SAX介绍
SAX是一种事件驱动的流式XML文件处理方式，区别与DOM方式的是不需要在内存中建一棵DOM树，而是根据读取XML时遇到的标签事件来顺序处理，因此具有速度快，内存占用上的优点。
XML生成
代码如下：
1 package com.test.sax;
2
3 import javax.xml.transform.OutputKeys;
4 import javax.xml.transform.Result;
5 import javax.xml.transform.Transformer;
6 import javax.xml.transform.TransformerConfigurationException;
7 import javax.xml.transform.sax.SAXTransformerFactory;
8 import javax.xml.transform.sax.TransformerHandler;
9 import javax.xml.transform.stream.StreamResult;
10
11 import org.xml.sax.SAXException;
12 import org.xml.sax.helpers.AttributesImpl;
13
14 public class TestCreateXml {
15
16 public static void main(String[] args) {
17 //创建SAXTransformerFactory实例
18 SAXTransformerFactory factory = (SAXTransformerFactory) SAXTransformerFactory.newInstance();
19 try {
20 //创建TransformerHandler实例
21 TransformerHandler handler = factory.newTransformerHandler();
22 //创建Transformer实例
23 Transformer transformer = handler.getTransformer();
24 //设置输出的xml属性，encoding为编码，
25 transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
26 //indent是确保输出的xml文件能够自动换行
27 transformer.setOutputProperty(OutputKeys.INDENT, "yes");
28
29 //创建Result对象，将Result对象加载到TransHandler中
30 // 注意：1、这一步必须在Transformer.setOutputProperty()之后，不然设置的xml属性将不生效
31 // 2、这一步也必须在TransformerHandler.startDocument()之前，不然会报错。
32 // 分析源码后发现，startDocument()会先判断result是否为空，为空则报错
33 Result result = new StreamResult("src/test-sax-create.xml");
34 handler.setResult(result);
35
36 // 创建属性Attribute对象
37 AttributesImpl attr = new AttributesImpl();
38 //开始写文件
39 handler.startDocument();
40 //写入根节点conpany
41 handler.startElement("", "", "conpany", attr);
42
43 //清空属性，
44 attr.clear();
45 //设置属性
46 attr.addAttribute( "", "", "name", "", "1");
47 //写入根节点的子节点book
48 handler.startElement("", "", "department", attr);
49
50 attr.clear();
51 //分别写入book节点的子节点
52 attr.addAttribute( "", "", "name", "", "employee1");
53 attr.addAttribute( "", "", "id", "", "1");
54 handler.startElement("", "", "employee", attr);
55 //写入子节点内容
56 handler.characters("123".toCharArray(), 0, "123".toCharArray().length);
57 //写入子节点末尾
58 handler.endElement("", "", "employee");
59 //写入department节点末尾
60 handler.endElement("", "", "department");
61 //写入根节点末尾
62 handler.endElement("", "", "conpany");
63 //写文件结束
64 handler.endDocument();
65 } catch (TransformerConfigurationException e) {
66 e.printStackTrace();
67 } catch (SAXException e) {
68 e.printStackTrace();
69 }
70 }
71 }
生成文件如下：
XML解析
代码如下：
1 package com.test.sax;
2
3 import java.io.IOException;
4 import java.util.ArrayList;
5 import java.util.HashMap;
6 import java.util.List;
7 import java.util.Map;
8
9 import javax.xml.parsers.ParserConfigurationException;
10 import javax.xml.parsers.SAXParser;
11 import javax.xml.parsers.SAXParserFactory;
12
13 import org.xml.sax.Attributes;
14 import org.xml.sax.SAXException;
15 import org.xml.sax.helpers.DefaultHandler;
16
17
18 public class TestParseXml {
19
20 public static void main(String[] args) throws SAXException, IOException, ParserConfigurationException {
21 //创建SAXTransformerFactory实例
22 SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
23 //创建TransformerHandler实例
24 SAXParser saxParser = saxParserFactory.newSAXParser();
25
26 MyHandler myHandler = new MyHandler();
27
28 saxParser.parse(TestParseXml.class.getClassLoader().getResourceAsStream("test.xml"), myHandler);
29 }
30
31 }
32
33
34 class MyHandler extends DefaultHandler{
35
36 /**
37 * 开始解析文档时，调用的方法
38 */
39 @Override
40 public void startDocument() throws SAXException {
41 System.out.println("---------startDocument-------");
42 }
43
44 /**
45 * 文档解析完结时，调用的方法
46 */
47 @Override
48 public void endDocument() throws SAXException {
49 System.out.println("---------endDocument-------");
50 super.endDocument();
51 }
52
53 /**
54 * 开始解析每个元素时，调用的方法，会重复调用
55 */
56 @Override
57 public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
58
59 //qName 元素标签
60 System.out.println("---------startElement-------" + qName);
61
62 // 处理属性
63 if(attributes != null )
64 {
65 for (int i = 0; i < attributes.getLength(); ++i)
66 {
67 String attrName = attributes.getQName(i);
68 String attrValue = attributes.getValue(i);
69 System.out.print("\t "+ attrName + "=" + attrValue);
70 }
71 }
72 System.out.println("");
73 }
74
75 @Override
76 public void endElement(String uri, String localName, String qName) throws SAXException {
77
78 System.out.println("---------endElement-------" + qName);
79 }
80
81 /**
82 * 解析到每个元素的内容时会调用此方法
83 */
84 @Override
85 public void characters(char[] ch, int start, int length) throws SAXException {
86 String content = new String(ch,start,length);
87 System.out.println("---------characters-------" + "content == "+ content);
88 }
89 }
控制台输出：
1 ---------startDocument------- 2 ---------startElement-------conpany 3 name=hd 4 ---------characters-------content == 5 6 ---------startElement-------department 7 name=department1 8 ---------characters-------content == 9 10 ---------startElement-------employee 11 name=employee1 id=1 12 ---------characters-------content == 123 13 ---------endElement-------employee 14 ---------characters-------content == 15 16 ---------endElement-------department 17 ---------characters-------content == 18 19 ---------startElement-------department 20 name=department2 21 ---------characters-------content == 22 23 ---------startElement-------employee 24 name=employee2 id=2 25 ---------characters-------content == 321 26 ---------endElement-------employee 27 ---------characters-------content == 28 29 ---------startElement-------employee 30 name=employee3 id=3 31 ---------endElement-------employee 32 ---------characters-------content == 33 34 ---------endElement-------department 35 ---------characters-------content == 36 37 ---------startElement-------department 38 name=department3 39 ---------characters-------content == 40 41 ---------endElement-------department 42 ---------characters-------content == 43 44 ---------endElement-------conpany 45 ---------endDocument-------
时间： 2024-10-01 05:07:42