Android开发之使用ViewPager实现图片左右滑动切换效果

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical"
  >
  <ImageView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scaleType="centerCrop"
    android:src="@mipmap/view1"/>
</LinearLayout>

<?xml version="1.0" encoding="UTF-8"?>
<RelativeLayout android:orientation="vertical"
android:layout_height="match_parent"
android:layout_width="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<!-- 切换卡 -->
<android.support.v4.view.ViewPager
  android:layout_height="wrap_content"
  android:layout_width="match_parent"
  android:id="@+id/viewPager"></android.support.v4.view.ViewPager>
<!-- 点点 -->
<LinearLayout
  android:orientation="horizontal"
  android:layout_height="wrap_content"
  android:layout_width="fill_parent"
  android:id="@+id/viewGroup"
  android:layout_alignParentBottom="true"
  android:gravity="center_horizontal"
  android:layout_marginBottom="40dp"></LinearLayout>
</RelativeLayout>

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<View> 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 < imageViews.length; i++) {
      imageView = new ImageView(this);
      //设置控件的宽高
      imageView.setLayoutParams(new LayoutParams(25, 25));
      //设置控件的padding属性
      imageView.setPadding(20, 0, 20, 0);
      imageViews[i] = imageView;
      //初始化第一个page页面的图片的原点为选中状态
      if (i == 0) {
        //表示当前图片
        imageViews[i].setBackgroundResource(R.mipmap.page_indicator_focused);
        /**
         * 在java代码中动态生成ImageView的时候
         * 要设置其BackgroundResource属性才有效
         * 设置ImageResource属性无效
         */
      } else {
        imageViews[i].setBackgroundResource(R.mipmap.page_indicator_unfocused);
      }
      group.addView(imageViews[i]);
    }
  }
  //ViewPager的onPageChangeListener监听事件，当ViewPager的page页发生变化的时候调用
  public class GuidePageChangeListener implements ViewPager.OnPageChangeListener {
    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    }
    //页面滑动完成后执行
    @Override
    public void onPageSelected(int position) {
      //判断当前是在那个page，就把对应下标的ImageView原点设置为选中状态的图片
      for (int i = 0; i < imageViews.length; i++) {
        imageViews[position].setBackgroundResource(R.mipmap.page_indicator_focused);
        if (position != i) {
          imageViews[i].setBackgroundResource(R.mipmap.page_indicator_unfocused);
        }
      }
    }
    //监听页面的状态，0--静止 1--滑动  2--滑动完成
    @Override
    public void onPageScrollStateChanged(int state) {
    }
  }
}