Java SAX解析器 - 查詢XML文檔
演示示例
這是我們需要查詢卷號：rollno 輸入文本文件：393
UserHandler.java
package com.yiibai.xml; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; public class UserHandler extends DefaultHandler { boolean bFirstName = false; boolean bLastName = false; boolean bNickName = false; boolean bMarks = false; String rollNo = null; @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { if (qName.equalsIgnoreCase("student")) { rollNo = attributes.getValue("rollno"); } if(("393").equals(rollNo) && qName.equalsIgnoreCase("student")){ System.out.println("Start Element :" + qName); } if (qName.equalsIgnoreCase("firstname")) { bFirstName = true; } else if (qName.equalsIgnoreCase("lastname")) { bLastName = true; } else if (qName.equalsIgnoreCase("nickname")) { bNickName = true; } else if (qName.equalsIgnoreCase("marks")) { bMarks = true; } } @Override public void endElement(String uri, String localName, String qName) throws SAXException { if (qName.equalsIgnoreCase("student")) { if(("393").equals(rollNo) && qName.equalsIgnoreCase("student")) System.out.println("End Element :" + qName); } } @Override public void characters(char ch[], int start, int length) throws SAXException { if (bFirstName && ("393").equals(rollNo)) { //age element, set Employee age System.out.println("First Name: " + new String(ch, start, length)); bFirstName = false; } else if (bLastName && ("393").equals(rollNo)) { System.out.println("Last Name: " + new String(ch, start, length)); bLastName = false; } else if (bNickName && ("393").equals(rollNo)) { System.out.println("Nick Name: " + new String(ch, start, length)); bNickName = false; } else if (bMarks && ("393").equals(rollNo)) { System.out.println("Marks: " + new String(ch, start, length)); bMarks = false; } } }
SAXQueryDemo.java
package com.yiibai.xml; import java.io.File; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; public class SAXQueryDemo { public static void main(String[] args){ try { File inputFile = new File("input.txt"); SAXParserFactory factory = SAXParserFactory.newInstance(); SAXParser saxParser = factory.newSAXParser(); UserHandler userhandler = new UserHandler(); saxParser.parse(inputFile, userhandler); } catch (Exception e) { e.printStackTrace(); } } } class UserHandler extends DefaultHandler { boolean bFirstName = false; boolean bLastName = false; boolean bNickName = false; boolean bMarks = false; String rollNo = null; @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { if (qName.equalsIgnoreCase("student")) { rollNo = attributes.getValue("rollno"); } if(("393").equals(rollNo) && qName.equalsIgnoreCase("student")){ System.out.println("Start Element :" + qName); } if (qName.equalsIgnoreCase("firstname")) { bFirstName = true; } else if (qName.equalsIgnoreCase("lastname")) { bLastName = true; } else if (qName.equalsIgnoreCase("nickname")) { bNickName = true; } else if (qName.equalsIgnoreCase("marks")) { bMarks = true; } } @Override public void endElement(String uri, String localName, String qName) throws SAXException { if (qName.equalsIgnoreCase("student")) { if(("393").equals(rollNo) && qName.equalsIgnoreCase("student")) System.out.println("End Element :" + qName); } } @Override public void characters(char ch[], int start, int length) throws SAXException { if (bFirstName && ("393").equals(rollNo)) { //age element, set Employee age System.out.println("First Name: " + new String(ch, start, length)); bFirstName = false; } else if (bLastName && ("393").equals(rollNo)) { System.out.println("Last Name: " + new String(ch, start, length)); bLastName = false; } else if (bNickName && ("393").equals(rollNo)) { System.out.println("Nick Name: " + new String(ch, start, length)); bNickName = false; } else if (bMarks && ("393").equals(rollNo)) { System.out.println("Marks: " + new String(ch, start, length)); bMarks = false; } } }
這將產生以下結果：
Start Element :student
First Name: dinkar
Last Name: kad
Nick Name: dinkar
Marks: 85
End Element :student