
  }

以上就是本文的全部内容，希望对大家学习Android软件编程有所帮助。