java - java中的XML文档遍历器

Question

每个人都知道我们可以使用 DocumentTraversal 的 NodeIterator 遍历整个 xml 文档。我的应用程序需要一些额外的工作，因此我决定在 java Stack<> 的支持下编写自己的 XML 遍历器。

这是我的代码(我不擅长编码，因此代码和逻辑可能看起来很困惑)。

public class test
{
    private static Stack<Node> gStack = new Stack<Node>();

    public static void main(String[] args) throws XPathExpressionException
    {
        String str =
            "<section>"
                + "<paragraph>This example combines regular wysiwyg editing of a document with very controlled editing of semantic rich content. The main content can be"
                + "edited like you would in a normal word processor. Though the difference is that the content remains schema valid XML because Xopus will not allow you to perform actions"
                + "on the document that would render it invalid.</paragraph>"
                + "<paragraph>The table is an example of controlled style. The style of the table is controlled by three attributes:</paragraph>"
                + "<unorderedlist>"
                + "<item><paragraph><emphasis>alternaterowcolor</emphasis>, do all rows have the same color, or should the background color alternate?</paragraph></item>"
                + "<item><paragraph><emphasis>border</emphasis>, a limited choice of border styles.</paragraph></item>"
                + "<item><paragraph><emphasis>color</emphasis>, a limited choice of colors.</paragraph></item>"
                + "</unorderedlist>"
                + "<paragraph>You have quite some freedom to style the table, but you can't break the predefined style.</paragraph>"
                + "</section>";

        Document domDoc = null;
        try
        {
            DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
            ByteArrayInputStream bis = new ByteArrayInputStream(str.getBytes());
            domDoc = docBuilder.parse(bis);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

        Element root = null;
        NodeList list = domDoc.getChildNodes();
        for (int i = 0; i < list.getLength(); i++)
        {
            if (list.item(i) instanceof Element)
            {
                root = (Element) list.item(i);
                break;
            }
        }

        NodeList nlist = root.getChildNodes();

        System.out.println("root = " + root.getNodeName() + "  child count = " + nlist.getLength());
        domTraversor(root);
    }

    private static void domTraversor(Node node)
    {
        if (node.getNodeName().equals("#text"))
        {
            System.out.println("textElem = " + node.getTextContent());
            if (node.getNextSibling() != null)
            {
                gStack.push(node.getNextSibling());
                domTraversor(node.getNextSibling());
            }
            else
            {
                if (node.getParentNode().getNextSibling() != null)
                    domTraversor(node.getParentNode().getNextSibling());
            }
        }
        else
        {
            if (node.getChildNodes().getLength() > 1)
            {
                gStack.push(node);
                Node n = node.getFirstChild();
                if (n.getNodeName().equals("#text"))
                {
                    System.out.println("textElem = " + n.getTextContent());
                    if (n.getNextSibling() != null)
                    {
                        gStack.push(n.getNextSibling());
                        domTraversor(n.getNextSibling());
                    }
                }
                else
                {
                    gStack.push(n);
                    domTraversor(n);
                }
            }
            else if (node.getChildNodes().getLength() == 1)
            {
                Node fnode = node.getFirstChild();
                if (fnode.getChildNodes().getLength() > 1)
                {
                    gStack.push(fnode);
                    domTraversor(fnode);
                }
                else
                {
                    if (!fnode.getNodeName().equals("#text"))
                    {
                        gStack.push(fnode);
                        domTraversor(fnode);
                    }
                    else
                    {
                        System.out.println("textElem = " + fnode.getTextContent());
                        if (fnode.getNodeName().equals("#text"))
                        {
                            if (node.getNextSibling() != null)
                            {
                                gStack.push(node.getNextSibling());
                                domTraversor(node.getNextSibling());
                            }
                            else
                            {
                                if (!gStack.empty())
                                {
                                    Node sibPn = gStack.pop();
                                    if (sibPn.getNextSibling() == null)
                                    {
                                        sibPn = gStack.pop();
                                    }
                                    domTraversor(sibPn.getNextSibling());
                                }
                            }
                        }
                        else
                        {
                            if (fnode.getNextSibling() != null)
                            {
                                domTraversor(fnode.getNextSibling());
                            }
                            else
                            {
                                if (!gStack.empty())
                                {
                                    Node sibPn = gStack.pop().getNextSibling();
                                    domTraversor(sibPn);
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

它可以很好地处理某些 xml 文档，但不能处理具有类似标签的文档。

<unorderedlist>
    <item>
        <paragraph>
            <emphasis>alternaterowcolor</emphasis>
            , do all rows have the same color, or should the background
            color
            alternate?
        </paragraph>
    </item>
    <item>
        <paragraph>
            <emphasis>border</emphasis>
            , a limited choice of border styles.
        </paragraph>
    </item>
    <item>
        <paragraph>
            <emphasis>color</emphasis>
            , a limited choice of colors.
        </paragraph>
    </item>
</unorderedlist>

这里是如果任何元素有超过三个嵌套子元素的情况，我的代码就会停止并且不再继续。

是否有更好的实现，请提出。

Answer 1

试试这个方法

Element e;
NodeList n;
Document doc=StudyParser.XMLfromString(xmlString);
String starttag=doc.getFirstChild().getNodeName();
   Log.e("start",starttag );
   n=doc.getElementsByTagName(starttag);
   for(int i=0;i<n.getLength();i++){
       e=(Element)n.item(i);
       NodeList np = e.getElementsByTagName("item");
       for(int j=0;j<np.getLength();j++){
           e=(Element)n.item(i);
           try{
           String para=StudyParser.getValue(e, "paragraph");
           Log.e("paravalue",para);
           String emp=StudyParser.getValue(e, "emphasis");       
           Log.e("empval",emp);
           }catch(Exception e){
               e.printStackTrace();
           }
       }
   }

StudyParser 类

    import java.io.BufferedInputStream;
    import java.io.ByteArrayOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.io.StringReader;
    import java.io.UnsupportedEncodingException;
    import java.net.MalformedURLException;

    import javax.xml.parsers.DocumentBuilder;
    import javax.xml.parsers.DocumentBuilderFactory;
    import javax.xml.parsers.ParserConfigurationException;

    import org.apache.http.HttpEntity;
    import org.apache.http.HttpResponse;
    import org.apache.http.client.methods.HttpPost;
    import org.apache.http.impl.client.DefaultHttpClient;
    import org.apache.http.util.EntityUtils;
    import org.w3c.dom.Document;
    import org.w3c.dom.Element;
    import org.w3c.dom.Node;
    import org.w3c.dom.NodeList;
    import org.xml.sax.InputSource;
    import org.xml.sax.SAXException;



    public class StudyParser {
    public StudyParser() {

    }

public final static Document XMLfromString(String xml){
     Document doc = null;

        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            try {

          DocumentBuilder db = dbf.newDocumentBuilder();

          InputSource is = new InputSource();
              is.setCharacterStream(new StringReader(xml));
              doc = db.parse(is); 

        } catch (ParserConfigurationException e) {
          System.out.println("XML parse error: " + e.getMessage());
          return null;
        } catch (SAXException e) {
          System.out.println("Wrong XML file structure: " + e.getMessage());
                return null;
        } catch (IOException e) {
          System.out.println("I/O exeption: " + e.getMessage());
          return null;
        }

            return doc;

  }
public static String getXMLstring(String xml){   
      String line = null;

      try {

        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(xml);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();
        line = EntityUtils.toString(httpEntity);

      } catch (UnsupportedEncodingException e) {
        line = "<results status=\"error\"><msg>Can't connect to server</msg></results>";
      } catch (MalformedURLException e) {
        line = "<results status=\"error\"><msg>Can't connect to server</msg></results>";
      } catch (IOException e) {
        line = "<results status=\"error\"><msg>Can't connect to server</msg></results>";
      }

      return line;

  }
public static String getXML(InputStream is)throws IOException {

    BufferedInputStream bis = new BufferedInputStream(is);
    ByteArrayOutputStream buf = new ByteArrayOutputStream();
    int result = bis.read();
    while(result != -1) {
      byte b = (byte)result;
      buf.write(b);
      result = bis.read();
    }        
    return buf.toString();
}
public final static String getElementValue( Node elem ) {
       Node kid;
       if( elem != null){
           if (elem.hasChildNodes()){
               for( kid = elem.getFirstChild(); kid != null; kid = kid.getNextSibling() ){
                   if( kid.getNodeType() == Node.TEXT_NODE  ){
                       return kid.getNodeValue();
                   }

               }
           }
       }
       return "";
   }
 public static int numResults(Document doc){    
        Node results = doc.getDocumentElement();
        int res = -1;

        try{
          res = Integer.valueOf(results.getAttributes().getNamedItem("Categories").getNodeValue());
        }catch(Exception e ){
          res = -1;
        }

        return res;
      }

      public static String getValue(Element item, String str) {    
        NodeList n = item.getElementsByTagName(str);    
        return StudyParser.getElementValue(n.item(0));
      }


}

只是动态 xml 的普通演示，我假设了相同的 xml，但不使用 getElementByTagName 有许多属性，您可以检查 accodringlly 看到

   doc = StudyParser.XMLfromString(xml);
   String starttag=doc.getFirstChild().getNodeName();
   Log.e("start",starttag );
   n=doc.getElementsByTagName(starttag);
   for(int i=0;i<n.getLength();i++){
       e=(Element)n.item(i);
           try{
             Log.e("1234",""+ e.getTextContent());

           }catch(Exception e){
               e.printStackTrace();
           }

   }