Android 使用ViewPager实现轮播图效果

写这篇文章只是对今天所学的知识进行加深印象，对ViewPager的一些处理，比如适配器和各个方法的作用等。

先看效果图

这里我是在xml中写的圆点

Drawable文件夹下的xml代码：

Shape_yes.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
  <solid android:color="#ff6c67"></solid>
  <corners android:radius="1000dp"></corners>
</shape>

Shape_no.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#f0f0f0"></solid>
  <corners android:radius="1000dp"></corners>
</shape>

选择器

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/shape_no"
  android:state_selected="false"
  />
  <item android:drawable="@drawable/shape_yes"
   android:state_selected="true"
    />
</selector> 

Activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
  <RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="160dp">
    <android.support.v4.view.ViewPager
      android:id="@+id/vp"
      android:layout_width="match_parent"
      android:layout_height="wrap_content">
    </android.support.v4.view.ViewPager>
    <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="40dp"
      android:layout_alignParentBottom="true"
      android:gravity="center_horizontal"
      android:padding="5dp"
      android:orientation="vertical"
      android:background="#66000000">
      <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:gravity="center"
        android:orientation="horizontal"
        android:paddingBottom="10dp">
        <ImageView
          android:id="@+id/iv_one"
          android:layout_width="20dp"
          android:layout_height="20dp"
          android:layout_marginRight="20dp"
          android:background="@drawable/selector_show" />
        <ImageView
          android:id="@+id/iv_two"
          android:layout_width="20dp"
          android:layout_height="20dp"
          android:layout_marginRight="20dp"
          android:background="@drawable/selector_show" />
        <ImageView
          android:id="@+id/iv_three"
          android:layout_width="20dp"
          android:layout_height="20dp"
          android:background="@drawable/selector_show" />
      </LinearLayout>
    </LinearLayout>
  </RelativeLayout>
</RelativeLayout> 

写一个类ViewPagerAdapter_Circleextends PagerAdapter

public class ViewPagerAdapter_Circle extends PagerAdapter {
  ArrayList<View> arrayList;
  Context context;
  public ViewPagerAdapter_Circle(ArrayList<View> arrayList, Context context) {
    this.arrayList = arrayList;
    this.context = context;
  }
  /***数据源的大小（条目）*/
  @Override
  public int getCount() {
    return arrayList.size();
  }
  /**
   * 页面视图是否关联到特定的对象
   */
  @Override
  public boolean isViewFromObject(View view, Object object) {
    return view == object;//判断当前要显示的页面
  }
  /**
   * 初始化页面
   * 1.页面添加到container
   * 2.将页面返回
   */
  @Override
  public Object instantiateItem(ViewGroup container, int position) {
    container.addView(arrayList.get(position));//页面添加到container，添加位置
    return arrayList.get(position);
  }
  /**
   * 销毁当前页面
   */
  @Override
  public void destroyItem(ViewGroup container, int position, Object object) {
    container.removeView(arrayList.get(position));
  }
} 

MainActivity中代码（含注解）

public class MainActivity extends AppCompatActivity {
  ViewPager viewPager;
  int imageResIds[];
  ArrayList<View> imageViewList;//存图片的集合
  ArrayList<ImageView> imageViews;//存白点的集合
  ImageView iv_one,iv_two,iv_three;
  int oldPostion;//记录原来的位置
  private Boolean flag;
  int count=0;
  Handler handler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
      super.handleMessage(msg);
      if (msg.what == 0) {
        viewPager.setCurrentItem(count);
      }
    }
  };
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //初始化布局
    initView();
    //初始化数据
    initData();
    //设置适配器
    initAdapter();
    //设置圆点
    initPoint();
    flag = true;
//循环设置播放
    new Thread() {
      @Override
      public void run() {
        while (flag) {
          try {
            Thread.sleep(3000);
            count++;
            if (count == 3) {
              count = 0;
            }
          } catch (InterruptedException e) {
            e.printStackTrace();
          }
          /**传递信息*/
          Message msg = new Message();
          msg.what = 0;
          msg.obj = count;
          handler.sendMessage(msg);
        }
      }
    }.start();
  }
  private void initView() {
    viewPager = (ViewPager) findViewById(R.id.vp);
  }
  //初始化要显示的数据
  private void initData() {
    //图片资源数组
    imageResIds = new int[]{R.mipmap.a, R.mipmap.b, R.mipmap.c};
    imageViewList = new ArrayList<>();//存图片的集合
    ImageView imageView;
    for (int i = 0; i < imageResIds.length; i++) {
      imageView = new ImageView(this);
      imageView.setBackgroundResource(imageResIds[i]);
      imageViewList.add(imageView);
    }
  }
  //设置适配器
  private void initAdapter() {
    ViewPagerAdapter_Circle myViewPagerAdapter = new ViewPagerAdapter_Circle(imageViewList, this);
    viewPager.setAdapter(myViewPagerAdapter);
  }
  /**
   * 设置圆点的
   */
  private void initPoint() {
    iv_one = (ImageView) findViewById(R.id.iv_one);
    iv_two = (ImageView) findViewById(R.id.iv_two);
    iv_three = (ImageView) findViewById(R.id.iv_three);
    imageViews = new ArrayList<>();
    imageViews.add(iv_one);
    imageViews.add(iv_two);
    imageViews.add(iv_three);
    iv_one.setSelected(true);//设置第一个圆点为true
    /**viewPager监听事件*/
    viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
      /**滑动时调用*/
      @Override
      public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
      }
      /**停止时调用*/
      @Override
      public void onPageSelected(int position) {
        imageViews.get(position).setSelected(true);//滑动后颜色改变
        imageViews.get(oldPostion).setSelected(false);//变为初始颜色
        oldPostion = position;//把滑动后的圆点的position给原来的oldPostion
      }
        /**滑动状态改变时调用*/
      @Override
      public void onPageScrollStateChanged(int state) {
      }
    });
  }
} 

以上所述是小编给大家介绍的Android 使用ViewPager实现轮播图效果，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！