Android提高第七篇之XML解析与生成.doc

本文使用SAX来解析XML，在Android里面可以使用SAX和DOM，DOM需要把整个XML文件读入内存再解析，比较消耗内存，而SAX基于事件驱动的处理方式，可以在各节点触发回调函数，不过SAX适合节点结构简单的XML文档，复杂的XML文档在后期的节点深度处理会有点麻烦。本文要解析的test.xml文件如下：view plaincopy to clipboardprint?01. 02. 03. testSAX 04. 05. hellogv 06. /hellogv 07. 08. testSAX hellogv /hellogv 解析如上XML的结果如下： 使用SAX解析，需要定义SAXParserFactory(使应用程序能够配置和获取基于 SAX 的解析器以解析 XML 文档)，SAXParser(从各种输入源解析 XML)，XMLReader(使用回调函数读取 XML 文档)，其中XMLReader是个关键。XMLReader可以为解析XML定义各种回调函数，“条件符合”的时候触发这些回调函数。view plaincopy to clipboardprint?01.SAXParserFactory factory = SAXParserFactory.newInstance(); 02.SAXParser parser = factory.newSAXParser(); 03.XMLReader reader = parser.getXMLReader(); 04.reader.setContentHandler(handler); 05.reader.parse(new InputSource(testSAX.this.getResources() 06. .openRawResource(R.raw.test); SAXParserFactory factory = SAXParserFactory.newInstance();SAXParser parser = factory.newSAXParser();XMLReader reader = parser.getXMLReader();reader.setContentHandler(handler);reader.parse(new InputSource(testSAX.this.getResources().openRawResource(R.raw.test); 在这段代码里，XMLReader就调用继承DefaultHandler的SAXHandler。DefaultHandler已实现ContentHandler, DTDHandler, EntityResolver, ErrorHandler等接口，包含常见读取XML的操作，具体请看下面的SAXHandler.java源码。生成XML的结果如下：上图是读取各节点之后，使用XmlSerializer重新组合并输出XML字符串。本文的main.xml代码如下：view plaincopy to clipboardprint?01. 02. 05. 06. 09. 11. 13. 14. SAXHandler.java的源码如下：view plaincopy to clipboardprint?01.package com.testSAX; 02. 03.import java.util.ArrayList; 04.import org.xml.sax.Attributes; 05.import org.xml.sax.SAXException; 06.import org.xml.sax.helpers.DefaultHandler; 07. 08.import android.util.Log; 09. 10.public class SAXHandler extends DefaultHandler 11. private ArrayList keys = new ArrayList();/保存字段名称 12. private ArrayList values = new ArrayList();/保存值 13. Override 14. public void startDocument() throws SAXException 15. super.startDocument(); 16. 17. 18. 19. Override 20. public void endDocument() throws SAXException 21. super.endDocument(); 22. 23. 24. Override 25. public void startElement(String uri, String localName, String qName, 26. Attributes attributes) throws SAXException 27. /保存开始标记 28. keys.add(startTag); 29. values.add(localName); 30. 31. Log.e(startTag,localName); 32. /保存属性值 33. for ( int i = 0; i attributes.getLength(); i+ ) 34. keys.add(Attr); 35. String str=new String2; 36. str0=attributes.getLocalName(i); 37. str1=attributes.getValue(i); 38. values.add(str); 39. Log.e(Attr,str0+=+str1); 40. 41. 42. 43. Override 44. public void endElement(String uri, String localName, String qName) 45. throws SAXException 46. /保存结束标记 47. keys.add(endTag); 48. values.add(localName); 49. Log.e(endTag,localName); 50. 51. 52. Override 53. public void characters(char ch, int start, int length) 54. throws SAXException 55. String value = new String(ch, start, length); 56. value = value.trim(); 57. if (value.length() = 0) 58. return; 59. 60. keys.add(text); 61. values.add(value); 62. Log.e(text,value); 63. 64. 65. public ArrayList GetKeys() 66. 67. return keys; 68. 69. 70. public ArrayList GetValues() 71. 72. return values; 73. 74. 75. 76. package com.testSAX;import java.util.ArrayList;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;import android.util.Log;public class SAXHandler extends DefaultHandler private ArrayList keys = new ArrayList();/保存字段名称 private ArrayList values = new ArrayList();/保存值Overridepublic void startDocument() throws SAXException super.startDocument();Overridepublic void endDocument() throws SAXException super.endDocument();Overridepublic void startElement(String uri, String localName, String qName,Attributes attributes) throws SAXException /保存开始标记keys.add(startTag);values.add(localName);Log.e(startTag,localName);/保存属性值for ( int i = 0; i attributes.getLength(); i+ )keys.add(Attr);String str=new String2;str0=attributes.getLocalName(i);str1=attributes.getValue(i);values.add(str);Log.e(Attr,str0+=+str1);Overridepublic void endElement(String uri, String localName, String qName)throws SAXException /保存结束标记keys.add(endTag);values.add(localName);Log.e(endTag,localName);Overridepublic void characters(char ch, int start, int length)throws SAXException String value = new String(ch, start, length);value = value.trim();if (value.length() = 0)return;keys.add(text);values.add(value);Log.e(text,value);public ArrayList GetKeys()return keys;public ArrayList GetValues()return values; testSAX.java的源码如下：view plaincopy to clipboardprint?01.package com.testSAX; 02. 03.import java.io.StringWriter; 04. 05.import javax.xml.parsers.SAXParser; 06.import javax.xml.parsers.SAXParserFactory; 07. 08.import org.xml.sax.InputSource; 09.import org.xml.sax.XMLReader; 10.import org.xmlpull.v1.XmlSerializer; 11. 12.import android.app.Activity; 13.import android.os.Bundle; 14. 15.import android.util.Xml; 16.import android.view.View; 17.import android.widget.Button; 18.import android.widget.EditText; 19. 20.public class testSAX extends Activity 21. /* Called when the activity is first created. */ 22. Button btnSAX, btnOutput; 23. EditText memo; 24. SAXHandler handler = new SAXHandler(); 25. 26. 27. Override 28. public void onCreate(Bundle savedInstanceState) 29. super.onCreate(savedInstanceState); 30. setContentView(R.layout.main); 31. btnSAX = (Button) this.findViewById(R.id.btnSAX); 32. btnSAX.setOnClickListener(new ClickEvent(); 33. btnOutput = (Button) this.findViewById(R.id.btnOutput); 34. btnOutput.setOnClickListener(new ClickEvent(); 35. memo = (EditText) this.findViewById(R.id.EditText01); 36. 37. 38. 39. class ClickEvent implements View.OnClickListener 40. 41. Override 42. public void onClick(View v) 43. if (v = btnSAX) /解析XML，并保存标记，属性等值 44. try 45. SAXParserFactory factory = SAXParserFactory.newInstance(); 46. SAXParser parser = factory.newSAXParser(); 47. XMLReader reader = parser.getXM