Java 为什么在解析RSS提要时必须两次初始化对象

在MainActivity.java中，我编写了解析代码，如

public void parser() {
    try {
        /****** Creating a new instance of the SAX parser ****************/
        SAXParserFactory saxPF = SAXParserFactory.newInstance();
        SAXParser saxParser = saxPF.newSAXParser();
        XMLReader xmlReader = saxParser.getXMLReader();

        URL url = new URL("http://ibnlive.in.com/ibnrss/rss/world/world.xml");

        myXMLHandler = new FeedsXMLHandler();
        xmlReader.setContentHandler(myXMLHandler);
        xmlReader.parse(new InputSource(url.openStream()));     
    } catch (Exception e) {
        e.printStackTrace();
    }
    feedsData = myXMLHandler.getXMLData();
}

我正在使用IBN Live的rss源

我的处理程序类XMLHandler.java如下所示：

@Override
public void startElement(String uri, String localName, String qName,
                     Attributes attributes) throws SAXException {
    elementValue = "";
    elementOn = true;

    if (localName.equalsIgnoreCase("rss")) {
        dataArray = new ArrayList<FeedsItems>();
        data = new FeedsItems();
        Log.v("Item", "I am in rss block");
    }

    if (localName.equalsIgnoreCase("channel")) {
       Log.v("Item", "I am in channel block");
    }

    if (localName.equalsIgnoreCase("item")) {
       data = new FeedsItems();
       Log.v("Item", "I am in item block");
    }

    if (localName.equalsIgnoreCase("description")) {
       bufferDesc = new StringBuffer();
       elementOn = true;
    }

    if (localName.equalsIgnoreCase("title")) {
       bufferTitle = new StringBuffer();
       elementOn = true;
    }

    if (localName.equalsIgnoreCase("link")) {
            bufferLink = new StringBuffer();
            elementOn = true;
    }
}

/*********** Method will be called when the tags of the XML end **************/
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
    elementOn = false;

    /*** Sets the values after retrieving the values from the XML tags ******/
    if (localName.equalsIgnoreCase("title")) {
        elementOn = false;

        data.setTitle(bufferTitle.toString());
        bufferTitle.delete(0, bufferTitle.length());
        Log.v("title", data.getTitle());
    }
    else if (localName.equalsIgnoreCase("link")) {
        elementOn = false;

        data.setFeedsUrl(bufferLink.toString());
        bufferLink.delete(0, bufferLink.length());
    }
    else if (localName.equalsIgnoreCase("description")) {
        elementOn = false;

        data.setDescription(bufferDesc.toString());
        bufferDesc.delete(0, bufferDesc.length());
    } else if (localName.equalsIgnoreCase("item")) {
        dataArray.add(data);
    }
}

public void characters(char[] ch, int start, int length) throws SAXException {
    if (elementOn) {
        if (bufferDesc != null) {
            bufferDesc.append(new String(ch, start, length).trim());
        }

        if (bufferTitle != null) {
            bufferTitle.append(new String(ch, start, length).trim());
        }

        if (bufferLink != null) {
            bufferLink.append(new String(ch, start, length).trim());
        }

    } else {
        elementValue = new String(ch, start, length);
    }
}

试试这个

@Override
public void startElement(String uri, String localName, String qName,
                     Attributes attributes) throws SAXException {
    elementValue = "";
    elementOn = true;

    if (localName.equalsIgnoreCase("rss")) {
        dataArray = new ArrayList<FeedsItems>();
        data = new FeedsItems();
        bufferLink = new StringBuffer();
        bufferDesc = new StringBuffer();
        bufferTitle = new StringBuffer();
        Log.v("Item", "I am in rss block");
    }    
    else if (localName.equalsIgnoreCase("channel")) {
       Log.v("Item", "I am in channel block");
    }    
    else if (localName.equalsIgnoreCase("item")) {           
       Log.v("Item", "I am in item block");
    }    
    else if (localName.equalsIgnoreCase("description")) {          
       elementOn = true;
    }    
    else if (localName.equalsIgnoreCase("title")) {
       elementOn = true;
    }    
    else if (localName.equalsIgnoreCase("link")) {                
            elementOn = true;
    }
}

@覆盖
public void startElement（字符串uri、字符串localName、字符串qName、，
属性）引发SAX异常{
elementValue=“”；
elementOn=true；
if（localName.equalsIgnoreCase（“rss”））{
dataArray=新的ArrayList（）；
数据=新的FeedsItems（）；
bufferLink=新的StringBuffer（）；
bufferDesc=新的StringBuffer（）；
bufferTitle=新的StringBuffer（）；
Log.v（“项目”，“我在rss块中”）；
}    
else if（localName.equalsIgnoreCase（“通道”））{
Log.v（“项目”，“我在通道区”）；
}    
else if（localName.equalsIgnoreCase（“项”）{
Log.v（“项目”，“我在项目块中”）；
}    
else if（localName.equalsIgnoreCase（“description”）{
elementOn=true；
}    
else if（localName.equalsIgnoreCase（“title”））{
elementOn=true；
}    
else if（localName.equalsIgnoreCase（“link”）{
elementOn=true；
}
}

您必须执行两次，因为

和

（以及

）都使用

标记。如果你不把它实例化

if (localName.equalsIgnoreCase("rss")) {
...
}

当您在第一个

---

您要做的是保留这两个元素，或者删除“rss”的一个元素，并在endElement（）中添加一个检查项，确保标题属于

，而不是任何其他元素。

在

FeedsXMLHandler.java

中的行号83是什么？您可以发布一个示例，说明您试图解析的rss提要是什么样子的吗？也许有些元素您不希望在其中找到它们。@Tamilan:行号83是data.setTitle（bufferTitle.toString（））；（在endElement（…）方法中）@TofferJ：这是rss的urlfeed@user3022836检查我的答案。。

if (localName.equalsIgnoreCase("rss")) {
...
}