ViewPager+Handler实现图片自动轮播的效果

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/ViewPager_vp"
android:layout_width="match_parent"
android:layout_height="match_parent">

</android.support.v4.view.ViewPager>

package demo.viewpager;

import android.os.Bundle;
import android.os.Message;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;

import demo.viewpager.Utils.ViewPagerHandlerUtils;
import demo.viewpager.adapter.ViewPagerAdapter;

/**
* Created by 12406 on 2016/1/16.
*/
public class ViewPagerActivity extends AppCompatActivity {

private ViewPagerAdapter adapter;
private ViewPager viewPager;
private ViewPagerHandlerUtils handlerUtils;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_viewpager);
viewPager = (ViewPager) findViewById(R.id.ViewPager_vp);

init();
}

private void init() {
handlerUtils = new ViewPagerHandlerUtils(viewPager);
handlerUtils.sendEmptyMessageDelayed(handlerUtils.MSG_UPDATE, handlerUtils.MSG_DELAY);
adapter = new ViewPagerAdapter(this);
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}

@Override
public void onPageSelected(int position) {
handlerUtils.sendMessage(Message.obtain(handlerUtils, handlerUtils.MSG_PAGE, position, 0));
}

@Override
public void onPageScrollStateChanged(int state) {
switch (state) {
case ViewPager.SCROLL_STATE_DRAGGING:
handlerUtils.sendEmptyMessage(handlerUtils.MSG_KEEP);
break;
case ViewPager.SCROLL_STATE_IDLE:
handlerUtils.sendEmptyMessageDelayed(handlerUtils.MSG_UPDATE,
handlerUtils.MSG_DELAY);
}
}
});
}
}

package demo.viewpager.adapter;

import android.app.Activity;
import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.Toast;

import demo.viewpager.R;

/**
* Created by 12406 on 2016/1/16.
*/
public class ViewPagerAdapter extends PagerAdapter {
private Activity activity;
private int[] imager = new int[]{R.drawable.item1, R.drawable.item2, R.drawable.item3, R.drawable.item4, R.drawable.item5, R.drawable.item6};

public ViewPagerAdapter(Activity activity) {
this.activity = activity;
}

@Override
public int getCount() {
return Integer.MAX_VALUE;
}

@Override
public boolean isViewFromObject(View view, Object object) {
return view == object;
}

@Override
public void destroyItem(ViewGroup container, int position,
Object object) {
container.removeView((View) object);
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
position %= imager.length;
if (position < 0) {
position = imager.length + position;
}
ImageView imageView = new ImageView(activity);
imageView.setImageResource(imager[position]);
//        imageView.setScaleType(ImageView.ScaleType.FIT_XY);
final int finalPosition = position;
imageView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(activity, "第" + finalPosition + "个被点击了", Toast.LENGTH_SHORT).show();
}
});
container.addView(imageView);
return imageView;
}

}

package demo.viewpager.Utils;

import android.os.Handler;
import android.os.Message;
import android.support.v4.view.ViewPager;

public class ViewPagerHandlerUtils extends Handler {

/**
* 请求更新显示的ImageView。
*/
public static final int MSG_UPDATE = 1;
/**
* 请求暂停轮播。
*/
public static final int MSG_KEEP = 2;
/**
* 请求恢复轮播。
*/
public static final int MSG_BREAK = 3;
/**
* 记录最新的页号
*/
public static final int MSG_PAGE = 4;

//轮播间隔时间
public static final long MSG_DELAY = 2000;

private ViewPager mViewPager;
private int currentItem = 0;

public ViewPagerHandlerUtils(ViewPager viewPager) {
mViewPager = viewPager;
}

@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
if (mViewPager == null) {
return;
}
if (hasMessages(MSG_UPDATE)) {
removeMessages(MSG_UPDATE);
}
switch (msg.what) {
case MSG_UPDATE:
currentItem++;
mViewPager.setCurrentItem(currentItem);
sendEmptyMessageDelayed(MSG_UPDATE, MSG_DELAY);
break;
case MSG_KEEP:
break;
case MSG_BREAK:
sendEmptyMessageDelayed(MSG_UPDATE, MSG_DELAY);
break;
case MSG_PAGE:
currentItem = msg.arg1;
break;
default:
sendEmptyMessageDelayed(MSG_UPDATE, MSG_DELAY);
break;
}
}
}