CSDN客户端实现

本是古典何须时尚 2022-07-30 13:13 201阅读 0赞

### 本文主要讲解实现了一个CSDN的安卓客户端，主要知识点如下 ###

1.  java爬虫获取网页数据
2.  将java程序打包成jar包
3.  Fragment+viewpager+TabPageIndicator实现Tab效果
4.  gestureImageView实现放大缩小图片
5.  imageLodar实现异步加载图上
6.  XListView实现下拉刷新

### java爬虫获取网页资源 ###

package com.zhy.biz;  
    
    import java.util.ArrayList;  
    import java.util.List;  
    
    import org.jsoup.Jsoup;  
    import org.jsoup.nodes.Document;  
    import org.jsoup.nodes.Element;  
    import org.jsoup.select.Elements;  
    
    import com.zhy.bean.CommonException;  
    import com.zhy.bean.NewsItem;  
    import com.zhy.csdn.DataUtil;  
    import com.zhy.csdn.URLUtil;  
    
    /** 
     * 处理NewItem的业务类 
     * @author zhy 
     *  
     */  
    public class NewsItemBiz  
    {  
        /** 
         * 业界、移动、云计算 
         *  
         * @param htmlStr 
         * @return 
         * @throws CommonException  
         */  
        public List<NewsItem> getNewsItems( int newsType , int currentPage) throws CommonException  
        {  
            String urlStr = URLUtil.generateUrl(newsType, currentPage);  
    
            String htmlStr = DataUtil.doGet(urlStr);  
    
            List<NewsItem> newsItems = new ArrayList<NewsItem>();  
            NewsItem newsItem = null;  
    
            Document doc = Jsoup.parse(htmlStr);  
            Elements units = doc.getElementsByClass("unit");  
            for (int i = 0; i < units.size(); i++)  
            {  
                newsItem = new NewsItem();  
                newsItem.setNewsType(newsType);  
    
                Element unit_ele = units.get(i);  
    
                Element h1_ele = unit_ele.getElementsByTag("h1").get(0);  
                Element h1_a_ele = h1_ele.child(0);  
                String title = h1_a_ele.text();  
                String href = h1_a_ele.attr("href");  
    
                newsItem.setLink(href);  
                newsItem.setTitle(title);  
    
                Element h4_ele = unit_ele.getElementsByTag("h4").get(0);  
                Element ago_ele = h4_ele.getElementsByClass("ago").get(0);  
                String date = ago_ele.text();  
    
                newsItem.setDate(date);  
    
                Element dl_ele = unit_ele.getElementsByTag("dl").get(0);// dl  
                Element dt_ele = dl_ele.child(0);// dt  
                try  
                {// 可能没有图片  
                    Element img_ele = dt_ele.child(0);  
                    String imgLink = img_ele.child(0).attr("src");  
                    newsItem.setImgLink(imgLink);  
                } catch (IndexOutOfBoundsException e)  
                {  
    
                }  
                Element content_ele = dl_ele.child(1);// dd  
                String content = content_ele.text();  
                newsItem.setContent(content);  
                newsItems.add(newsItem);  
            }  
    
            return newsItems;  
    
        }  
    
    }

### 详细实现参见链接 ###

[抓取csdn上的各类别的文章 （制作csdn app 二） - Hongyang - 博客频道 - CSDN.NET][csdn_ _csdn app _ - Hongyang - _ - CSDN.NET]

### 将java项目打包成jar包 ###

参考链接：[在Eclipse中将Java项目打包为jar - 闵开慧的个人页面 - 开源中国社区][Eclipse_Java_jar - _ -]

### Fragment+viewpager+TabPageIndicator实现Tab效果 ###

package com.zhy.csdndemo;  
    
    
    import com.viewpagerindicator.TabPageIndicator;  
    
    
    import android.os.Bundle;  
    import android.support.v4.app.FragmentActivity;  
    import android.support.v4.app.FragmentPagerAdapter;  
    import android.support.v4.view.ViewPager;  
    
    
    public class MainActivity extends FragmentActivity  
    {
          
        private TabPageIndicator mIndicator ;  
        private ViewPager mViewPager ;  
        private FragmentPagerAdapter mAdapter ;  
    
    
        @Override  
        protected void onCreate(Bundle savedInstanceState)  
        {  
            super.onCreate(savedInstanceState);  
            setContentView(R.layout.activity_main);  
    
            mIndicator = (TabPageIndicator) findViewById(R.id.id_indicator);  
            mViewPager = (ViewPager) findViewById(R.id.id_pager);  
            mAdapter = new TabAdapter(getSupportFragmentManager());  
            mViewPager.setAdapter(mAdapter);  
            mIndicator.setViewPager(mViewPager, 0);  
    
    
    
        }  
    
    
    
    
    }

### 详细实现参见链接 ###

[Android 使用Fragment，ViewPagerIndicator 制作csdn app主要框架 - Hongyang - 博客频道 - CSDN.NET][Android _Fragment_ViewPagerIndicator _csdn app_ - Hongyang - _ - CSDN.NET]

### viewPager的适配器 ###

package com.zhy.csdndemo;
    
    import android.support.v4.app.Fragment;
    import android.support.v4.app.FragmentManager;
    import android.support.v4.app.FragmentPagerAdapter;
    
    public class TabAdapter extends FragmentPagerAdapter
    {
        
    
        public static final String[] TITLES = new String[] { "业界", "移动", "研发", "程序员杂志", "云计算" };
    
        public TabAdapter(FragmentManager fm)
        {
            super(fm);
        }
    
        @Override
        public Fragment getItem(int arg0)
        {
            MainFragment fragment = new MainFragment(arg0+1);
            return fragment;
        }
    
        @Override
        public CharSequence getPageTitle(int position)
        {
            return TITLES[position % TITLES.length];
        }
    
        @Override
        public int getCount()
        {
            return TITLES.length;
        }
    
    }

### viewPager中的Fragment实现，其中用xListView实现了获取数据与刷新等功能 ###

package com.zhy.csdndemo;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import me.maxwin.view.IXListViewLoadMore;
    import me.maxwin.view.IXListViewRefreshListener;
    import me.maxwin.view.XListView;
    import android.annotation.SuppressLint;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    
    import com.zhy.bean.CommonException;
    import com.zhy.bean.NewsItem;
    import com.zhy.biz.NewsItemBiz;
    import com.zhy.csdn.Constaint;
    import com.zhy.csdndemo.adapter.NewsItemAdapter;
    
    @SuppressLint("ValidFragment")
    public class MainFragment extends Fragment implements IXListViewRefreshListener, IXListViewLoadMore
    {
        
        /**
         * 默认的newType
         */
        private int newsType = Constaint.NEWS_TYPE_YEJIE;
        /**
         * 当前页面
         */
        private int currentPage = 1;
        /**
         * 处理新闻的业务类
         */
        private NewsItemBiz mNewsItemBiz;
        /**
         * 扩展的ListView
         */
        private XListView mXListView;
        /**
         * 数据适配器
         */
        private NewsItemAdapter mAdapter;
    
        /**
         * 数据
         */
        private List<NewsItem> mDatas = new ArrayList<NewsItem>();
    
        /**
         * 获得newType
         * @param newsType
         */
        public MainFragment(int newsType)
        {
            this.newsType = newsType;
            mNewsItemBiz = new NewsItemBiz();
        }
    
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {
            return inflater.inflate(R.layout.tab_item_fragment_main, null);
        }
    
        @Override
        public void onActivityCreated(Bundle savedInstanceState)
        {
            super.onActivityCreated(savedInstanceState);
            mAdapter = new NewsItemAdapter(getActivity(), mDatas);
            /**
             * 初始化
             */
            mXListView = (XListView) getView().findViewById(R.id.id_xlistView);
            mXListView.setAdapter(mAdapter);
            mXListView.setPullRefreshEnable(this);
            mXListView.setPullLoadEnable(this);
            //mXListView.NotRefreshAtBegin();
            /**
             * 进来时直接刷新
             */
            mXListView.startRefresh();
        }
    
        @Override
        public void onRefresh()
        {
            new LoadDatasTask().execute();
        }
    
        @Override
        public void onLoadMore()
        {
            // TODO Auto-generated method stub
    
        }
        /**
         * 记载数据的异步任务
         * @author zhy
         *
         */
        class LoadDatasTask extends AsyncTask<Void, Void, Void>
        {
    
            @Override
            protected Void doInBackground(Void... params)
            {
                try
                {
                    List<NewsItem> newsItems = mNewsItemBiz.getNewsItems(newsType, currentPage);
                    mDatas = newsItems;
                } catch (CommonException e)
                {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
    
                return null;
            }
    
            @Override
            protected void onPostExecute(Void result)
            {
                mAdapter.addAll(mDatas);
                mAdapter.notifyDataSetChanged();
                mXListView.stopRefresh();
            }
    
        }
    
    }

### xListView的adapter,其中使用了imageLoder ###

package com.zhy.csdndemo.adapter;
    
    import java.util.List;
    
    import android.content.Context;
    import android.util.Log;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.BaseAdapter;
    import android.widget.ImageView;
    import android.widget.TextView;
    
    import com.nostra13.universalimageloader.core.DisplayImageOptions;
    import com.nostra13.universalimageloader.core.ImageLoader;
    import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
    import com.nostra13.universalimageloader.core.display.FadeInBitmapDisplayer;
    import com.nostra13.universalimageloader.core.display.RoundedBitmapDisplayer;
    import com.zhy.bean.NewsItem;
    import com.zhy.csdn.DataUtil;
    import com.zhy.csdndemo.R;
    
    public class NewsItemAdapter extends BaseAdapter
    {
    
        private LayoutInflater mInflater;
        private List<NewsItem> mDatas;
    
        /**
         * 使用了github开源的ImageLoad进行了数据加载
         */
        private ImageLoader imageLoader = ImageLoader.getInstance();
        private DisplayImageOptions options;
    
        public NewsItemAdapter(Context context, List<NewsItem> datas)
        {
            this.mDatas = datas;
            mInflater = LayoutInflater.from(context);
    
            imageLoader.init(ImageLoaderConfiguration.createDefault(context));
            options = new DisplayImageOptions.Builder().showStubImage(R.drawable.images)
                    .showImageForEmptyUri(R.drawable.images).showImageOnFail(R.drawable.images).cacheInMemory()
                    .cacheOnDisc().displayer(new RoundedBitmapDisplayer(20)).displayer(new FadeInBitmapDisplayer(300))
                    .build();
        }
    
        public void addAll(List<NewsItem> mDatas)
        {
            this.mDatas.addAll(mDatas);
        }
    
        @Override
        public int getCount()
        {
            return mDatas.size();
        }
    
        @Override
        public Object getItem(int position)
        {
            return mDatas.get(position);
        }
    
        @Override
        public long getItemId(int position)
        {
            return position;
        }
    
        @Override
        public View getView(int position, View convertView, ViewGroup parent)
        {
            ViewHolder holder = null;
            if (convertView == null)
            {
                convertView = mInflater.inflate(R.layout.news_item_yidong, null);
                holder = new ViewHolder();
    
                holder.mContent = (TextView) convertView.findViewById(R.id.id_content);
                holder.mTitle = (TextView) convertView.findViewById(R.id.id_title);
                holder.mDate = (TextView) convertView.findViewById(R.id.id_date);
                holder.mImg = (ImageView) convertView.findViewById(R.id.id_newsImg);
    
                convertView.setTag(holder);
            } else
            {
                holder = (ViewHolder) convertView.getTag();
            }
            NewsItem newsItem = mDatas.get(position);
            holder.mTitle.setText(DataUtil.ToDBC(newsItem.getTitle()));
            holder.mContent.setText(newsItem.getContent());
            holder.mDate.setText(newsItem.getDate());
            if (newsItem.getImgLink() != null)
            {
                holder.mImg.setVisibility(View.VISIBLE);
                imageLoader.displayImage(newsItem.getImgLink(), holder.mImg, options);
            } else
            {
                holder.mImg.setVisibility(View.GONE);
            }
    
            return convertView;
        }
    
        private final class ViewHolder
        {
            TextView mTitle;
            TextView mContent;
            ImageView mImg;
            TextView mDate;
        }
    
    }

### 参考链接： ###

[客户端上显示csdn上的各类别下的的文章列表 （制作csdn app 三） - Hongyang - 博客频道 - CSDN.NET][csdn_ _csdn app _ - Hongyang - _ - CSDN.NET 1]

### 效果如下 ###

![这里写图片描述][20160417202355024]

[csdn_ _csdn app _ - Hongyang - _ - CSDN.NET]: http://blog.csdn.net/lmj623565791/article/details/23532797
[Eclipse_Java_jar - _ -]: http://my.oschina.net/mkh/blog/265542?fromerr=98uL1b2Y
[Android _Fragment_ViewPagerIndicator _csdn app_ - Hongyang - _ - CSDN.NET]: http://blog.csdn.net/lmj623565791/article/details/23513993
[csdn_ _csdn app _ - Hongyang - _ - CSDN.NET 1]: http://blog.csdn.net/lmj623565791/article/details/23597229
[20160417202355024]: /images/20220724/307335455b5746a1800e69150a206f57.png