ANDROID:解析XML

Question

我不是开发人员,我只是涉猎编程.我从未理解的一个领域是XML解析.可悲的是,对于我最新的"项目",我需要为Android应用程序做这件事.它是我为工作做的原型.

我有这个XML(一个模拟文件):

<feed version="201010011221" > 
  <period from="2010-10-01T10:08:34Z" to="2010-10-01T10:08:34Z"> 
    <lines> 
      <line id="SKI" name="Ski" shortname="ski" status="1 calls queued"> 
        <calls> 
          <call id="6584" created="2010-10-01T11:22:42Z">
            <booking>1275243</booking>
          </call> 
        </calls> 
      </line> 
      <line id="CRU" name="Cruise" shortname="cruise" status="0 calls queued"> 
        <calls /> 
      </line> 
      <line id="VIL" name="Villas" shortname="villas" status="2 calls queued"> 
        <calls> 
          <call id="25878" created="2010-10-01T10:22:42Z">
            <booking>1077244</booking>
          </call> 
          <call id="25878" created="2010-10-01T10:22:42Z">
            <booking>1077244</booking>
          </call> 
        </calls> 
      </line>
    </lines>
  </period> 
</feed>

我有一些代码,让我得到每个的NodeList:

inputStream = OpenHttpConnection(URL);
Document document = null;
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder;
documentBuilder = documentBuilderFactory.newDocumentBuilder();
document = documentBuilder.parse(inputStream);
document.getDocumentElement().normalize();
NodeList lineNodes = document.getElementsByTagName("line");

我不知道下一步该做什么.我的代码似乎很长.我用Google搜索了更好的方法,但是我找到了一些更清晰的代码,我无法开始工作.

有没有好的Android XML教程？或者有人可以帮助我使用此代码？

我需要将每个进入HashMap,其中String是ID.

Line是显示的所有信息的类.

谢谢尼尔

Answer 1

我宁愿不使用DOM,因为它有更大的内存占用.使用DOM,整个XML结构首先加载到内存中,然后进行处理.这可能不是移动开发的最佳解决方案.

使用Android附带的SAX解析器.这是一种事件驱动的方法.每个起始标记,标记之间的内容和结束标记在发生时触发事件.实际上它可以处理更多事件,但这些事件是最常用的事件.这意味着SAX解析器逐个处理每一行,而不首先将整个XML结构加载到内存中.

我明天会为你的特定问题发布一个例子.

编辑:这是承诺的内容处理程序示例.

import java.util.HashMap;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;

public class MyContentHandler implements ContentHandler {

    private HashMap<String, Object> feed;
    private HashMap<String, Object> peroidContent;
    private HashMap<String, Object> callContent;
    private HashMap<String, Object> callsMap;
    private HashMap<String, Object> lineContent;
    private HashMap<String, Object> linesMap;

    private String text;
    private String callId;
    private String lineId;

    @Override
    public void startDocument() throws SAXException {
        /* You can perform some action in this method
         * for example to reset some sort of Collection
         * or any other variable you want. It gets called
         * every time a document starts. */
        feed = new HashMap<String, Object>();
    }

    @Override
    public void startElement(String uri, String localName, String qName,
            Attributes atts) throws SAXException {
        // Gets called every time an opening tag is encountered.
        if(localName.equalsIgnoreCase("FEED")) {
            /* We've found a "feed" opening tag so we capture its
             * version attribute and put it into our HashMap.*/
            feed.put("Version", atts.getValue("version"));
        } else if(localName.equalsIgnoreCase("PEROID")) {
            peroidContent = new HashMap<String, Object>();
            peroidContent.put("From", atts.getValue("from"));
            peroidContent.put("to", atts.getValue("to"));
        } else if(localName.equalsIgnoreCase("LINE")) {
            linesMap = new HashMap<String, Object>();
        } else if(localName.equalsIgnoreCase("LINE")) {
            lineContent = new HashMap<String, Object>();
            lineId = atts.getValue("id");
            lineContent.put("name", atts.getValue("name"));
            lineContent.put("shortname", atts.getValue("shortname"));
            lineContent.put("status", atts.getValue("status"));
        } else if(localName.equalsIgnoreCase("CALLS")) {
            callsMap = new HashMap<String, Object>();
        } else if(localName.equalsIgnoreCase("CALL")) {
            callContent = new HashMap<String, Object>();
            callId = atts.getValue("Id");
            callContent.put("created", atts.getValue("created"));
        }
    }

    @Override
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        /* Gets called every time in between an opening tag and
         * a closing tag if characters are encountered. */
        text = new String(ch, start, length);
    }

    @Override
    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        // Gets called every time a closing tag is encountered.
        if(localName.equalsIgnoreCase("FEED")) {
            feed.put("Peroid", peroidContent);
        } else if(localName.equalsIgnoreCase("PEROID")) {
            peroidContent.put("Lines", linesMap);
        } else if(localName.equalsIgnoreCase("LINES")) {
            linesMap.put(lineId, lineContent);
        } else if(localName.equalsIgnoreCase("LINE")) {
            lineContent.put("Calls", callsMap);
        } else if(localName.equalsIgnoreCase("CALLS")) {
            callsMap.put(callId, callContent);
        } else if(localName.equalsIgnoreCase("BOOKING")) {
            callContent.put("Booking", text.toString());
        }
    }

    @Override
    public void endDocument() throws SAXException {
        /* You can perform some action in this method
         * for example to reset some sort of Collection
         * or any other variable you want. It gets called
         * every time a document end is reached. */
        SAXParsingFun.setHashMap(feed);
    }

    @Override
    public void endPrefixMapping(String prefix) throws SAXException {
        // TODO Auto-generated method stub
    }

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

    @Override
    public void processingInstruction(String target, String data)
            throws SAXException {
        // TODO Auto-generated method stub
    }

    @Override
    public void setDocumentLocator(Locator locator) {
        // TODO Auto-generated method stub
    }

    @Override
    public void skippedEntity(String name) throws SAXException {
        // TODO Auto-generated method stub
    }

    @Override
    public void startPrefixMapping(String prefix, String uri)
            throws SAXException {
        // TODO Auto-generated method stub
    }
}

StackOverflow上有很多关于如何解析XML文件的解释,我已经把它留下来了,只是向你展示了更有趣的部分; 内容处理程序.

现在,大多数有趣的部分都会被评论,以便您了解我正在尝试做什么.

我已经实现了界面,ContentHandler只是为了向您展示有更多可用的方法,也许您将来需要其中一种方法.但是,您可以从类扩展DefaultHandler而只是覆盖所需的方法.您所做的只是检查某些标签的出现,然后触发某些事件.如果要保留XML文件中元素的顺序,则只需使用a LinkedHashMap而不是a HashMap.

我希望它有所帮助.