android RSS reader

1. AndroidManifest.xml中的activity设置：

  <activity 
            android:name=".RSSMainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

2. RSSMainActivity:
1） 用ListView显示RSS Reader获取的数据结果
定义ListView的list layout 和 item layout
activity_postlist.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- activity_postlist.xml -->
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".RSSMainActivity" >
    
    <ListView
        android:id="@+id/postListView"
    	android:layout_width="fill_parent"
    	android:layout_height="fill_parent" /> 
</RelativeLayout>

postitem.xml: 显示RSS的title和pubDate

<?xml version="1.0" encoding="utf-8"?>
<!-- postitem.xml -->
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    android:paddingTop="5dp"
    android:paddingBottom="5dp"
    >
    
    <ImageView 
        android:id="@+id/postThumb"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:src="@drawable/ic_launcher"
        android:scaleType="centerCrop"
        android:layout_marginRight="5dp"/>

    <TextView
        android:id="@+id/postTitleLabel"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignTop="@id/postThumb"
        android:layout_toRightOf="@id/postThumb"
        android:maxLines="2"
        android:text="This is a good Post, I hope it will have 2 lines. Please give me 2 lines"
        android:textIsSelectable="false"
        android:textSize="14sp"
        android:ellipsize="end"/>
 
    <TextView
        android:id="@+id/postDateLabel"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignBottom="@id/postThumb"
        android:layout_toRightOf="@id/postThumb"
        android:maxLines="1"
        android:text="April 12, 2013"
        android:textSize="10sp"
        />
</RelativeLayout>

RSSMainActivity.java中，添加listview。

public class RSSMainActivity extends Activity {
	
	private ArrayList<PostData> listData = new ArrayList<PostData>();
	private PostItemAdapter itemAdapter;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		
		setContentView(R.layout.activity_postlist);
		
		ListView listView = (ListView) this.findViewById(R.id.postListView);
		itemAdapter = new PostItemAdapter(this,R.layout.postitem, listData);
		listView.setAdapter(itemAdapter);
	}
	
}

定义RSSFeed的Model

public class PostData {
	public String postThumbUrl;
	public String postTitle;
	public String postDate;

}

2） 自定义Adapter， 实现listView.setAdapter的方法

public class PostItemAdapter extends ArrayAdapter<PostData> {
	
	private Activity myContext;
	private ArrayList<PostData> datas;
	
	static class ViewHolder{
		TextView postTitleView;
		TextView postDateView;
		ImageView postThumbView;
	}
	
	public PostItemAdapter(Context context, int textViewResourceId, ArrayList<PostData> objects){
		super(context, textViewResourceId, objects);
		
		myContext = (Activity) context;
		datas = objects;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		
		ViewHolder viewHolder;
		
		if(convertView==null){
			LayoutInflater inflater = myContext.getLayoutInflater();
			convertView = inflater.inflate(R.layout.postitem, null);
			
			viewHolder = new ViewHolder();
			viewHolder.postThumbView = (ImageView) convertView.findViewById(R.id.postThumb);
			viewHolder.postTitleView = (TextView) convertView.findViewById(R.id.postTitleLabel);
			viewHolder.postDateView = (TextView) convertView.findViewById(R.id.postDateLabel);
			convertView.setTag(viewHolder);
		}else{
			viewHolder = (ViewHolder) convertView.getTag();
		}
		
		if(datas.get(position).postThumbUrl == null){
			viewHolder.postThumbView.setImageResource(R.drawable.ic_launcher);
		}
		
		viewHolder.postTitleView.setText(datas.get(position).postTitle);
		viewHolder.postDateView.setText(datas.get(position).postDate);
		
		return convertView;
		
	}

}

3） 使用AsyncTask从后台获取数据
在RSSMainActivity中定义AsyncTask， 使用HttpURLConnection获取数据，并解析显示在 list中

private enum RSSXMLTag{
		TITLE, DATE, LINK, CONTENT, GUID, IGNORETAG;
	}

	private class RSSDataController extends AsyncTask<String, Integer, ArrayList<PostData>>{
		
		private RSSXMLTag currentTag;
		
		

		@Override
		protected void onPostExecute(ArrayList<PostData> result) {
			
			for(int i=0;i<result.size();i++){
				listData.add(result.get(i));
			}
			itemAdapter.notifyDataSetChanged();
		}



		@Override
		protected ArrayList<PostData> doInBackground(String... params) {
			
			String urlStr = params[0];
			InputStream is = null;
			ArrayList<PostData> postDataList = new ArrayList<PostData>();
			
			try{
				URL url = new URL(urlStr);
				HttpURLConnection connection = (HttpURLConnection) url.openConnection();
				connection.setReadTimeout(10*1000);
				connection.setConnectTimeout(10*1000);
				connection.setRequestMethod("GET");
				connection.setDoInput(true);
				connection.connect();
				
				int response = connection.getResponseCode();
				Log.d("debug", "the response is:" + response);
				
				is = connection.getInputStream();
				
				XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
				factory.setNamespaceAware(true);
				XmlPullParser xpp = factory.newPullParser();
				xpp.setInput(is,null);
				
				int eventType = xpp.getEventType();
				PostData pdData = null;
				SimpleDateFormat dateFormat = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss zzz", Locale.ENGLISH);
				
				while (eventType!=XmlPullParser.END_DOCUMENT){
					if(eventType == XmlPullParser.START_DOCUMENT){
						
					}else if(eventType == XmlPullParser.START_TAG){
						
						if(xpp.getName().equals("item")){
							pdData = new PostData();
							currentTag = RSSXMLTag.IGNORETAG;
						}else if(xpp.getName().equals("title")){
							currentTag = RSSXMLTag.TITLE;
						}else if(xpp.getName().equals("link")){
							currentTag = RSSXMLTag.LINK;
						}else if(xpp.getName().equals("pubDate")){
							currentTag = RSSXMLTag.DATE;
						}
					}else if(eventType == XmlPullParser.END_TAG){
						if(xpp.getName().equals("item")){
							Date postDate = dateFormat.parse(pdData.postDate);
							pdData.postDate = (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).format(postDate);
							postDataList.add(pdData);
						}else{
							currentTag = RSSXMLTag.IGNORETAG;
						}
					}else if(eventType == XmlPullParser.TEXT){
						String content = xpp.getText();
						content = content.trim();
						Log.d("debug", content);
						
						if(pdData!=null){
							switch (currentTag){
							case TITLE:
								if(content.length()!=0){
									if(pdData.postTitle !=null){
										pdData.postTitle += content;
									}else{
										pdData.postTitle = content;
									}
								}
								break;
							case LINK:
								if(content.length()!=0){
									if(pdData.postThumbUrl!=null){
										pdData.postThumbUrl += content;
									}else{
										pdData.postThumbUrl = content;
									}
								}
								break;
							case DATE:
								if(content.length()!=0){
									if(pdData.postDate !=null){
										pdData.postDate += content;
									}else{
										pdData.postDate = content;
									}
								}
								break;
							default:
								break;
							}
						}
					}
					
					eventType = xpp.next();
				}
				
			}catch(MalformedURLException e){
				Log.e("malformedURL error", e.getLocalizedMessage());
			}catch(IOException e){
				Log.e("IO error", e.getLocalizedMessage());
			}catch(XmlPullParserException e){
				Log.e("XmlPullParser error", e.getLocalizedMessage());
			}
			catch (ParseException e) {
				Log.e("Parse error", e.getLocalizedMessage());
			}
			
			return postDataList;
		}
		
	}

在RSSMainActivity中启用onStart方法，在该方法中运行后台AsyncTask的服务

@Override
	protected void onStart() {

		super.onStart();
		
		RSSDataController task = new RSSDataController();
		String rssUrl = "http://10.4.251.146/igrp/rssfeed.rss";
		String[] params = new String[]{rssUrl};
		task.execute(params);
	}