Android:Sax 解析为 ListView

Question

首先，我是 Android 和 Java 的新手。我一直在尝试将“简单”的 Rss 阅读器添加到我的应用程序中。我想要它做的就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 ListView 中，当单击列表项目时它将打开浏览器以显示包含该文章的网页。够简单吧？很遗憾地说，这让我困惑了几天。

我已经阅读了一些教程/示例，我正在尝试修改以适合我的目的的代码如下所示:
主要 Activity

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);
    }
}

示例处理器

   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));
}
}
}

解析示例数据集

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;
    }
}

当然，这只会返回提要中的最后一个条目。它正在正确解析，因为我可以获得要单独显示的每个元素。我对如何实现 listveiw 一无所知。

提前致谢

Answer 1

让我们一步一步来，希望我们能实现您想要做的事情。我已经包含了您需要了解的 API 文档的相关链接。

• 对于 ListView，DOM 可能是一个更简单的选择，因为 ListView 在一个列表上运行，该列表可以很好地与结构化列表一起工作。对于刚接触 Android 和 Java 的人来说，它也更容易学习。看这个IBM tutorial for XML在“提要解析器的基于 DOM 的实现”部分。以下是示例中您应该注意的代码部分

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

• 此时您拥有了 ListView 的数据. ListView 通过使用 Adapter 来工作。适配器负责A。设置初始数据和 b。显示每一行的外观。因此，此类对于使 ListView 正常工作很重要
• 现在您要创建自己的 BaseAdapter 扩展这将采用您之前获得的根元素。我在这里提供了一个骨架类:

<p></p>

<pre><code>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;
    }
}
</code></pre>

<p></p>

• 如果你对Element不熟悉，建议你看看下面的Element API Documentation .您需要在上面的 getItem() 函数中正确识别 child
• 现在您已准备好实现 getView() 方法。在这里你基本上会做以下步骤
  • 使用您已实现的 getItem() 访问您想要的子节点
  • 为每一行创建一个 XML 布局并在此处扩充它们。如果您不熟悉 Android View，请查看 View API Documentation因为这是一件重要的事情要知道
  • 从子节点中提取数据并将其设置到您对应的View元素
• 接下来，您需要设置 OnItemClickListener在你的 ListView 上。在监听器中，您可能希望使用 getItem()(此方法对您至关重要)再次获取 XML 并获取链接。
• 最后，在onClick() 的实现中，您想使用WebView。并加载 URL

这应该足以让您实现您想要的。如果步骤不清楚，我会进一步澄清。希望这会有所帮助。