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
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<students>
<student>
<name sid="111">李四</name>
<age>23</age>
<gender>男</gender>
</student>
<student>
<name sid="222">张三</name>
<age>21</age>
<gender>女</gender>
</student>
</students>
2：测试主体部分
@Test
public void testParseXml() throws ParserConfigurationException,
SAXException, IOException {
// 1:获取解析器工厂
SAXParserFactory factory = SAXParserFactory.newInstance();
// 2:获取解析器
SAXParser parser = factory.newSAXParser();
// 3:获取读取器
XMLReader reader = parser.getXMLReader();
// 4:设置内容格式
reader.setContentHandler(new GetSecondNameHandler());
// 5:解析文件
reader.parse("xml/exam.xml");
}
a:获取整个xml文档标签的处理事件
// 定义一个解析全文的解析器
class MyHandler implements ContentHandler { @Override
public void setDocumentLocator(Locator locator) { } @Override
public void startDocument() throws SAXException { } @Override
public void endDocument() throws SAXException { } @Override
public void startPrefixMapping(String prefix, String uri)
throws SAXException { } @Override
public void endPrefixMapping(String prefix) throws SAXException { } @Override
public void startElement(String uri, String localName, String qName,
Attributes atts) throws SAXException {
System.out.println("<" + qName + ">");
// 获取元素的属性
for (int i = 0; i < atts.getLength(); i++) {
String attrName = atts.getQName(i);
String attrValue = atts.getValue(i);
System.out.println(attrName + "=" + attrValue);
}
} @Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
System.out.println("<" + qName + "/>");
} @Override
public void characters(char[] ch, int start, int length)
throws SAXException {
System.out.println(new String(ch, start, length));
} @Override
public void ignorableWhitespace(char[] ch, int start, int length)
throws SAXException { } @Override
public void processingInstruction(String target, String data)
throws SAXException { } @Override
public void skippedEntity(String name) throws SAXException { } }
b：定义“获取指定内容,获取第二个学生的名字”事件
class GetSecondNameHandler extends DefaultHandler {
private String contentTag;
private int currentTag = 0;
private int getTag = 2;
@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
contentTag = qName;
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
contentTag = null;
}
@Override
public 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));
}
}
}
}
c:将xml信息封装成javabean对象，然后放到list集合中
/ 将xml中student元素内容封装成对象，然后放到list集合中
class BeanListHandler extends DefaultHandler {
private List<Student> list = new ArrayList<Student>();
private String tagName;
private Student stu; @Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
tagName = qName;
if ("student".equals(tagName)) {
stu = new Student();
}
} @Override
public void characters(char[] ch, int start, int length)
throws SAXException { if ("name".equals(tagName)) {
stu.setName(new String(ch, start, length));
}
if ("age".equals(tagName)) {
stu.setAge(Integer.parseInt(new String(ch, start, length)));
}
if ("gender".equals(tagName)) {
stu.setGender(new String(ch, start, length));
} } @Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
if ("student".equals(qName)) {
list.add(stu);
stu = null;
} tagName = null;
} public List<Student> getStudents() {
return list;
} }
测试程序代码修改为：
@Test
public void testParseXml() throws ParserConfigurationException,
SAXException, IOException {
// 1:获取解析器工厂
SAXParserFactory factory = SAXParserFactory.newInstance();
// 2:获取解析器
SAXParser parser = factory.newSAXParser();
// 3:获取读取器
XMLReader reader = parser.getXMLReader();
// 4:设置内容格式
BeanListHandler beanListHandler = new BeanListHandler();
reader.setContentHandler(beanListHandler);
// 5:解析文件
reader.parse("xml/exam.xml"); List<Student> list = beanListHandler.getStudents();
for (Student stu : list) {
System.out.println("name=" + stu.getName() + " age=" + stu.getAge()
+ " gender=" + stu.getGender());
}
}