Android开发之使用ViewPager实现图片左右滑动切换效果

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package com.yztc.lx.homework;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.ViewGroup.LayoutParams;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import java.util.ArrayList;
import java.util.List;
/**
 * Created by Lx on 2016/8/6.
 */
public class Layout1Activity extends Activity {
  private ViewPager viewPager;
  private PagerAdapter adapter;
  private List viewPages = new ArrayList<>();
  //包裹点点的LinearLayout
  private ViewGroup group;
  private ImageView imageView;
  //定义一个ImageVIew数组，来存放生成的小园点
  private ImageView[] imageViews;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.layout1);
    initView();
    initPageAdapter();
    initPointer();
    initEvent();
  }
  //为控件绑定事件,绑定适配器
  private void initEvent() {
    viewPager.setAdapter(adapter);
    viewPager.addOnPageChangeListener(new GuidePageChangeListener());
  }
  //初始化ViewPager
  private void initPageAdapter() {
    /**
     * 对于这几个想要动态载入的page页面，使用LayoutInflater.inflate()来找到其布局文件，并实例化为View对象
     */
    LayoutInflater inflater = LayoutInflater.from(this);
    View page1 = inflater.inflate(R.layout.page1, null);
    View page2 = inflater.inflate(R.layout.page2, null);
    View page3 = inflater.inflate(R.layout.page3, null);
    //添加到集合中
    viewPages.add(page1);
    viewPages.add(page2);
    viewPages.add(page3);
    adapter = new PagerAdapter() {
      //获取当前界面个数
      @Override
      public int getCount() {
        return viewPages.size();
      }
      //判断是否由对象生成页面
      @Override
      public boolean isViewFromObject(View view, Object object) {
        return view == object;
      }
      @Override
      public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView(viewPages.get(position));
      }
      //返回一个对象，这个对象表明了PagerAdapter适配器选择哪个对象放在当前的ViewPager中
      @Override
      public Object instantiateItem(ViewGroup container, int position) {
        View view = viewPages.get(position);
        container.addView(view);
        return view;
      }
    };
  }
  //绑定控件
  private void initView() {
    viewPager = (ViewPager) findViewById(R.id.viewPager);
    group = (ViewGroup) findViewById(R.id.viewGroup);
  }
  //初始化下面的小圆点的方法
  private void initPointer() {
    //有多少个界面就new多长的数组
    imageViews = new ImageView[viewPages.size()];
    for (int i = 0; i