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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