如何合併，創建標籤並按升序排列更多RSS Feed鏈接的提要，例如Yahoo Pipes？

Question

我需要接收更多RSS Feed網址的供稿，我必須按降序彙總並顯示新聞。

某些鏈接沒有xml標籤<category>，所以我需要創建一個：我必須知道Feed的來源，以便我可以對它們進行分類。

這就是我想要實現：（爲源n 2我指的是類）

[！[在這裏輸入的形象描述] [1] [1]

我用使用Yahoo!Pipes進行所有這些更改。

我的嘗試是爲每個網址創建一個CustomListView，然後一次執行所有的AsyncTasks，但這不能正常工作 - 饋送不按升序顯示。

MainActivity

public class MainActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener { 
    private RSSFeed myRssFeed = null; 
    String[] urlFeed = {"url1", "url2"}; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     for (int i = 0; i < urlFeed.length; i++) { 
      News news = new News(i); 
      news.execute(); 
     } 
    } 

    @Override 
    public void onRefresh() { 
     for (int i = 0; i < urlFeed.length; i++) { 
      News news = new News(i); 
      news.execute(); 
     } 
    } 

    private class News extends AsyncTask<Object, Void, Void> { 
     protected int number; 
     public News(int urlNumber) { 
      number = urlNumber; 
     } 

     @Override 
     protected Void doInBackground(Object... arg0) { 

      String data = ""; 
      InputStream iStream; 

      try{ 
       URL url = new URL(urlFeed[number]); 

       // Creating an http connection to communicate with url 
       HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); 

       // Connecting to url 
       urlConnection.connect(); 

       // Reading data from url 
       iStream = urlConnection.getInputStream(); 

       BufferedReader br = new BufferedReader(new InputStreamReader(iStream)); 

       StringBuilder sbf = new StringBuilder(); 

       String line; 
       while((line = br.readLine()) != null){ 
        sbf.append(line); 
       } 

       data = sbf.toString(); 

       br.close(); 

       SAXParserFactory mySAXParserFactory = SAXParserFactory.newInstance(); 
       SAXParser mySAXParser = mySAXParserFactory.newSAXParser(); 
       XMLReader myXMLReader = mySAXParser.getXMLReader(); 
       RSSHandler myRSSHandler = new RSSHandler(); 
       myXMLReader.setContentHandler(myRSSHandler); 
       InputSource myInputSource = new InputSource(url.openStream()); 
       myXMLReader.parse(myInputSource); 

       myRssFeed = myRSSHandler.getFeed(); 

      } catch (ParserConfigurationException | IOException | SAXException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 

      return null; 
     } 

     @Override 
     protected void onPostExecute(Void result) { 
      super.onPostExecute(result); 

      if (myRssFeed != null) { 

       NestedListView list = (NestedListView)findViewById(android.R.id.list); 
       list.setVisibility(View.VISIBLE); 
       CustomList adapter = new CustomList(MainActivity.this, myRssFeed.getList()); 
       adapter.addAll(); 
       list.setAdapter(adapter); 

      } else 
       Toast.makeText(MainActivity.this, "Error", 
        Toast.LENGTH_LONG).show(); 
     } 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 
} 

的RSSFeed

public class RSSFeed { 
    private String title = null; 
    private String description = null; 
    private String link = null; 
    private String pubdate = null; 
    private String image = null; 
    private String enclosure = null; 
    private String author = null; 
    private List<RSSItem> itemList; 

    RSSFeed(){ 
     itemList = new Vector<RSSItem>(0); 
    } 

    void addItem(RSSItem item){ 
     itemList.add(item); 
    } 
    RSSItem getItem(int location){ 
     return itemList.get(location); 
    } 
    List<RSSItem> getList(){ 
     return itemList; 
    } 

} 

的RSSItem

public class RSSItem { 

    private String title = null; 
    private String description = null; 
    private String link = null; 
    private String pubdate = null; 
    private String image = null; 
    private String enclosure = null; 
    private String author = null; 
} 

CustomList

public class CustomList extends ArrayAdapter<RSSItem> { 

    private static Activity context = null; 
    private final List<RSSItem> web; 

    public CustomList(Activity context, List<RSSItem> web) { 
     super(context, R.layout.new_listview, web); 
     CustomList.context = context; 
     this.web = web; 
    } 

    @SuppressLint("SetTextI18n") 
    @Override 
    public View getView(final int position, View view, ViewGroup parent) { 
     LayoutInflater inflater = context.getLayoutInflater(); 
     @SuppressLint({"ViewHolder", "InflateParams"}) final View rowView = inflater.inflate(R.layout.new_listview, null, true); 
     ImageView imageView = (ImageView)rowView.findViewById(R.id.image); 
      Picasso.with(context).load(web.get(position).getImage()).into(imageView); 

     TextView textView = (TextView)rowView.findViewById(R.id.title); 
     textView.setText(Html.fromHtml(web.get(position).getTitle())); 

     TextView textView1 = (TextView)rowView.findViewById(R.id.description); 
     textView1.setText(web.get(position).getDescription()); 

     TextView textView2 = (TextView)rowView.findViewById(R.id.pubdate); 
     textView2.setText(pubdate); 

     return rowView; 

    } 

} 

RSSHandler

public class RSSHandler extends DefaultHandler { 

    final int state_unknown = 0; 
    final int state_title = 1; 
    final int state_description = 2; 
    final int state_link = 3; 
    final int state_pubdate = 4; 
    final int state_enclosure = 6; 
    final int state_image = 5; 
    final int state_author = 7; 
    int currentState = state_unknown; 
    String url; 

    RSSFeed feed; 
    RSSItem item; 

    boolean itemFound = false; 

    RSSHandler(){ 
    } 

    RSSFeed getFeed(){ 
     return feed; 
    } 

    @Override 
    public void startDocument() throws SAXException { 
     // TODO Auto-generated method stub 
     feed = new RSSFeed(); 
     item = new RSSItem(); 

    } 

    @Override 
    public void startElement(String uri, String localName, String qName, 
         Attributes attributes) throws SAXException { 

     // TODO Auto-generated method stub 

     if (localName.equalsIgnoreCase("item")){ 
      itemFound = true; 
      item = new RSSItem(); 
      currentState = state_unknown; 
     } 
     else if (localName.equals("enclosure")) { 
      url = attributes.getValue("url"); 
      currentState = state_image; 
     } 
     else if (localName.equalsIgnoreCase("title")){ 
      currentState = state_title; 
     } 
     else if (localName.equalsIgnoreCase("description")){ 
      currentState = state_description; 
     } 
     else if (localName.equalsIgnoreCase("link")){ 
      currentState = state_link; 
     } 
     else if (localName.equalsIgnoreCase("pubdate")){ 
      currentState = state_pubdate; 
     } 
     else if (localName.equalsIgnoreCase("author")){ 
      currentState = state_author; 
     } 
     else{ 
      currentState = state_unknown; 
     } 

    } 

    @Override 
    public void endElement(String uri, String localName, String qName) 
      throws SAXException { 
     // TODO Auto-generated method stub 
     if (localName.equalsIgnoreCase("item")){ 
      feed.addItem(item); 
     } 
    } 

    @Override 
    public void characters(char[] ch, int start, int length) 
     throws SAXException { 
     // TODO Auto-generated method stub 

     String strCharacters = new String(ch,start,length); 

     if (itemFound){ 
      // "item" tag found, it's item's parameter 
      switch(currentState){ 
       case state_enclosure: 
        item.setEnclosure(strCharacters); 
        break; 
       case state_title: 
        item.setTitle(strCharacters); 
        break; 
       case state_image: 
        item.setImage(url); 
        break; 
       case state_description: 
        item.setDescription(strCharacters); 
        break; 
       case state_link: 
        item.setLink(strCharacters); 
        break; 
       case state_pubdate: 
        item.setPubdate(strCharacters); 
        break; 
       case state_author: 
        item.setAuthor(strCharacters); 
        break; 
       default: 
        break; 
      } 
     } 
     else{ 
      // not "item" tag found, it's feed's parameter 
      switch(currentState){ 
       case state_enclosure: 
        feed.setEnclosure(strCharacters); 
        break; 
       case state_title: 
        feed.setTitle(strCharacters); 
        break; 
       case state_image: 
        feed.setImage(url); 
        break; 
       case state_description: 
        feed.setDescription(strCharacters); 
        break; 
       case state_link: 
        feed.setLink(strCharacters); 
        break; 
       case state_pubdate: 
        feed.setPubdate(strCharacters); 
        break; 
       case state_author: 
        feed.setAuthor(strCharacters); 
        break; 
       default: 
        break; 
      } 
     } 

     currentState = state_unknown; 
    } 

Answer 1

溶液需要多於一個變化。你需要做的第一件事就是讓每個完成的新聞任務將其數據添加到一個大列表中。然後可以對該列表進行排序，這需要Comparator。

您還需要一個名稱列表，以顯示在圖像中稱爲Source n的佔位符中，最後爲了比較它們，您需要將日期解析爲實際日期。

public class MainActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener { 

    private List<RSSItem> totalRssFeed = new ArrayList<>(); 
    String[] urlFeed = {"MyURL", "MyUrl2", "MyUrl3"}; 
    String[] names = {"Name", "Name2", "Name3"} 
    private CustomList adapter; 

    @Override 
    public void onCreate(Bundle savedInstanceState, PersistableBundle persistentState) { 
     super.onCreate(savedInstanceState, persistentState); 
     ListView list = (ListView) findViewById(android.R.id.list); 
     adapter = new CustomList(MainActivity.this); 
     list.setAdapter(adapter); 
    } 

    @Override 
    protected void onResume() { 
     // do this here and you dont need to repeat it in refresh and create 
     for (int i = 0; i < urlFeed.length; i++) { 
      News news = new News(i); 
      news.execute(); 
     } 
    } 

    public class CustomList extends ArrayAdapter<RSSItem> { 

     ... 

     public CustomList(Activity context) { //dont start with default data 
      super(context, R.layout.new_listview, null); 
     } 

     ... 

    } 

    private class News extends AsyncTask<Object, Void, Void> { 

     protected int number; 

     public News(int urlNumber) { 
      number = urlNumber; 
     } 

     @Override 
     protected Void doInBackground(Object... arg0) { 
      try { 

       //no need to do the input stuff you were doing before here? 
       URL url = new URL(urlFeed[number]); 
       SAXParserFactory mySAXParserFactory = SAXParserFactory.newInstance(); 
       SAXParser mySAXParser = mySAXParserFactory.newSAXParser(); 
       XMLReader myXMLReader = mySAXParser.getXMLReader(); 
       RSSHandler myRSSHandler = new RSSHandler(names[number]); 
       myXMLReader.setContentHandler(myRSSHandler); 
       InputSource myInputSource = new InputSource(url.openStream()); 
       myXMLReader.parse(myInputSource); 
       totalRssFeed.addAll(myRSSHandler.getFeed()); 
       Collections.sort(totalRssFeed); 

      } catch (ParserConfigurationException | IOException | SAXException e) { /* stuff */ } 
      return null; 
     } 

     @Override 
     protected void onPostExecute(Void result) { 
      super.onPostExecute(result); 
      adapter.clear(); 
      adapter.addAll(totalRssFeed); 
     } 

    } 

    public class RSSItem implements Comparable<RSSItem> { 

     public String tag; 
     public Date pubdate; //just public so i didnt need setters in this example 

     public RSSItem(String defaultTagToUse) { 
      //You should set the default to whatever you want displayed 
      //when the tag for <category> is missing, and just update it normally otherwise 
      tag = defaultTagToUse; 
     } 

     void setPubDate(Date date) { 
      pubdate = date; 
     } 

     ... 

     @Override 
     public int compareTo(@NonNull RSSItem another) { 
      int res; 
      if (pubdate == null) { 
       if (another.pubdate == null) { 
        res = 0; 
       } else { 
        res = -1; 
       } 
      } else { 
       if (another.pubdate == null || pubdate.getTime() > another.pubdate.getTime()) { 
        res = 1; 
       } else { 
        res = -1; 
       } 
      } 
      return res; 
     } 

    } 

    public class RSSHandler extends DefaultHandler { 

     ... 
     List<RSSItem> feed; 
     RSSItem item; 
     String mName; 

     public RssHandler(String name) { 
      mName = name; 
     } 

     List<RSSItem> getFeed() { 
      return feed; 
     } 

     @Override 
     public void startDocument() throws SAXException { 
      feed = new ArrayList<>(); 
     } 

     @Override 
     public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { 
      if (localName.equalsIgnoreCase("item")) { 
       itemFound = true; 
       item = new RSSItem(name); 
       currentState = state_unknown; 
      } else ... 
     } 

     @Override 
     public void endElement(String uri, String localName, String qName) throws SAXException { 
      if (localName.equalsIgnoreCase("item")) { 
       feed.add(item); 
      } 
     } 

     @Override 
     public void characters(char[] ch, int start, int length) throws SAXException { 
      ... 
      case state_pubdate: 
       SimpleDateFormat formatter = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z"); //make sure you match the format from your XML 
       item.setPubdate(formatter.parse(stringCharacters)); 
      break; 
      ... 
     } 
    } 
} 

所有...的僅僅指剛離開意味着一切，因爲它是在那些地方