Viewpager 实现自动播放

代码如下

MainActivity.java

package com.example.vp_demo2;

import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;

import com.example.vp_demo2.adapter.MyPagerAdapter;
import com.example.vp_demo2.bean.News;

public class MainActivity extends Activity {
   ArrayList<News> newsList = new ArrayList<News>();
   private static final int FIRST_PAGE = 1;
   public static final int AUTO_SCROLL = 0;
   private int currentPosition;
   private LinearLayout ll_dots;
   private ViewPager viewPager;
   Handler handler = new Handler() {
       public void handleMessage(android.os.Message msg) {
           if (msg.what == AUTO_SCROLL) {
               // 获取当前viewPager所在索引值
               int currentItem = viewPager.getCurrentItem();
               // 让索引++
               currentItem++;
               // 重新设置给viewPager
               viewPager.setCurrentItem(currentItem);
               // 重新调用发送消息的方法
               handler.sendEmptyMessageDelayed(AUTO_SCROLL, 2000);
           }
       };
   };

   @SuppressWarnings("deprecation")
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       viewPager = (ViewPager) findViewById(R.id.viewPager);
       ll_dots = (LinearLayout) findViewById(R.id.ll_dots);
       // 初始化数据
       initData();
       // 初始化小点
       initDots();
       // 设置数据适配器
       viewPager.setAdapter(new MyPagerAdapter(this, newsList,handler));
       // 设置当前展示的位置为1  setCurrentItem 设置当前要轮播的viewpager
       viewPager.setCurrentItem(FIRST_PAGE);
       // 设置viewPager的监听事件
       viewPager.setOnPageChangeListener(new OnPageChangeListener() {
           // 滑动状态改变的方法 state :draaging 拖拽 idle 静止 settling 惯性过程
           @Override
           public void onPageScrollStateChanged(int state) {
               // 如果是静止状态,将当前页进行替换
               if (state == ViewPager.SCROLL_STATE_IDLE)
                   // 设置当前页,smoothScroll 平稳滑动
                   viewPager.setCurrentItem(currentPosition, false);
           }

           // 滑动过程中的方法 position 索引值
           // positionOffset 0-1
           // positionOffsetPixels 偏移像素值
           @Override
           public void onPageScrolled(int position, float positionOffset,
                   int positionOffsetPixels) {
           }

           // 选中某一页的监听
           @Override
           public void onPageSelected(int position) {
               if (position == newsList.size() - 1) {
                   // 设置当前值为1
                   currentPosition = FIRST_PAGE;
               } else if (position == 0) {
                   // 如果索引值为0了,就设置索引值为倒数第二个
                   currentPosition = newsList.size() - 2;
               } else {
                   currentPosition = position;
               }
               // 设置小点监听
               changeDots();
           }
       });

// 使用handler发送延时消息
handler.sendEmptyMessageDelayed(AUTO_SCROLL, 2000);

}

   //
   @Override
   protected void onDestroy() {
       super.onDestroy();
       // 移除所有回调和消息
       handler.removeCallbacksAndMessages(null);
   }

   private void changeDots() {
       int dotPosition = currentPosition - 1;
       // 设置小点监听
       for (int i = 0; i < ll_dots.getChildCount(); i++) {

           ImageView imageView = (ImageView) ll_dots.getChildAt(i);
           if (i == dotPosition) {
               // 从线性布局中取出对应小点,设置点亮
               imageView.setImageResource(R.drawable.image_select);
           } else {
               imageView.setImageResource(R.drawable.image);
           }
       }
   }

   private void initDots() {
       for (int i = 0; i < newsList.size() - 2; i++) {
           // 实例化ImageView
           ImageView imageView = new ImageView(this);
           // 如果是第一页,设置为选中图片
           if (i == 0) {
               imageView.setImageResource(R.drawable.image_select);
           } else {
               imageView.setImageResource(R.drawable.image);
           }
           // 代码中设置大小是指相对像素---px
           LayoutParams params = new LayoutParams(15, 15);

           params.setMargins(5, 5, 5, 5);
           // 添加到线性布局中
           ll_dots.addView(imageView, params);
       }
   }

private void initData() {

newsList.add(new News("我是第四个美女", R.drawable.a3)); // 0

       newsList.add(new News("我是第一个美女", R.drawable.a)); // 1
       newsList.add(new News("我是第二个美女", R.drawable.a1)); // 2
       newsList.add(new News("我是第三个美女", R.drawable.a2)); // 3
       newsList.add(new News("我是第四个美女", R.drawable.a3)); // 4

newsList.add(new News("我是第一个美女", R.drawable.a)); // 5
}

}
-----------------------------------------------------------------------------------------

MyPagerAdapter.java 代码

package com.example.vp_demo2.adapter;

import java.util.ArrayList;

import android.content.Context;
import android.os.Handler;
import android.support.v4.view.PagerAdapter;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.vp_demo2.MainActivity;
import com.example.vp_demo2.R;
import com.example.vp_demo2.bean.News;

public class MyPagerAdapter extends PagerAdapter {
   private final Context context;
   private final ArrayList<News> newsList;
   private final Handler handler;
   //构造方法
   public MyPagerAdapter(Context context, ArrayList<News> newsList,
           Handler handler) {
       this.handler = handler;
       this.context = context;
       this.newsList = newsList;
   }
   //统计循环的次数
   @Override
   public int getCount() {
       return newsList.size();
   }
   //当前的视图是否和instantiateItem所返回key对应的view是否一致
   @Override
   public boolean isViewFromObject(View view, Object object) {
       return view == object;
   }

   //初始化布局方法
   @Override
   public Object instantiateItem(ViewGroup container, int position) {
       // getView
       View view = View.inflate(context, R.layout.vp_item, null);
       ImageView imageView = (ImageView) view.findViewById(R.id.imageView);
       // 对ImageView设置触摸监听
       imageView.setOnTouchListener(new OnTouchListener() {

@Override
public boolean onTouch(View view, MotionEvent motionEvent) {

               switch (motionEvent.getAction()) {
               // 按下
               case MotionEvent.ACTION_DOWN:
                   // 取消handler任务
                   handler.removeCallbacksAndMessages(null);
                   break;
               // case MotionEvent.ACTION_MOVE:
               //
               // break;
               case MotionEvent.ACTION_UP:

               case MotionEvent.ACTION_CANCEL:
                   //重新执行handler轮播任务
                   handler.sendEmptyMessageDelayed(MainActivity.AUTO_SCROLL,
                           2000);
                   break;

               default:
                   break;
               }

               // true 代表是消费该事件
               // false 不消费
               return true;
           }
       });

TextView tv_title = (TextView) view.findViewById(R.id.tv_title);

       imageView.setImageResource(newsList.get(position).getResId());
       tv_title.setText(newsList.get(position).getTitle());
       // 添加到容器中
       container.addView(view);
       return view;
   }
   /**
   * 销毁条目
   * object 看instantiateItem中所返回的是不是view,如果是,可以直接移除object
   */
   @Override
   public void destroyItem(ViewGroup container, int position, Object object) {
       container.removeView((View) object);
   }

}
-----------------------------------------------------------------------------------------------------

News.java

package com.example.vp_demo2.bean;

public class News {
   private String title;

   private int resId;

   public String getTitle() {
       return title;
   }

   public void setTitle(String title) {
       this.title = title;
   }

   public int getResId() {
       return resId;
   }

   public void setResId(int resId) {
       this.resId = resId;
   }

   public News(String title, int resId) {
       super();
       this.title = title;
       this.resId = resId;
   }

   public News() {
       super();
       // TODO Auto-generated constructor stub
   }
   }

---------------------------------------------------------------------------------------------------------------------

activity_main.xml

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

</RelativeLayout>

----------------------------------------------------------

vp_item.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>

来源：oschina

链接：https://my.oschina.net/u/2663142/blog/3066710

标签

viewpager