209.m1-banner的自动切换

banner的自动切换是利用hanndler，实现延迟执行，无线调用某个延迟执行的方法，实现一直循环执行延迟播放方法，同时，当点击的时候也需要把自动切换关闭，松开以后重新自动打开。需要注意的是ViewPager触摸时间的返回值是false,不拦截事件。

package com.ldw.market.holder;

import java.util.LinkedList;
import java.util.List;

import com.ldw.market.R;
import com.ldw.market.http.HttpHelper;
import com.ldw.market.utils.UiUtils;

import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.FrameLayout;
import android.view.ViewGroup.LayoutParams;
import android.widget.ImageView;

public class HomePictureHolder extends BaseHolder<List<String>> {

	//holder创建的时候调用下面的方法
	private ViewPager viewPager;
	private List<String> datas;
	@Override
	public View initView() {
		viewPager=new ViewPager(UiUtils.getContext());
		//给ViewPager设置布局的参数LayoutParames,宽度设置在res/values/demons.xml中
		viewPager.setLayoutParams(new AbsListView.LayoutParams(LayoutParams.MATCH_PARENT,UiUtils.getDimens(R.dimen.banner_picture_height)));
		return viewPager;
	}

	//holder中设置数据调用setData的掉用
	@Override
	public void refreshView(List<String> datas) {
		this.datas = datas;
		viewPager.setAdapter(new HomeAdapter());
		//当前条目的设置，实现“无限”滑动
		viewPager.setCurrentItem(1000*datas.size());
		/*
		runTask = new AuToRunTask();
		runTask.start();
		*/
		//当ViewPager按下的时候取消自动切换
		viewPager.setOnTouchListener(new OnTouchListener() {
			
			@Override
			public boolean onTouch(View v, MotionEvent event) {
				switch (event.getAction()) {
				case MotionEvent.ACTION_DOWN:
					runTask.stop();   
					break;
				case MotionEvent.ACTION_CANCEL:  // 事件的取消
				case MotionEvent.ACTION_UP:
					runTask.start();
					break;
				}
				
				return false; // viewPager 触摸事件 返回值要是false  
			}
		});
		runTask = new AuToRunTask();
		runTask.start();
	}
	
	
	boolean flag;
	private AuToRunTask runTask;
	//banner自动切换
	public class AuToRunTask implements Runnable{

		@Override
		public void run() {
			if(flag){
				//先取消之前的任务
				UiUtils.cancel(this);
				// 获取到ViewPager当前的条目
				int currentItem = viewPager.getCurrentItem();
				currentItem ++;
				viewPager.setCurrentItem(currentItem);
				// 延迟执行当前的任务
				UiUtils.postDelayed(this, 3000);
			}
			
		}
		//开始执行循环
		public void start(){
			//如果之前的停止的
			if(!flag){
				UiUtils.cancel(this);
				flag = true;
				//递归调用
				UiUtils.postDelayed(this, 3000);
			}
		}
		//停止
		public  void stop(){
			if(flag){
				flag=false;
				UiUtils.cancel(this);
			}
		}
		
	}
	
	class HomeAdapter extends PagerAdapter{
		//管理ImageView避免每次都new ImageView().LinkedList增删快速
		LinkedList<ImageView> convertView = new LinkedList<ImageView>();

		@Override
		public int getCount() {
			// 数目设置到最大，实现循环
			return Integer.MAX_VALUE;
		}

		@Override
		public boolean isViewFromObject(View arg0, Object arg1) {
			// TODO Auto-generated method stub
			return arg0==arg1;
		}
		
		@Override
		public void destroyItem(ViewGroup container, int position, Object object) {
			//uper.destroyItem(container, position, object);
			//移除的对象转化成ImageView对象
			ImageView view = (ImageView) object;
			//把移除的对象添加到缓存的集合中
			convertView.add(view);
			container.removeView((View)object);
		}

		@Override
		public Object instantiateItem(ViewGroup container, int position) {
			int index = position%datas.size();
			ImageView view;
			//如果缓存的集合不是空的就从集合中获取
			if(convertView.size() > 0){
				//获取到集合的第一个元素
				view = convertView.remove(0);
			}else{
				view = new ImageView(UiUtils.getContext());
			}
			//初始化imageView
			bitmapUtils.display(view, HttpHelper.URL+"image?name="+datas.get(index));
			container.addView(view);  //加载的view对象
			return view; // 返回的对象
		}
		
	}

}

UiUtils.java

package com.ldw.market.utils;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.drawable.Drawable;
import android.view.View;

import com.ldw.market.BaseApplication;

/*
 * 工具类，加载字符串
 */
public class UiUtils {

	/*
	 * 获取到字符数组 ，加载XML文件中的字符数组
	 * @param tabNames  字符数组的id
	 */
	public static String[] getStringArray(int tabNames) {
		return getResource().getStringArray(tabNames);
	}
	
	public static Resources getResource() {
		//获取资源
		return BaseApplication.getApplication().getResources();
	}
	
	public static Context getContext(){
		//获取到上下文
		return BaseApplication.getApplication();
	}
	
	/** dip转换px */
	public static int dip2px(int dip) {
		final float scale = getResource().getDisplayMetrics().density;
		return (int) (dip * scale + 0.5f);
	}

	/** pxz转换dip */

	public static int px2dip(int px) {
		final float scale = getResource().getDisplayMetrics().density;
		return (int) (px / scale + 0.5f);
	}
	
	//获取到res/values/demons.xml的配置参数
	public static int getDimens(int homePictureHeight) {
		return (int) getResource().getDimension(homePictureHeight);
	}
	
	/**
	 * 把Runnable 方法提交到主线程运行
	 * @param runnable
	 */
	public static void runOnUiThread(Runnable runnable) {
		// 在主线程运行
		if(android.os.Process.myTid()==BaseApplication.getMainTid()){
			runnable.run();
		}else{
			//获取主线程的handler  
			BaseApplication.getHandler().post(runnable);
		}
	}
	
	public static View inflate(int id) {
		return View.inflate(getContext(), id, null);
	}

	public static Drawable getDrawalbe(int id) {
		return getResource().getDrawable(id);
	}

	//延迟time时间执行task
	public static void postDelayed(Runnable run, int time) {
		// 获取到主线程的handler
		BaseApplication.getHandler().postDelayed(run, time);//调用runnable中的run方法
	}

	//取消一个任务
	public static void cancel(Runnable run) {
		// 获取到主线程的handler
		BaseApplication.getHandler().removeCallbacks(run);
		
	}


}