详细介绍Xml数据解析的三种方式的示例代码

xml作为一种数据交互格式，涉及到xml数据的生成与解析，这里将讲述Xml解析的三种方式。

二、Dom解析

1、创建解析器工厂对象（DocumentBuilderFactory对象）

2、创建解析器对象（DocumentBuilder）

3、创建Document对象

例如解析下述文件

<?xml version="1.0" encoding="utf-8"?>  <students>            <student id = "1001">               <id>1</id>               <name>杨威</name>               <address>大连</address>               <age>21</age>          </student>            <student id = "1002">               <id>2</id>               <name>劉海洋</name>               <address>深圳</address>               <age>23</age>          </student>            <student id = "1003">               <id>3</id>               <name>王小波</name>               <address>廣州</address>               <age>22</age>          </student>    </students>

解析代码如下

[code]package com.kuxiao.train.xml;    import java.io.File;    import javax.xml.parsers.DocumentBuilder;  import javax.xml.parsers.DocumentBuilderFactory;    import org.w3c.dom.Document;  import org.w3c.dom.Element;  import org.w3c.dom.NodeList;    public class XmlParseTest {        public static void main(String[] args) throws Exception {            //xml doc解析步骤          //1、获取解析工厂对象          DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();          //2、构建解析器对象          DocumentBuilder   db = dbf.newDocumentBuilder();          //3、构建docment对象          Document  doc = db.parse(new File("person.xml"));            Element ele = doc.getDocumentElement();            //实现解析逻辑          NodeList list = doc.getElementsByTagName("student");            for(int i = 0; i < list.getLength();i++)          {                Element element = (Element) list.item(i);                String attrid = element.getAttribute("id");                System.out.println("attrid = " + attrid);                Element  element1 = (Element) element.getElementsByTagName("id").item(0);                String id = element1.getFirstChild().getNodeValue();                System.out.println(id);                element1 = (Element) element.getElementsByTagName("name").item(0);                String name = element1.getFirstChild().getNodeValue();                System.out.println(name);                element1 = (Element) element.getElementsByTagName("address").item(0);                String address = element1.getFirstChild().getNodeValue();                System.out.println(address);            }               }    }

三、注意事项

1、Element ele = doc.getDocumentElement(); 获取根元素

2、获取到元素时，元素的值也是节点，必须element.getFirstChild().getNodeValue()方法取值。

3、xml中的空白也是Node，text类型的。

四、SAX解析

1、创建SAXParserFactory对象

2、创建SAXparser对象

3、创建MyHandler继承DefaultHandler类，重写方法。

4、sp.parse(new File(“student.xml”), new MyHandler(list));

[code]package com.kuxiao.train.xml.sax;    import java.io.File;  import java.util.ArrayList;  import java.util.List;  import java.util.Stack;    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 TestSax {        public static void main(String[] args) throws Exception {            SAXParserFactory spf = SAXParserFactory.newInstance();          SAXParser sp = spf.newSAXParser();          List<Student> list = new ArrayList<>();          sp.parse(new File("student.xml"), new MyHandler(list));          System.out.println(list);        }  }    class MyHandler extends DefaultHandler {        private Stack<String> stack = new Stack<>();      private Student student;      private List<Student> mList = null;        public MyHandler(List<Student> list)      {            this.mList = list;      }      @Override      public void startDocument() throws SAXException {            System.out.println("解析文档开始了...");      }        @Override      public void startElement(String uri, String localName, String qName,              Attributes attributes) throws SAXException {              if(qName.equals("学生"))              {                  student = new Student();                  if(attributes.getLength() != 0)                  {                       for(int i = 0; i < attributes.getLength();i++)                       {                              String id = attributes.getValue(i);                              student.setId(Integer.parseInt(id));                       }                  }              }              /*if(qName.equals("姓名"))              {                   stack.push(qName);              }              if(qName.equals("年龄"))              {                   stack.push(qName);              }              if(qName.equals("性别"))              {                   stack.push(qName);              }*/              stack.push(qName);      }        @Override      public void characters(char[] ch, int start, int length)              throws SAXException {               String qName = stack.peek();              if(qName.equals("性别")){                  student.setGender(new String(ch,start,length));              }              if(qName.equals("姓名")){                  student.setName(new String(ch,start,length));              }              if(qName.equals("年龄")){                  student.setAge(new String(ch,start,length));              }      }        @Override      public void endElement(String uri, String localName, String qName)              throws SAXException {              stack.pop();              if(qName.equals("学生"))              {                  mList.add(student);                  student = null;              }      }        @Override      public void endDocument() throws SAXException {           System.out.println("解析文档结束了.....");      }    }

SAX是基于事件模型的，顺序解析的，内部实现是观察者模式，优势在于占用内存少，效率高，缺点在编码相对比较复杂。

五、Pull解析

1、此解析方式不是JDK自带的，需要导入第三方库

2、创建XmlPullParserFactory对象

3、创建XmlPullParser对象

4、调用xpp.setInput(is,”utf-8”)

5、对应事件类型处理 xpp.next()下一个事件类型

[code]package com.kuxiao.train.xml.pull;    import java.io.File;  import java.io.FileInputStream;  import java.io.InputStream;  import java.lang.reflect.Method;  import java.util.ArrayList;  import java.util.List;    import org.xmlpull.v1.XmlPullParser;  import org.xmlpull.v1.XmlPullParserFactory;    public class PullTest {        public static void main(String[] args) throws Exception {            FileInputStream is = new FileInputStream(new File("person.xml"));          long time = System.currentTimeMillis();          List<Student> list = new ArrayList<>();          XmlPullParserFactory xppf = XmlPullParserFactory.newInstance();          XmlPullParser xpp = xppf.newPullParser();            xpp.setInput(is, "utf-8");          Student student = null;          int eventType = xpp.getEventType();          while (eventType != XmlPullParser.END_DOCUMENT) {                switch (eventType) {              case XmlPullParser.START_TAG:                    if (xpp.getName().equals("student")) {                      student = new Student();                      String id = xpp.getAttributeValue(0);                      student.setId(id);                  } else if (xpp.getName().equals("name")) {                      student.setName(xpp.nextText());                    } else if (xpp.getName().equals("address")) {                      student.setAddress(xpp.nextText());                  } else if (xpp.getName().equals("age")) {                      student.setAge(xpp.nextText());                  }                  break;              case XmlPullParser.START_DOCUMENT:                  System.out.println("开始了....");                  break;              case XmlPullParser.END_TAG:                  if (xpp.getName().equals("student")) {                      list.add(student);                      student = null;                  }                  break;              }              eventType = xpp.next();          }            is.close();          long time1 = System.currentTimeMillis();          System.out.println(time1 - time);          for (Student student2 : list) {              System.out.println(student2);          }            FileInputStream fis = new FileInputStream(new File("person.xml"));          List<Student> list1 = getListBean(fis, new String[] { "id", "name",                  "address", "age", "gender" }, Student.class, 0);          for (Student student2 : list1) {              System.out.println(student2);          }        }     //封装的全能解析xml文件的方法      //参数说明     //attrs是文件里bean对象的元素与属性名     //clazz是Bean对象的class对象     //j代表属性的个数      public static <T> List<T> getListBean(InputStream is, String[] attrs,              Class<T> clazz, int j) throws Exception {          long time = System.currentTimeMillis();          T c = null;          XmlPullParserFactory xppf = XmlPullParserFactory.newInstance();          XmlPullParser xpp = xppf.newPullParser();          xpp.setInput(is, "utf-8");          List<T> list = null;          int eventType = xpp.getEventType();          String classname = "";            while (eventType != XmlPullParser.END_DOCUMENT) {              switch (eventType) {              case XmlPullParser.START_TAG:                  int bigen = clazz.getName().lastIndexOf(".") + 1;                  classname = clazz.getName().substring(bigen);                  classname = classname.substring(0, 1).toLowerCase()                          + classname.substring(1);                  String elementName = xpp.getName();                    if (classname.equals(elementName)) {                        c = clazz.newInstance();                      if (xpp.getAttributeCount() != 0) {                          for (int i = 0; i < j; i++) {                              String attrName = xpp.getAttributeName(i);                              for (String field : attrs) {                                    if (field.equals(attrName)) {                                      String frist = field.substring(0, 1)                                              .toUpperCase();                                      Method method = clazz.getDeclaredMethod(                                              "set" + frist + field.substring(1),                                              new Class[] { String.class });                                      method.setAccessible(true);                                      method.invoke(c, xpp.getAttributeValue(i));                                  }                                }                          }                      }                    } else {                      for (String field : attrs) {                            if (field.equals(elementName)) {                                String frist = field.substring(0, 1).toUpperCase();                              Method method = clazz.getDeclaredMethod("set"                                      + frist + field.substring(1),                                      new Class[] { String.class });                              method.setAccessible(true);                              method.invoke(c, xpp.nextText());                          }                        }                  }                    break;              case XmlPullParser.START_DOCUMENT:                  list = new ArrayList<T>();                  break;                case XmlPullParser.END_TAG:                  if (!classname.equals("") && classname.equals(xpp.getName())) {                      list.add(c);                      c = null;                  }                  break;              }              eventType = xpp.next();          }          is.close();          long time1 = System.currentTimeMillis();          System.out.println(time1 - time);          return list;      }    }

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