Android中XML的基本操作（增、删、改、查）

Android中XML的一些操作

解析类：

// 构造方法
  public XMLParser() { 

  } 

  /**
   * 从URL获取XML使HTTP请求
   *
   * @param url
   *      string
   * */
  public String getXmlFromUrl(String url) {
    String xml = null; 

    try {
      // defaultHttpClient
      DefaultHttpClient httpClient = new DefaultHttpClient();
      HttpPost httpPost = new HttpPost(url); 

      HttpResponse httpResponse = httpClient.execute(httpPost);
      HttpEntity httpEntity = httpResponse.getEntity();
      xml = EntityUtils.toString(httpEntity, "UTF-8");
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    } catch (ClientProtocolException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    return xml;
  } 

  /**
   * 获取XML DOM元素
   *
   * @param XML
   *      string
   * */
  public Document getDomElement(InputStream is) {
    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) {
      Log.e("Error: ", e.getMessage());
      return null;
    } catch (SAXException e) {
      Log.e("Error: ", e.getMessage());
      return null;
    } catch (IOException e) {
      Log.e("Error: ", e.getMessage());
      return null;
    } 

    return doc;
  } 

  public Document getDomDocumentUpdate(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) {
      Log.e("Error: ", e.getMessage());
      return null;
    } catch (SAXException e) {
      Log.e("Error: ", e.getMessage());
      return null;
    } catch (IOException e) {
      Log.e("Error: ", e.getMessage());
      return null;
    } 

    return doc;
  } 

  /**
   * 获取节点值
   *
   * @param elem
   *      element
   */
  public final String getElementValue(Node elem) {
    Node child;
    if (elem != null) {
      if (elem.hasChildNodes()) {
        for (child = elem.getFirstChild(); child != null; child = child
            .getNextSibling()) {
          if (child.getNodeType() == Node.TEXT_NODE) {
            return child.getNodeValue();
          }
        }
      }
    }
    return "";
  } 

  /**
   * 获取节点值
   *
   * @param Element
   *      node
   * @param key
   *      string
   * */
  public String getValue(Element item, String str) {
    NodeList n = item.getElementsByTagName(str);
    return this.getElementValue(n.item(0));
  }
  //XML文件有更新后，调用此方法
  public void output(Document node, String filename) {
    TransformerFactory transFactory = TransformerFactory.newInstance();
    try {
      Transformer transformer = transFactory.newTransformer();
      // 设置各种输出属性
      transformer.setOutputProperty("encoding", "UTF-8");
      transformer.setOutputProperty("indent", "yes");
      DOMSource source = new DOMSource(node);
      // 将待转换输出节点赋值给DOM源模型的持有者(holder)
      // /source.setNode(node);
      StreamResult result = new StreamResult();
      if (filename == null) {
        // 设置标准输出流为transformer的底层输出目标
        result.setOutputStream(System.out);
      } else {
        result.setOutputStream(new FileOutputStream(filename));
      }
      // 执行转换从源模型到控制台输出流
      transformer.transform(source, result);
    } catch (TransformerConfigurationException e) {
      e.printStackTrace();
    } catch (TransformerException e) {
      e.printStackTrace();
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    }
  } 

  public String writeXml() {
    XmlSerializer xml = Xml.newSerializer();
    StringWriter writer = new StringWriter();
    try {
      xml.setOutput(writer);
      xml.startDocument("UTF-8", true);
      xml.startTag("", "blog"); 

      xml.startTag("", "message");
      xml.attribute("", "name", "xia");
      xml.startTag("", "age");
      xml.text("22");
      xml.endTag("", "age"); 

      xml.startTag("", "hobby");
      xml.text("play");
      xml.endTag("", "hobby"); 

      xml.startTag("", "hight");
      xml.text("165");
      xml.endTag("", "hight");
      xml.endTag("", "message"); 

      xml.startTag("", "message");
      xml.attribute("", "name", "chen");
      xml.startTag("", "age");
      xml.text("21");
      xml.endTag("", "age"); 

      xml.startTag("", "hobby");
      xml.text("swin");
      xml.endTag("", "hobby"); 

      xml.startTag("", "hight");
      xml.text("170");
      xml.endTag("", "hight");
      xml.endTag("", "message"); 

      xml.endTag("", "blog");
      xml.endDocument(); 

    } catch (Exception e) {
      throw new RuntimeException(e);
    } 

    return writer.toString();
  } 

  public boolean Write(String Filepath, String txt) {
    FileOutputStream fos = null;
    if (Environment.getExternalStorageState() != null) {// 这个方法在试探终端是否有sdcard!
      File path = new File("sdcard/test");// 创建目录
      File f = new File(Filepath);// 创建文件
      if (!path.exists()) {// 目录不存在返回false
        path.mkdirs();// 创建一个目录
      }
      if (!f.exists()) {// 文件不存在返回false
        try {
          f.createNewFile();
          fos = new FileOutputStream(f);
          fos.write((txt).getBytes("UTF-8"));
          fos.close();
        } catch (IOException e) {
          // TODO Auto-generated catch block
          e.printStackTrace();
        }// 创建一个文件
      } 

    }
    return true;
  } 

  private static XMLParser uniqueInstance = null; 

  public static XMLParser getInstance() {
    if (uniqueInstance == null) {
      uniqueInstance = new XMLParser();
    }
    return uniqueInstance;
  }
}

上面的这个类中用了单例！分别定义了XML的创建，获取XML的节点值，更新后执行的操作！

MainActivity：

public class MainActivity extends Activity {
  public static final String XMLPath = "sdcard/test/message.xml";
  private Button create = null; 

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    create = (Button) findViewById(R.id.create);
  } 

  // 自动创建XML
  private void createXml() {
    // sdcard/test/message.xml
    XMLParser.getInstance().Write(XMLPath,
        XMLParser.getInstance().writeXml());
  } 

  // 遍历节点，找到特定节点并进行更换！
  private void selectNode() {
    Document document = null;
    try {
      FileInputStream fin = new FileInputStream(XMLPath);
      document = XMLParser.getInstance().getDomElement(fin);
      Node root = document.getDocumentElement();
      if (root.hasChildNodes()) {
        NodeList ftpnodes = root.getChildNodes();
        Log.e("eee", root.getNodeName());// 根节点 blog 

        for (int i = 0; i < ftpnodes.getLength(); i++) {
          NodeList ftplist = ftpnodes.item(i).getChildNodes();
          Node su = ftpnodes.item(i);
          Log.e("eee", su.getNodeName());// message
          Element e = (Element) ftpnodes.item(i);
          Log.e("eee", e.getAttribute("name"));// message= xia
          for (int k = 0; k < ftplist.getLength(); k++) {
            Node subnode = ftplist.item(k);
            Log.e("eee",
                " subnode.getNodeName()"
                    + subnode.getNodeName());
            Log.e("eee",
                "subnode.getNodeType()" + subnode.getNodeType());
            Log.e("eee", subnode.getFirstChild().getNodeValue());
            if (subnode.getNodeType() == Node.ELEMENT_NODE
                && subnode.getNodeName().equals("hight")) {
              subnode.getFirstChild().setNodeValue("175");
              XMLParser.getInstance().output(document, XMLPath);
            }
          }
        }
      } 

    } catch (Exception e) { 

    }
  } 

  // 添加一个新的根节点
  private void insertNode() {
    Document document = null;
    try {
      FileInputStream fin = new FileInputStream(XMLPath);
      document = XMLParser.getInstance().getDomElement(fin);
      // 插入根节点message
      /**
       * <message name="wang"> <hight>180</hight> <age>22</age> </message>
       *
       * */
      Element eltStu = document.createElement("message");
      Element eltName = document.createElement("hight");
      Element eltAge = document.createElement("age");
      Attr attr = document.createAttribute("name");
      attr.setValue("wang");
      Text txtName = document.createTextNode("180");
      Text txtAge = document.createTextNode("22");
      eltName.appendChild(txtName);
      eltAge.appendChild(txtAge);
      eltStu.appendChild(eltName);
      eltStu.appendChild(eltAge);
      eltStu.setAttributeNode(attr);
      Element eltRoot = document.getDocumentElement();
      eltRoot.appendChild(eltStu);
      XMLParser.getInstance().output(document, XMLPath);
    } catch (Exception e) { 

    }
  } 

  private void instertChildNode() {
    Document document = null;
    try {
      FileInputStream fin = new FileInputStream(XMLPath);
      document = XMLParser.getInstance().getDomElement(fin);
      // 在某个根节点下面添加节点
      /**
       * <message name="wang"> <hight>180</hight> <age>22</age>
       * <hobby>music</hobby>//这句是新添加的 </message>
       *
       * */
      Node root = document.getDocumentElement();
      NodeList ftpnodes = root.getChildNodes();
      Log.e("eee", root.getNodeName());// 根节点 blog
      NodeList ftplist = ftpnodes.item(1).getChildNodes();
      Node su = ftpnodes.item(1);
      Log.e("eee", su.getNodeName());// message
      Element e = (Element) ftpnodes.item(5);// message= wang
      Log.e("eee", e.getAttribute("name"));
      if (e.getAttribute("name").equals("wang")) {
        Element elthoby = document.createElement("hobby");
        Text txthoby = document.createTextNode("music");
        elthoby.appendChild(txthoby);
        Node stNode = document.getElementsByTagName("message").item(2);
        stNode.appendChild(elthoby);
      }
      XMLParser.getInstance().output(document, XMLPath);
    } catch (Exception e) {
    }
  } 

  private void removeNode() {
    Document document = null;
    try {
      FileInputStream fin = new FileInputStream(XMLPath);
      document = XMLParser.getInstance().getDomElement(fin);
      // 删除blog下的message的0个节点
      NodeList nl = document.getElementsByTagName("message");
      Node nodeDel = (Element) nl.item(0);
      nodeDel.getParentNode().removeChild(nodeDel);
      XMLParser.getInstance().output(document, XMLPath);
    } catch (Exception e) {
    }
  } 

  @Override
  protected void onDestroy() {
    super.onDestroy();
  }
}

最后记得添加读写SDcard的权限！

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