Java StAX API提供了两个XML处理API –基于游标和基于迭代器。
前面我们看到了基于迭代器的API的示例，该API可以读取XML文件和写入XML文件。
其中我们将学习如何使用基于游标的API来读取XML文件。

当我们使用StAX XML Parser时，我们需要创建XMLInputFactory来读取XML文件。
然后我们可以通过创建XMLStreamReader对象来读取文件来选择基于游标的API。
XMLStreamReader next()方法用于获取下一个解析事件，并根据事件类型返回int值。
常见事件类型是"开始文档"，"开始元素"，"字符"，"结束元素"和"结束文档"。
XMLStreamConstants包含int常量，可用于根据其类型处理事件。

对于本教程，我们在下面的xml文件中列出了Employee元素。

<?xml version="1.0" encoding="UTF-8"?>
<Employees>
	<Employee id="1">
		<age>29</age>
		<name>hyman</name>
		<gender>Male</gender>
		<role>Java Developer</role>
	</Employee>
	<Employee id="2">
		<age>35</age>
		<name>Lisa</name>
		<gender>Female</gender>
		<role>CEO</role>
	</Employee>
	<Employee id="3">
		<age>40</age>
		<name>Tom</name>
		<gender>Male</gender>
		<role>Manager</role>
	</Employee>
	<Employee id="4">
		<age>25</age>
		<name>Meghna</name>
		<gender>Female</gender>
		<role>Manager</role>
	</Employee>
</Employees>

我们有Employee类来表示Employee元素。

package com.theitroad.xml;

public class Employee {
  private int id;
  private String name;
  private String gender;
  private int age;
  private String role;
  
  public int getId() {
      return id;
  }
  public void setId(int id) {
      this.id = id;
  }
  public String getName() {
      return name;
  }
  public void setName(String name) {
      this.name = name;
  }
  public String getGender() {
      return gender;
  }
  public void setGender(String gender) {
      this.gender = gender;
  }
  public int getAge() {
      return age;
  }
  public void setAge(int age) {
      this.age = age;
  }
  public String getRole() {
      return role;
  }
  public void setRole(String role) {
      this.role = role;
  }
  
  @Override
  public String toString() {
      return "Employee:: ID="+this.id+" Name=" + this.name + " Age=" + this.age + " Gender=" + this.gender +
              " Role=" + this.role;
  }
  
}

这是我们使用StAX XMLStreamReader读取xml文件到Employee对象列表的类。

package com.theitroad.xml.stax;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import com.theitroad.xml.Employee;

public class StaxXMLStreamReader {
  
  private static boolean bName;
  private static boolean bAge;
  private static boolean bGender;
  private static boolean bRole;

  public static void main(String[] args) {
      String fileName = "/Users/hyman/employees.xml";
      List<Employee> empList = parseXML(fileName);
      for(Employee emp : empList){
          System.out.println(emp.toString());
      }
  }

  private static List<Employee> parseXML(String fileName) {
      List<Employee> empList = new ArrayList<>();
      Employee emp = null;
      XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance();
      try {
          XMLStreamReader xmlStreamReader = xmlInputFactory.createXMLStreamReader(new FileInputStream(fileName));
          int event = xmlStreamReader.getEventType();
          while(true){
              switch(event) {
              case XMLStreamConstants.START_ELEMENT:
                  if(xmlStreamReader.getLocalName().equals("Employee")){
                      emp = new Employee();
                      emp.setId(Integer.parseInt(xmlStreamReader.getAttributeValue(0)));
                  }else if(xmlStreamReader.getLocalName().equals("name")){
                      bName=true;
                  }else if(xmlStreamReader.getLocalName().equals("age")){
                      bAge=true;
                  }else if(xmlStreamReader.getLocalName().equals("role")){
                      bRole=true;
                  }else if(xmlStreamReader.getLocalName().equals("gender")){
                      bGender=true;
                  }
                  break;
              case XMLStreamConstants.CHARACTERS:
                  if(bName){
                      emp.setName(xmlStreamReader.getText());
                      bName=false;
                  }else if(bAge){
                      emp.setAge(Integer.parseInt(xmlStreamReader.getText()));
                      bAge=false;
                  }else if(bGender){
                      emp.setGender(xmlStreamReader.getText());
                      bGender=false;
                  }else if(bRole){
                      emp.setRole(xmlStreamReader.getText());
                      bRole=false;
                  }
                  break;
              case XMLStreamConstants.END_ELEMENT:
                  if(xmlStreamReader.getLocalName().equals("Employee")){
                      empList.add(emp);
                  }
                  break;
              }
              if (!xmlStreamReader.hasNext())
                  break;

            event = xmlStreamReader.next();
          }
          
      } catch (FileNotFoundException | XMLStreamException e) {
          e.printStackTrace();
      }
      return empList;
  }
}

当我们执行上面的程序时，我们在控制台中得到以下输出。

Employee:: ID=1 Name=hyman Age=29 Gender=Male Role=Java Developer
Employee:: ID=2 Name=Lisa Age=35 Gender=Female Role=CEO
Employee:: ID=3 Name=Tom Age=40 Gender=Male Role=Manager
Employee:: ID=4 Name=Meghna Age=25 Gender=Female Role=Manager