最近看了一个AndroidQuery的框架，里面的Demo，有个界面，让博主很喜欢。左右滑动十分顺畅，手感很好，于是拿来和大家分享一下。先看一下效果图：
从图中可以看出，上面的布局是一个Layout里面嵌套有个ViewPager，ViewPager中包含着Fragment，Fragment的布局文件包含了一个简单的GridView，GridView的Item布局很简单，就是一个100*100大小的图片。好啦，先说这么多，然后咱们看代码吧。
最外层Activity的布局文件
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:gravity="center" android:text="Display 10x100 images from Picasa." /> <android.support.v4.view.ViewPager android:id="@+id/pager" android:layout_width="fill_parent" android:layout_height="fill_parent" > <android.support.v4.view.PagerTabStrip android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="top" /> </android.support.v4.view.ViewPager></LinearLayout>
相应的Activity的java文件：（使用了AndroidAnnotation框架）
/* * $filename: ImageLoadingPageGridActivity.java,v $ * $Date: 2014-5-3 $ * Copyright (C) ZhengHaibo, Inc. All rights reserved. * This software is Made by Zhenghaibo. */package edu.njupt.zhb;import org.androidannotations.annotations.AfterViews;import org.androidannotations.annotations.EActivity;import org.androidannotations.annotations.NoTitle;import org.androidannotations.annotations.ViewById;import android.support.v4.app.FragmentActivity;import android.support.v4.view.ViewPager;/* [email protected]: ZhengHaibo *web: http://blog.csdn.net/nuptboyzhb *mail: [email protected] *2014-5-3 Nanjing,njupt,China */@NoTitle@EActivity(R.layout.image_page_grid_activity)public class ImageLoadingPageGridActivity extends FragmentActivity{ @ViewById ViewPager pager; PageAdapter adapter; @AfterViews void afterViews(){ adapter = new PageAdapter(getSupportFragmentManager(),ImageLoadingPageGridActivity.this); pager.setAdapter(adapter); pager.setOffscreenPageLimit(3);//设置缓存视图的数目 }}
大家注意：setOffscreenPageLimit的参数设置，数目越大，缓存的越多，切换的时候，加载的越快。但，并不是越大越好，内存中缓存的越多，消耗的手机资源就越多。
下面看一下PageAdapter的代码
/* * $filename: PageAdapter.java,v $ * $Date: 2014-5-3 $ * Copyright (C) ZhengHaibo, Inc. All rights reserved. * This software is Made by Zhenghaibo. */package edu.njupt.zhb;import android.content.Context;import android.os.Bundle;import android.support.v4.app.Fragment;import android.support.v4.app.FragmentManager;import android.support.v4.app.FragmentStatePagerAdapter;import android.util.Log;import android.view.ViewGroup;/* [email protected]: ZhengHaibo *web: http://blog.csdn.net/nuptboyzhb *mail: [email protected] *2014-5-3 Nanjing,njupt,China */public class PageAdapter extends FragmentStatePagerAdapter { private static String[] topics = { "dog", "cat", "bird", "panda", "horse", "elephant", "bear", "butterfly", "monkey", "fish", "tiger", "chicken", "pig" }; Context context; public PageAdapter(FragmentManager fm, Context context) { super(fm); this.context = context; } @Override public Fragment getItem(int pos) { Log.d("primary", topics[pos]); Bundle args = new Bundle(); args.putString("topic", topics[pos]); ImageGridFragment fragment = (ImageGridFragment) Fragment.instantiate( context, ImageGridFragment.class.getName(), args); return fragment; } @Override public int getCount() { return topics.length; } @Override public CharSequence getPageTitle(int pos) { return topics[pos]; } @Override public void setPrimaryItem(ViewGroup container, int position, Object object) { Log.d("primary", topics[position]); ImageGridFragment fragment = (ImageGridFragment) object; fragment.init(); } @Override public void destroyItem(ViewGroup container, int position, Object object) { Log.d("destroyItem", topics[position]); }}
从上面的额PageAdapter的代码可以看出，里面总共有13个页面。也就是左右滑动的时候，有13个Fragment。这里，注意一下getItem方法，它返回的是一个ImageGridFragment，并且向该Fragment中传递了键为topic的键值对。
下面看一下对应的ImageGridFragment的java文件和布局文件：
package edu.njupt.zhb;import java.util.ArrayList;import java.util.List;import android.os.Bundle;import android.support.v4.app.Fragment;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import com.androidquery.AQuery;import com.androidquery.callback.AjaxStatus;import com.androidquery.util.AQUtility;import com.androidquery.util.XmlDom;public class ImageGridFragment extends Fragment { private AQuery aq; private AQuery aq2; private String topic; private List<Photo> photos; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.image_grid_fragment, container, false); aq = new AQuery(getActivity(), view); aq2 = new AQuery(getActivity()); Log.d("ViewPagerDemo","onCreateView..."); return view; } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); topic = getArguments().getString("topic"); Log.d("ViewPagerDemo","onActivityCreated..."); } private boolean inited; public void init() { if (aq == null || inited) return; inited = true; Log.d("ViewPagerDemo","init..."); refresh(); } public void refresh() { ajaxPhotos(); } private void ajaxPhotos() { String url = "https://picasaweb.google.com/data/feed/api/all?q=" + topic + "&max-results=100"; aq.progress(R.id.progress).ajax(url, XmlDom.class, 0, this, "photosCb"); } public void photosCb(String url, XmlDom xml, AjaxStatus status) { if (xml != null) { photos = convertAll(xml); render(photos); } } private void render(List<Photo> entries) { AQUtility.debug("render setup"); ArrayAdapter<Photo> aa = new ArrayAdapter<Photo>(getActivity(), R.layout.grid_item2, entries) { public View getView(int position, View convertView, ViewGroup parent) { if (convertView == null) { convertView = aq.inflate(convertView, R.layout.grid_item2, parent); } Photo photo = getItem(position); AQuery aq = aq2.recycle(convertView); String tbUrl = photo.tb; if (aq.shouldDelay(position, convertView, parent, tbUrl)) { aq.id(R.id.tb).clear(); } else { aq.id(R.id.tb).image(tbUrl, true, true, 200, R.drawable.image_missing, null, 0, 0); } return convertView; } }; aq.id(R.id.grid).adapter(aa); } private List<Photo> convertAll(XmlDom xml) { List<XmlDom> entries = xml.children("entry"); List<Photo> result = new ArrayList<Photo>(); for (XmlDom entry : entries) { result.add(convert(entry)); } return result; } private Photo convert(XmlDom xml) { String url = xml.child("content").attr("src"); String title = xml.child("title").text(); String author = xml.child("author").text("name"); String tb = url; List<XmlDom> tbs = xml.tags("media:thumbnail"); if (tbs.size() > 0) { // tb = tbs.get(0).attr("url"); tb = tbs.get(tbs.size() - 1).attr("url"); } tb = tb.replaceAll("https:", "http:"); Photo photo = new Photo(); photo.url = url; photo.tb = tb; photo.title = title; photo.author = author; return photo; } class Photo { String tb; String url; String title; String author; }}布局文件
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <GridView android:id="@+id/grid" android:layout_width="fill_parent" android:layout_height="fill_parent" android:columnWidth="90dp" android:numColumns="auto_fit" android:verticalSpacing="10dp" android:horizontalSpacing="10dp" android:stretchMode="columnWidth" android:gravity="center" /> <ProgressBar android:id="@+id/progress" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true" android:visibility="gone" /> </RelativeLayout>
注意：ImageGridFragment的init方法是在PageAdapter中调用的。本Demo中，init是直接使用AQuery从网络上获取相应的资源。而对于实际的项目，我们首先检查本地数据库是否有相应的资源，如果有，先加载。其次，向网络中获取，查看是否有更新，如有更新，就再在原来的基础上，添加数据。
整个项目中得比较关键的布局就这么多。整个项目下载地址：http://download.csdn.net/detail/nuptboyzhb/7287219
android开发联盟QQ群：272209595