android讀寫XML

input.xml文件存放學生信息

<?xml version="1.0" encoding="UTF-8" standalone="no" ?> - <學生花名冊> - <學生 性別="男"> <姓名>吳鳳龍</姓名> <年齡>30</年齡> <電話>68888888</電話> </學生> - <學生 性別="男"> <姓名>張井滿</姓名> <年齡>32</年齡> <電話>88888888</電話> </學生> </學生花名冊>

 

 讀取XML的代碼：

 

private ArrayList<SMSUnit> readSMSXMLFile(String path, String filename) { File inFile = new File(path, filename); try { inFile.createNewFile(); } catch (IOException e) { e.printStackTrace(); } // 爲解析XML作準備，創建DocumentBuilderFactory實例,指定DocumentBuilder DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = null; try { db = dbf.newDocumentBuilder(); } catch (ParserConfigurationException pce) { System.err.println(pce); // 出異常時輸出異常信息，然後退出，下同 System.exit(1); } Document doc = null; try { doc = db.parse(inFile); } catch (DOMException dom) { System.err.println(dom.getMessage()); System.exit(1); } catch (IOException ioe) { System.err.println(ioe); System.exit(1); } // 下面是解析XML的全過程，比較簡單，先取根元素"學生花名冊" Element root = doc.getDocumentElement(); // 取"學生"元素列表 NodeList students = root.getElementsByTagName("學生"); for (int i = 0; i < students.getLength(); i++) { // 依次取每個"學生"元素 Element student = (Element) students.item(i); // 創建一個學生的Bean實例 StudentBean studentBean = new StudentBean(); // 取學生的性別屬性 studentBean.setSex(student.getAttribute("性別")); // 取"姓名"元素，下面類同 NodeList names = student.getElementsByTagName("姓名"); if (names.getLength() == 1) { Element e = (Element) names.item(0); Text t = (Text) e.getFirstChild(); studentBean.setName(t.getNodeValue()); } NodeList ages = student.getElementsByTagName("年齡"); if (ages.getLength() == 1) { Element e = (Element) ages.item(0); Text t = (Text) e.getFirstChild(); studentBean.setAge(Integer.parseInt(t.getNodeValue())); } NodeList phones = student.getElementsByTagName("電話"); if (phones.getLength() == 1) { Element e = (Element) phones.item(0); Text t = (Text) e.getFirstChild(); studentBean.setPhone(t.getNodeValue()); } student_Vector.add(studentBean); } } 

 

生成XML的代碼：

 

private void writeXMLFile(String outFile) throws Exception { // 爲解析XML作準備，創建DocumentBuilderFactory實例,指定DocumentBuilder DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = null; try { db = dbf.newDocumentBuilder(); } catch (ParserConfigurationException pce) { System.err.println(pce); System.exit(1); } Document doc = null; doc = db.newDocument(); // 下面是建立XML文檔內容的過程，先建立根元素"學生花名冊" Element root = doc.createElement("學生花名冊"); // 根元素添加上文檔 doc.appendChild(root); // 取學生信息的Bean列表 for (int i = 0; i < student_Vector.size(); i++) { // 依次取每個學生的信息 StudentBean studentBean = (StudentBean) student_Vector.get(i); // 建立"學生"元素，添加到根元素 Element student = doc.createElement("學生"); student.setAttribute("性別", studentBean.getSex()); root.appendChild(student); // 建立"姓名"元素，添加到學生下面，下同 Element name = doc.createElement("姓名"); student.appendChild(name); Text tName = doc.createTextNode(studentBean.getName()); name.appendChild(tName); Element age = doc.createElement("年齡"); student.appendChild(age); Text tAge = doc .createTextNode(String.valueOf(studentBean.getAge())); age.appendChild(tAge); Element phone = doc.createElement("電話"); student.appendChild(phone); Text tPhone = doc.createTextNode(studentBean.getPhone()); phone.appendChild(tPhone); } // 把XML文檔輸出到指定的文件 Transformer t = TransformerFactory.newInstance().newTransformer(); t.setOutputProperty("indent", "yes"); t.transform(new DOMSource(doc), new StreamResult(new FileOutputStream( outFile))); } 

 

輔助類，用於存儲學生信息：

 

public class StudentBean { private String sex; // 學生性別 private String name; // 學生姓名 private int age; // 學生年齡 private String phone; // 電話號碼 public void setSex(String s) { sex = s; } public void setName(String s) { name = s; } public void setAge(int a) { age = a; } public void setPhone(String s) { phone = s; } public String getSex() { return sex; } public String getName() { return name; } public int getAge() { return age; } public String getPhone() { return phone; } } 

 

上面在生成XML文件時有問題：（只要有這面的代碼，在android模擬器上就異常，而且連Oncreate()都不運行，在真機上運行無反應）

不知道爲什麼會這樣，希望大俠們指教：

try { javax.xml.transform.Transformer xformer = javax.xml.transform.TransformerFactory .newInstance().newTransformer(); xformer.setOutputProperty(OutputKeys.ENCODING, encoding); // Prepare the DOM document for writing javax.xml.transform.dom.DOMSource source = new javax.xml.transform.dom.DOMSource( doc); // Prepare the output file StringWriter writer = new StringWriter(); Result result = new StreamResult(writer); // Write the DOM document to the file xformer.transform(source, result); Log.v(TAG, writer.toString()); } catch (javax.xml.transform.TransformerConfigurationException e) { Log.v(TAG, "TransformerConfigurationException"); e.printStackTrace(); } catch (javax.xml.transform.TransformerException e) { Log.v(TAG, "TransformerException"); e.printStackTrace(); } 

 

明白了，從新看了下API

javax.xml.transform這個包是Since: API Level 8也就是說它是android2.2的api，在android 1.5當然不能用。

我從新找了下API，發現org.xmlpull.v1這個包下的XmlSerializer也可以實現以上的需求：Since: API Level 1

 

貼個XmlSerializer的例子：

 

package com.hwttnet.wu.testcreatexml; import java.io.FileNotFoundException; import java.io.IOException; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.io.StringWriter; import org.xmlpull.v1.XmlSerializer; import android.app.Activity; import android.os.Bundle; import android.util.Log; import android.util.Xml; import android.widget.TextView; public class testcreatexml extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) findViewById(R.id.mytextview); String str = writeXml(); tv.setText(str); Log.v("testcreatexml", str); Write("blog.xml", writeXml()); } private String writeXml() { XmlSerializer serializer = Xml.newSerializer(); StringWriter writer = new StringWriter(); try { serializer.setOutput(writer); // <?xml version="1.0″ encoding="UTF-8″ standalone="yes"?> serializer.startDocument("UTF-8", true); // <blog number="1″> serializer.startTag("", "blog"); serializer.attribute("", "number", String.valueOf(1)); // <message data="2009-09-23″> serializer.startTag("", "message"); serializer.attribute("", "date", "2009-09-23"); // <title>Android XML</title> serializer.startTag("", "title"); serializer.text("Android XML"); serializer.endTag("", "title"); // <url>http://www.moandroid.com/?p=508</url> serializer.startTag("", "url"); serializer.text("http://www.moandroid.com/?p=508"); serializer.endTag("", "url"); // </message> serializer.endTag("", "message"); // </blog> serializer.endTag("", "blog"); serializer.endDocument(); return writer.toString(); } catch (Exception e) { throw new RuntimeException(e); } } public boolean Write(String path, String txt) { try { OutputStream os = openFileOutput(path, MODE_PRIVATE); OutputStreamWriter osw = new OutputStreamWriter(os); osw.write(txt); osw.close(); os.close(); } catch (FileNotFoundException e) { return false; } catch (IOException e) { return false; } return true; } }