Android学习笔记之XML解析（SAX）

SAX是一种占用内存少且解析速度快的解析器，它采用的是事件启动，它不需要解析完整个文档，而是按照内容顺序 看文档某个部分是否符合xml语法，如果符合就触发相应的事件，所谓的事件就是些回调方法（callback）,这些方法 定义在ContentHandler中，下面是其主要方法：

startDocument:当遇到文档的时候就触发这个事件 调用这个方法 可以在其中做些预处理工作

startElement: (String namespaceURI,String localName,String qName,Attributes atts)当遇开始标签的时候就会触发这个方法。

endElement（String uri,String localName,String name）：当遇到结束标签时触发这个事件，调用此法可以做些善后工作。

charachers(char [] ch,int start,int length):当遇到xml内容时触发这个方法，用new String(ch,start,length)可以接受内容。

MyContentHandler.java

package mars.xml; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; public class MyContentHandler extends DefaultHandler { String hisname, address, money, sex, status; String tagName; public void startDocument() throws SAXException { System.out.println("````````begin````````"); } public void endDocument() throws SAXException { System.out.println("````````end````````"); } public void startElement(String namespaceURI, String localName, String qName, Attributes attr) throws SAXException { tagName = localName; if (localName.equals("worker")) { //获取标签的全部属性 for (int i = 0; i < attr.getLength(); i++) { System.out.println(attr.getLocalName(i) + "=" + attr.getValue(i)); } } } public void endElement(String namespaceURI, String localName, String qName) throws SAXException { //在workr标签解析完之后，会打印出所有得到的数据 tagName = ""; if (localName.equals("worker")) { this.printout(); } } public void characters(char[] ch, int start, int length) throws SAXException { if (tagName.equals("name")) hisname = new String(ch, start, length); else if (tagName.equals("sex")) sex = new String(ch, start, length); else if (tagName.equals("status")) status = new String(ch, start, length); else if (tagName.equals("address")) address = new String(ch, start, length); else if (tagName.equals("money")) money = new String(ch, start, length); } private void printout() { System.out.print("name: "); System.out.println(hisname); System.out.print("sex: "); System.out.println(sex); System.out.print("status: "); System.out.println(status); System.out.print("address: "); System.out.println(address); System.out.print("money: "); System.out.println(money); System.out.println(); } }

XMLActitity.java

package mars.xml; import java.io.StringReader; import javax.xml.parsers.SAXParserFactory; import mars.utils.HttpDownloader; import org.xml.sax.InputSource; import org.xml.sax.XMLReader; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class XMLActitity extends Activity { /** Called when the activity is first created. */ private Button parseButton ; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); parseButton = (Button)findViewById(R.id.parseButton); parseButton.setOnClickListener(new ParseButtonListener()); } class ParseButtonListener implements OnClickListener{ public void onClick(View v) { HttpDownloader hd = new HttpDownloader(); String resultStr = hd.download("http://192.168.1.107:8081/voa1500/test.xml"); System.out.println(resultStr); try{ //创建一个SAXParserFactory SAXParserFactory factory = SAXParserFactory.newInstance(); XMLReader reader = factory.newSAXParser().getXMLReader(); //为XMLReader设置内容处理器 reader.setContentHandler(new MyContentHandler()); //开始解析文件 reader.parse(new InputSource(new StringReader(resultStr))); } catch(Exception e){ e.printStackTrace(); } } } }