208.m1-ViewPager的优化

最新推荐文章于 2025-07-10 17:12:17 发布

augfun

最新推荐文章于 2025-07-10 17:12:17 发布

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分类专栏： android整理

本文链接：https://blog.youkuaiyun.com/augfun/article/details/73011814

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本文介绍了一种优化安卓应用中HomeFragment图片展示的方法，通过改进HomePictureHolder类，实现了图片的高效加载和循环滑动效果，同时减少了内存占用。

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之前是依赖Fragment来实现填充，现在优化不依赖Fragment实现，测量的动作只需要在HomePictureHolder中实现就可以，之前实现的ViewPager每次画图的时候都是通过new ImageView(UiUtils.getContext());的方式来创建的，每次这样操作比较占空间，通过使用LinkedList这个链表来方便增删，同时对ViewPager的长度进行设置，可以实现无限的循环拖动.

res/values/demens.xml

<resources>

    <!-- Default screen margins, per the Android Design guidelines. -->
    <dimen name="activity_horizontal_margin">16dp</dimen>
    <dimen name="activity_vertical_margin">16dp</dimen>
    <dimen name="list_item_title_size">16dp</dimen>
    <dimen name="list_item_loadmore_height">40dp</dimen>
    <dimen name="list_item_margin">9dp</dimen>
    <dimen name="banner_picture_height">143dp</dimen>
    <dimen name="list_item_rating_height">14dp</dimen>
    <dimen name="app_detail_rating_margin">5dp</dimen>

</resources>

HomeFragment.java

package com.ldw.market.fragment;

import java.util.List;

import android.os.Bundle;
import android.text.format.Formatter;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.AbsListView;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.RatingBar;
import android.widget.TextView;

import com.ldw.market.R;
import com.ldw.market.Adapter.DefaultAdapter;
import com.ldw.market.domain.AppInfo;
import com.ldw.market.holder.BaseHolder;
import com.ldw.market.holder.HomePictureHolder;
import com.ldw.market.http.HttpHelper;
import com.ldw.market.protocol.GameProtocol;
import com.ldw.market.protocol.HomeProtocol;
import com.ldw.market.utils.UiUtils;
import com.ldw.market.utils.BitmapHelper;
import com.ldw.market.view.BaseListView;
import com.lidroid.xutils.BitmapUtils;
import com.lidroid.xutils.bitmap.PauseOnScrollListener;

/*
 * Home页面，主体的加载的几个页面和服务器请求数据都是在BaseFragment中去实现
 */
public class HomeFragment extends BaseFragment {

	private List<AppInfo> appInfos;//获取到app的集合
	private List<String> pictures;//获取到图片地址的集合

		// 当Fragment挂载的activity创建的时候调用
		@Override
		public void onActivityCreated(Bundle savedInstanceState) {
			super.onActivityCreated(savedInstanceState);
			show();
		}
	
	public View createSuccessView() {
		//使用自定义的ListView,ListView初始化的时候会初始化几个方法
		BaseListView listView = new BaseListView(UiUtils.getContext());
		
		//创建一个Holder
		HomePictureHolder pictureHolder = new HomePictureHolder();
		pictureHolder.setData(pictures);
		//获取到holder的view对象
		View contentView = pictureHolder.getContentView();
		//设置宽和高，方便画图
		//contentView.setLayoutParams(new AbsListView.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
		//把holder里面的view添加到ListView的上面
		listView.addHeaderView(contentView);
		
		listView.setAdapter(new HomeAdapter(appInfos));
		// 第二个参数 慢慢滑动的时候是否加载图片 false  加载   true 不加载
		//  第三个参数  飞速滑动的时候是否加载图片  true 不加载 
		listView.setOnScrollListener(new PauseOnScrollListener(bitmapUtils, false, true));
		bitmapUtils.configDefaultLoadingImage(R.drawable.ic_default);  // 设置如果图片加载中显示的图片
        bitmapUtils.configDefaultLoadFailedImage(R.drawable.ic_default);// 加载失败显示的图片
		return listView;
	}
	
	private class HomeAdapter extends DefaultAdapter<AppInfo>{

		//构造函数，初始化数据
		public HomeAdapter(List<AppInfo> appInfos) {
			super(appInfos);
			// TODO Auto-generated constructor stub
		}

		@Override
		protected BaseHolder<AppInfo> getHolder() {
			// TODO Auto-generated method stub
			return new ViewHolder();
		}

		//加载更多数据下拉条的实现
		@Override
		protected List<AppInfo> onload() {
			HomeProtocol protocol = new HomeProtocol();
			List<AppInfo> data = protocol.load(appInfos.size());
			appInfos.addAll(data);
			return data;
		}

		
		
	}
	
	static class ViewHolder extends BaseHolder<AppInfo>{
		ImageView item_icon;
		TextView item_title,item_size,item_bottom;
		RatingBar item_rating;

		
		//更新界面
		@Override
		public void refreshView(AppInfo data){
			this.item_title.setText(data.getName());// 设置应用程序的名字
			String size = Formatter.formatFileSize(UiUtils.getContext(), data.getSize());
			this.item_size.setText(size);
			this.item_bottom.setText(data.getDes());
			float stars = data.getStars();
			this.item_rating.setRating(stars); // 设置ratingBar的值
			String iconUrl = data.getIconUrl(); //这个地址不全，需要加上apache地址"iconUrl": "app/com.youyuan.yyhl/icon.jpg",
			//http://127.0.0.1:8090/image?name=app/com.youyuan.yyhl/icon.jpg
			
			
			//第一个参数是显示图片的控件，第二个参数是显示图片的url
			bitmapUtils.display(this.item_icon, HttpHelper.URL+"image?name="+iconUrl);
			// 显示图片的控件
			//bitmapUtils.display(holder.item_icon, HttpHelper.URL+"image?name="+iconUrl);
		}

		@Override
		public View initView() {
			View contentView = View.inflate(UiUtils.getContext(), R.layout.item_app, null);
			this.item_icon = (ImageView) contentView.findViewById(R.id.item_icon);
			this.item_title = (TextView) contentView.findViewById(R.id.item_title);
			this.item_size = (TextView) contentView.findViewById(R.id.item_size);
			this.item_bottom = (TextView) contentView.findViewById(R.id.item_bottom);
			this.item_rating = (RatingBar) contentView.findViewById(R.id.item_rating);
			return contentView;
		}

	}

	@Override
	public LoadResult load() {
		HomeProtocol protocol = new HomeProtocol();
		//获取到app的信息
		appInfos = protocol.load(0);
		pictures = protocol.getPictures();
		return checkData(appInfos);
	}
	

	
	
}

HomePictureHolder.java

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.View;
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());
		
	}
	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工具类

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);
		
	}


}