javaweb学习总结十二(JAXP对XML文档进行SAX解析)

Posted 2020-08-08

一：JAXP使用SAX方式解析XML文件

1：dom解析与sax解析异同点

2：sax解析特点

 

二：代码案例

1：xml文件

 1 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 2 <students>
 3     <student>
 4         <name sid="111">李四</name>
 5         <age>23</age>
 6         <gender>男</gender>
 7     </student>
 8     <student>
 9         <name sid="222">张三</name>
10         <age>21</age>
11         <gender>女</gender>
12     </student>
13 </students>

2：测试主体部分

 1 @Test
 2     public void testParseXml() throws ParserConfigurationException,
 3             SAXException, IOException {
 4         // 1:获取解析器工厂
 5         SAXParserFactory factory = SAXParserFactory.newInstance();
 6         // 2:获取解析器
 7         SAXParser parser = factory.newSAXParser();
 8         // 3:获取读取器
 9         XMLReader reader = parser.getXMLReader();
10         // 4:设置内容格式
11         reader.setContentHandler(new GetSecondNameHandler());
12         // 5:解析文件
13         reader.parse("xml/exam.xml");
14     }

a:获取整个xml文档标签的处理事件

 1 // 定义一个解析全文的解析器
 2 class MyHandler implements ContentHandler {
 3 
 4     @Override
 5     public void setDocumentLocator(Locator locator) {
 6 
 7     }
 8 
 9     @Override
10     public void startDocument() throws SAXException {
11 
12     }
13 
14     @Override
15     public void endDocument() throws SAXException {
16 
17     }
18 
19     @Override
20     public void startPrefixMapping(String prefix, String uri)
21             throws SAXException {
22 
23     }
24 
25     @Override
26     public void endPrefixMapping(String prefix) throws SAXException {
27 
28     }
29 
30     @Override
31     public void startElement(String uri, String localName, String qName,
32             Attributes atts) throws SAXException {
33         System.out.println("<" + qName + ">");
34         // 获取元素的属性
35         for (int i = 0; i < atts.getLength(); i++) {
36             String attrName = atts.getQName(i);
37             String attrValue = atts.getValue(i);
38             System.out.println(attrName + "=" + attrValue);
39         }
40     }
41 
42     @Override
43     public void endElement(String uri, String localName, String qName)
44             throws SAXException {
45         System.out.println("<" + qName + "/>");
46     }
47 
48     @Override
49     public void characters(char[] ch, int start, int length)
50             throws SAXException {
51         System.out.println(new String(ch, start, length));
52     }
53 
54     @Override
55     public void ignorableWhitespace(char[] ch, int start, int length)
56             throws SAXException {
57 
58     }
59 
60     @Override
61     public void processingInstruction(String target, String data)
62             throws SAXException {
63 
64     }
65 
66     @Override
67     public void skippedEntity(String name) throws SAXException {
68 
69     }
70 
71 }

b：定义“获取指定内容,获取第二个学生的名字”事件

 1 class GetSecondNameHandler extends DefaultHandler {
 2 
 3     private String contentTag;
 4     private int currentTag = 0;
 5     private int getTag = 2;
 6 
 7     @Override
 8     public void startElement(String uri, String localName, String qName,
 9             Attributes attributes) throws SAXException {
10         contentTag = qName;
11     }
12 
13     @Override
14     public void endElement(String uri, String localName, String qName)
15             throws SAXException {
16         contentTag = null;
17     }
18 
19     @Override
20     public void characters(char[] ch, int start, int length)
21             throws SAXException {
22         if ("name".equals(contentTag)) {
23             currentTag++;
24             if (currentTag == getTag) {
25                 System.out.println(new String(ch, start, length));
26             }
27             
28         }
29     }
30 
31 }

 

 

 

class GetSecondNameHandler extends DefaultHandler {
private String contentTag;private int currentTag = 0;private int getTag = 2;
@Overridepublic void startElement(String uri, String localName, String qName,Attributes attributes) throws SAXException {contentTag = qName;}
@Overridepublic void endElement(String uri, String localName, String qName)throws SAXException {contentTag = null;}
@Overridepublic void characters(char[] ch, int start, int length)throws SAXException {if ("name".equals(contentTag)) {currentTag++;if (currentTag == getTag) {System.out.println(new String(ch, start, length));}}}
}