Android SAX XML Parser Access Enclosure 标签 URL 属性

Posted 2023-02-24

【中文标题】Android SAX XML Parser Access Enclosure 标签 URL 属性

【英文标题】：Android SAX XML Parser Access Enclosure Tag URL Attribute

【发布时间】：2011-12-18 23:18:15

【问题描述】：

我创建了一个包含详细视图的 XML 解析器。我正在阅读包含附件标签的 RSS 提要。我正在尝试从附件标签中获取视频文件的 URL。

这是附件标签的样子：

<enclosure url="http://video.calvaryccm.com/main/podcastmp4/MB66-03.mp4" type="video/mp4"/>

每次我尝试检索它时，解析器都会返回 null。我该怎么办？

这是显示似乎导致问题的解析器结果的部分：

// TESTING HERE!
String enclosure = b.getString("enclosure");
// What is getting displayed
theTitle = b.getString("title").trim();
theDate = newDateStr;
theStory = b.getString("description") + "\n\nView in full website:\n" + b.getString("link")+ "\n\nDownload teaching:\n" + enclosure;

这是 RSSHandler 类：

public class RSSHandler extends DefaultHandler 


RSSFeed _feed;
RSSItem _item;
String _lastElementName = "";
boolean bFoundChannel = false;
final int RSS_TITLE = 1;
final int RSS_LINK = 2;
final int RSS_DESCRIPTION = 3;
final int RSS_ENCLOSURE = 4;
final int RSS_PUBDATE = 5;

int depth = 0;
int currentstate = 0;
/*
 * Constructor 
 */
RSSHandler()



/*
 * getFeed - this returns the feed when all of the parsing is complete
 */
RSSFeed getFeed()

    return _feed;



public void startDocument() throws SAXException

    // Initialize RSSFeed object - this will hold parsed contents
    _feed = new RSSFeed();
    // Initialize the RSSItem object - we will use this as a crutch to grab the info from the channel
    // because the channel and items have very similar entries..
    _item = new RSSItem();


public void endDocument() throws SAXException


public void startElement(String namespaceURI, String localName,String qName, Attributes atts) throws SAXException

    depth++;
    if (localName.equals("channel"))
    
        currentstate = 0;
        return;
    
    if (localName.equals("image"))
    
        // Record feed data - Temporarily stored it in the item
        _feed.setTitle(_item.getTitle());
        _feed.setPubDate(_item.getPubDate());
    
    if (localName.equals("item"))
    
        // create a new item
        _item = new RSSItem();
        return;
    
    if (localName.equals("title"))
    
        currentstate = RSS_TITLE;
        return;
    
    if (localName.equals("description"))
    
        currentstate = RSS_DESCRIPTION;
        return;
    
    if (localName.equals("link"))
    
        currentstate = RSS_LINK;
        return;
    
    if (localName.equals("enclosure"))
    
        currentstate = RSS_ENCLOSURE;
        return;
    
    if (localName.equals("pubDate"))
    
        currentstate = RSS_PUBDATE;
        return;
    
    // If I don't explicitly handle the element and to make sure I don't wind up erroneously 
    // storing a newline or other fake data into one of our existing elements
    currentstate = 0;


public void endElement(String namespaceURI, String localName, String qName) throws SAXException

    depth--;
    if (localName.equals("item"))
    
        // Add the item to the list!
        _feed.addItem(_item);
        return;
    


public void characters(char ch[], int start, int length)

    String theString = new String(ch,start,length);
    Log.i("Rs-s-reader","characters[" + theString + "]");

    switch (currentstate)
    
        case RSS_TITLE:
            _item.setTitle(theString);
            currentstate = 0;
            break;
        case RSS_LINK:
            _item.setLink(theString);
            currentstate = 0;
            break;
        case RSS_DESCRIPTION:
            _item.setDescription(theString);
            currentstate = 0;
            break;
        case RSS_ENCLOSURE:
            _item.setEnclosure(theString);
            currentstate = 0;
            break;
        case RSS_PUBDATE:
            _item.setPubDate(theString);
            currentstate = 0;
            break;
        default:
            return;
    

这是 RSSFeed 类：

public class RSSFeed 

private String _title = null;
private String _pubdate = null;
private String _enclosure = null;
private int _itemcount = 0;
private List<RSSItem> _itemlist;


RSSFeed()

    _itemlist = new Vector<RSSItem>(0); 

int addItem(RSSItem item)

    _itemlist.add(item);
    _itemcount++;
    return _itemcount;

RSSItem getItem(int location)

    return _itemlist.get(location);

List<RSSItem> getAllItems()

    return _itemlist;

int getItemCount()

    return _itemcount;

void setTitle(String title)

    _title = title;

void setPubDate(String pubdate)

    _pubdate = pubdate;

void setEnclosure(String enclosure)

    _enclosure = enclosure;

String getTitle()

    return _title;

String getPubDate()

    return _pubdate;

String getEnclosure()

    return _enclosure;

这是 RSSItem 类：

public class RSSItem 

    private String _title = null;
    private String _description = null;
    private String _link = null;
    private String _enclosure = null;
    private String _pubdate = null;


RSSItem()


void setTitle(String title)

    _title = title;

void setDescription(String description)

    _description = description;

void setLink(String link)

    _link = link;

void setEnclosure(String enclosure)

    _enclosure = enclosure;

void setPubDate(String pubdate)

    _pubdate = pubdate;

String getTitle()

    return _title;

String getDescription()

    return _description;

String getLink()

    return _link;

String getEnclosure()

    return _enclosure;

String getPubDate()

    return _pubdate;

public String toString()

    // limit how much text we display
    if (_title.length() > 42)
    
        return _title.substring(0, 42) + "...";
    
    return _title;

 

【问题讨论】：

你的b是什么对象？您的所有对象都没有定义 getString(String) 方法。

b 是我用来将数据从一个类传输到另一个类的包的名称 像这样：Bundle b = startingIntent.getBundleExtra("android.intent.extra.INTENT");跨度>

【参考方案1】：

url标签是一个属性，所以当localName是“enclosure”时，你可以在startElement中调用attributes.getValue("url");来访问它。