Android：Sax解析为列表视图

Question

首先，我是Android和Java的新手。我一直在试图添加一个“简单”Rss阅读器到我的应用程序。我希望它做的是解析来自特定站点的RSS提要，并获取标题和发布日期，并将这些项目放入列表视图中，当单击列表项时，将打开浏览器以显示包含该文章的网页。够简单吗？我很伤心地说，现在我已经陷入了几天的困境。

我读过一些教程/例子，我试图修改，以适应我的目的看起来像代码：
主要活动

public class News extends Activity { 

    private final String MY_DEBUG_TAG = "Some NEWS"; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle icicle) { 
      super.onCreate(icicle); 

      /* Create a new TextView to display the parsingresult later. */ 
      TextView tv = new TextView(this); 
      try { 
        /* Create a URL we want to load some xml-data from. */ 
        URL url = new URL("http://www.some.com/feed/"); 

        /* Get a SAXParser from the SAXPArserFactory. */ 
        SAXParserFactory spf = SAXParserFactory.newInstance(); 
        SAXParser sp = spf.newSAXParser(); 

        /* Get the XMLReader of the SAXParser we created. */ 
        XMLReader xr = sp.getXMLReader(); 
        /* Create a new ContentHandler and apply it to the XML-Reader*/ 
        ExampleHandler myExampleHandler = new ExampleHandler(); 
        xr.setContentHandler(myExampleHandler); 

        /* Parse the xml-data from our URL. */ 
        xr.parse(new InputSource(url.openStream())); 
        /* Parsing has finished. */ 

        /* Our ExampleHandler now provides the parsed data to us. */ 
        ParsedExampleDataSet parsedExampleDataSet = 
                    myExampleHandler.getParsedData(); 

        /* Set the result to be displayed in our GUI. */ 
        tv.setText(parsedExampleDataSet.toTitle()); 

      } catch (Exception e) { 
        /* Display any Error to the GUI. */ 
        tv.setText("Error: " + e.getMessage()); 
        Log.e(MY_DEBUG_TAG, "NewsQueryError", e); 
      } 
      /* Display the TextView. */ 
      this.setContentView(tv); 
    } 
} 

ExampleHandler

public class ExampleHandler extends DefaultHandler{ 

    // =========================================================== 
    // Fields 
    // =========================================================== 

    private boolean in_entry = false; 
    private boolean in_id = false; 
    private boolean in_title = false; 
    private boolean in_updated = false; 
    private boolean in_summary = false; 
    private boolean in_link = false; 

    private ParsedExampleDataSet myParsedExampleDataSet = new ParsedExampleDataSet(); 




    // =========================================================== 
    // Getter & Setter 
    // =========================================================== 

    public ParsedExampleDataSet getParsedData() { 
     return this.myParsedExampleDataSet; 
    } 

    // =========================================================== 
    // Methods 
    // =========================================================== 
    @Override 
    public void startDocument() throws SAXException { 
     this.myParsedExampleDataSet = new ParsedExampleDataSet(); 
    } 

    @Override 
    public void endDocument() throws SAXException { 
      // Nothing to do 
    } 

    /** Gets be called on opening tags like: 
    * <tag> 
    * Can provide attribute(s), when xml was like: 
    * <tag attribute="attributeValue">*/ 
    @Override 
    public void startElement(String namespaceURI, String localName, 
        String qName, Attributes atts) throws SAXException { 
      if (localName.equals("entry")) {      
        this.in_entry = true; 
      }else if (localName.equals("id")) {     
        this.in_id = true; 
      }else if (localName.equals("title")) { 
        this.in_title = true; 
      }else if (localName.equals("updated")){ 
        this.in_updated = true; 
      }else if (localName.equals("summary")) { 
        this.in_summary = true; 
      }else if (localName.equals("link")) { 
        this.in_link = true; 
      } 
    } 

    /** Gets be called on closing tags like: 
    * </tag> */ 
    @Override 
    public void endElement(String namespaceURI, String localName, String qName) 
        throws SAXException { 
      if (localName.equals("entry")) { 
        this.in_entry = false; 
      }else if (localName.equals("id")) { 
        this.in_id = false; 
      }else if (localName.equals("title")) { 
        this.in_title = false; 
      }else if (localName.equals("updated")) { 
        this.in_updated = false; 
      }else if (localName.equals("summary")) { 
        this.in_summary = false; 
      }else if (localName.equals("link")) { 
        this.in_link = false; 
      } 
    } 

    /** Gets be called on the following structure: 
    * <tag>characters</tag> */ 
    public void characters(char ch[], int start, int length) { 
     if(this.in_title){ 
     myParsedExampleDataSet.setextractedTitle(new String(ch, start, length)); 
} 
} 
} 

ParsedExampleDataSet

public class ParsedExampleDataSet { 
    private String extractedId = null; 
    private String extractedTitle = null; 
    private String extractedUpdated = null; 
    private String extractedSummary = null; 
    private String extractedImage = null; 
    private int extractedInt = 0; 

    public String getextractedId() { 
      return extractedId; 
    } 
    public void setextractedId(String extractedId) { 
      this.extractedId = extractedId; 
    } 

    public String getextractedTitle() { 
     return extractedTitle; 
    } 
    public void setextractedTitle(String extractedTitle) { 
     this.extractedTitle = extractedTitle; 
    } 
    public String getextractedUpdated() { 
     return extractedUpdated; 
    } 
    public void setextractedUpdated(String extractedUpdated) { 
     this.extractedUpdated = extractedUpdated; 
    } 

    public String getextractedSummary() { 
     return extractedSummary; 
    } 
    public void setextractedSummary(String extractedSummary) { 
     this.extractedSummary = extractedSummary; 
    } 



    public String toId(){ 
      return this.extractedId; 
    } 

    public String toTitle(){ 
     return this.extractedTitle; 
    } 

    public String toUpdated(){ 
     return this.extractedUpdated; 
    } 

    public String toSummary(){ 
     return this.extractedSummary; 
    } 
} 

现在当然这个w生病只是返回Feed中的最后一个条目。它正在解析正确，因为我可以获得我想单独显示的每个元素。对于如何实施清单，我无能为力。

在此先感谢

Answer 1

让我们一步一步来，希望我们可以达到你想要做什么。我已经包含了您需要了解的API文档的相关链接。

• 对于ListView来说，DOM可能是一个更简单的选择，因为ListView在列表上运行，可以很好地处理结构化列表。对于刚接触Android和Java的人来说，学习也更容易。请参阅IBM tutorial for XML关于“基于DOM的feed解析器的实现”部分。下面是你应该关心代码的例子

    DocumentBuilder builder = factory.newDocumentBuilder(); 
    Document dom = builder.parse(this.getInputStream()); 
    Element root = dom.getDocumentElement(); 

• 部分在这一点上，你有你的ListView数据。 ListView通过使用适配器来工作。适配器是一个负责 a。设置初始数据和b。显示每行应该如何。因此，这个类对于使ListView工作很重要
• 现在，您将创建自己的扩展名为BaseAdapter，它将采用之前获得的根元素。我在这里提供了一个框架类：

 

import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 

public class RSSAdapter extends BaseAdapter { 
    Element rootElement; 

    public RSSAdapter(Element rootElement) { 
     this.rootElement = rootElement; 
    } 

    public int getCount() { 
     // get the count of children of the root element 
     return 0; 
    } 

    public Object getItem(int position) { 
     // get the child identified by the position, 
     // this is the important part where you  
     // want to get the right child representing the RSS data that you want to get 
     return null; 
    } 

    public long getItemId(int position) { 
     return position; 
    } 

    public View getView(int position, View convertView, ViewGroup parent) { 
     // implement your view here.... 
     return null; 
    } 
} 
 

• 如果你不熟悉的元素，我建议你看看下面的Element API Documentation。您需要正确识别上面的getItem（）函数中的孩子
• 现在您已准备好实施getView（）方法。在这里，您将基本上完成下面的操作
  • 可以访问您要使用getItem（）时，你已经实现
  • 创建每一行的XML布局，在这里夸大他们的子节点。如果你不熟悉Android设备上查看，看看View API Documentation，因为这是要知道
  • 从子节点提取数据，并将它设置为您相应的视图元素
• 下一个重要的事情，你需要设置在您的ListView上添加OnItemClickListener。在监听器中，您希望使用getItem（）再次获取XML（此方法对您至关重要）并获取链接。
• 最后，在的onClick（）的实施，要使用WebView并加载URL

这应该足以让你实现你想要的。如果步骤不明确，我会进一步澄清。希望这可以帮助。