pull 方式解析xml文件

关于xml的解析，网上提供了许多的解析方式；sax和pull和dom的各有优缺点；

但常用的还是pull这里我就自己理解的pull来解释；pull是基于事件触发的可以认为是流形式的；姑且认为读到一个tag或一串字符都会停顿；

1，数据结构类：

public class Book {private int id;private String name;private float price;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public float getPrice() {return price;}public void setPrice(float price) {this.price = price;}@Overridepublic String toString() {return "id:" + id + ", name:" + name + ", price:" + price;}}

2，xml解析文件：

public class PullBookParser  {private String TAG = "PullBookParser";private Context context = null;public PullBookParser(Context context) {// TODO Auto-generated constructor stubthis.context = context;}public List<Book> readXml(InputStream is) throws XmlPullParserException,IOException {List<Book> books = null;Book book = null;XmlResourceParser parser = context.getResources().getXml(R.xml.books);// XmlPullParser parser = Xml.newPullParser(); //// 由android.util.Xml创建一个XmlPullParser实例// parser.setInput(is, "UTF-8"); // 设置输入流 并指明编码方式int eventType = parser.getEventType();while (eventType != XmlResourceParser.END_DOCUMENT) {//这里体现了pull的流形式，事件主要为eventtypeswitch (eventType) {case XmlResourceParser.START_DOCUMENT:books = new ArrayList<Book>();break;case XmlResourceParser.START_TAG:String name = parser.getName();if (name.equalsIgnoreCase("book")) {book = new Book();int id = Integer.parseInt(parser.getAttributeValue(null,"id"));book.setId(id);} else if (null != book) {if (name.equalsIgnoreCase("name")) {book.setName(parser.nextText());} else if (name.equalsIgnoreCase("price")) {float price = Float.parseFloat(parser.nextText());book.setPrice(price);}}break;case XmlPullParser.END_TAG:// 结束元素事件if (parser.getName().equalsIgnoreCase("book") && book != null) {books.add(book);book = null;}break;default:break;}eventType = parser.next();}return books;}@Overridepublic String serialize(List<Book> books) throws Exception {// XmlPullParserFactory factory = XmlPullParserFactory.newInstance();// XmlSerializer serializer = factory.newSerializer();Log.i(TAG, "laskdjf:" + books.toString());XmlSerializer serializer = Xml.newSerializer(); // 由android.util.Xml创建一个XmlSerializer实例StringWriter writer = new StringWriter();serializer.setOutput(writer); // 设置输出方向为writerserializer.startDocument("UTF-8", true);serializer.startTag("", "books");for (Book book : books) {//流形式页在这里体现serializer.startTag("", "book");serializer.attribute("", "id", book.getId() + "");serializer.startTag("", "name");serializer.text(book.getName());serializer.endTag("", "name");serializer.startTag("", "price");serializer.text(book.getPrice() + "");serializer.endTag("", "price");serializer.endTag("", "book");}serializer.endTag("", "books");serializer.endDocument();return writer.toString();}public void writeFile(String xml) {try {Log.i(TAG, xml);File file = new File("books.xml");if (file.exists()) {file.delete();}//FileOutputStream fos = new FileOutputStream(file);FileOutputStream fos = context.openFileOutput("books.xml", Context.MODE_PRIVATE);fos.write(xml.getBytes("UTF-8"));fos.close();} catch (Exception e) {Log.e(TAG, e.getMessage());}}}

3，调用MainActivity.java中

public class MainActivity extends Activity {private Button readButton = null;private Button writeButton = null;private String TAG = "MainActivity";PullBookParser parser = null;List<Book> books = null;private Context context = this;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);readButton = (Button) findViewById(R.id.read);writeButton = (Button) findViewById(R.id.write);readButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubtry {parser = new PullBookParser(context);books = parser.readXml(null);for (Book book : books) {Log.i(TAG, book.toString());}} catch (Exception e) {// Log.e(TAG, e.getMessage());e.printStackTrace();}}});writeButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {String xml = null;try {xml = parser.serialize(books);parser.writeFile(xml);} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();} // 序列化}});}}

4，主布局文件activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <Button        android:id="@+id/read"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="读取xml" />    <Button        android:id="@+id/write"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="写入xml" />    <Button        android:id="@+id/update"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="更新xml" /></LinearLayout>

5，初始xml文件book.xml放在res/xml/book.xml中；

<?xml version="1.0" encoding="utf-8"?>  <books>      <book id="1001">          <name>Thinking In Java</name>          <price>80.00</price>      </book>      <book id="1002">          <name>Core Java</name>          <price>90.00</price>      </book>      <book id="1003">          <name>Hello, Andriod</name>          <price>100.00</price>      </book>  </books>  

6,在/data/data/包命/files/books.xml中生成的格式同5；