XML解析

目录

一.DOM

2.XPath方式

3.dom4j

1.引入依赖

2.application.xml

3.BeanDefine.java

一.DOM

studentx.xml

<?xml version="1.0"?> 
<students> 
  <student> 
    <name>John</name> 
    <grade>B</grade> 
    <age>12</age> 
  </student> 
  <student> 
    <name>Mary</name> 
    <grade>A</grade> 
    <age>11</age> 
  </student> 
  <student> 
    <name>Simon</name> 
    <grade>A</grade> 
    <age>18</age> 
  </student> 
</students>

XMLParser.java

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.Node;  
import org.w3c.dom.NodeList;  
public class XMLParser {
    public void getAllUserNames(String fileName) {  
        try {
            //1.获得一个文档解析器工厂：定义工厂API,使应用程序能够从XML文档获取生成DOM对象树的解析器
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();  
            //2.获得一个文档解析器：定义从XML文档获取DOM文档实例的API。 使用这个类，应用程序员可以从XML获得一个Document 。
            DocumentBuilder db = dbf.newDocumentBuilder();  
            File file = new File(fileName);  
            if (file.exists()) {  
                //3.解析器解析xmL文件，获得一个DOM文档
                Document doc = db.parse(file);  
                //4.通过DOM文档获取根结点元素，并打印
                Element docEle = doc.getDocumentElement();  
                System.out.println("Root element of the document: "+ docEle.getNodeName());  
                //5.通过DOM文档根据标签名获取所有其对应的结点，并将其存储在NodeList抽象集合中
                NodeList studentList = docEle.getElementsByTagName("student");  
                System.out.println("Total students: " + studentList.getLength());  
                //6.打印"student"结点下所有的结点信息
                if(studentList != null && studentList.getLength() > 0) {  
                    for(int i = 0; i < studentList.getLength(); i++) {  
                        //7.遍历一个"student"结点
                        Node node = studentList.item(i);  
                        //8.node.getNodeType() == Node.ELEMENT_NODE，表示node结点是一个Element(一组)
                        if(node.getNodeType() == Node.ELEMENT_NODE) {  
                            System.out.println("=====================");  
                            Element e = (Element) node;  
                            NodeList nodeList = e.getElementsByTagName("name");  
                            System.out.println("Name: "+ nodeList.item(0).getChildNodes().item(0).getNodeValue());  
                            nodeList = e.getElementsByTagName("grade");
                            System.out.println("Grade: "+nodeList.item(0).getChildNodes().item(0)  .getNodeValue());  
                            nodeList = e.getElementsByTagName("age");  
                            System.out.println("Age: "+ nodeList.item(0).getChildNodes().item(0).getNodeValue());  
                        }
                    }  
                }
            }
        } catch (Exception e) {  
            System.out.println(e);  
        }  
    }  
    public static void main(String[] args) {  
        XMLParser parser = new XMLParser();  
        parser.getAllUserNames("./src/students.xml");  
    }  
}

2.XPath方式

users.xml

<?xml version="1.0"?> 
<users>
    <user id="1">
        <name>张三</name>
        <createTime>2018-10-15</createTime>
        <password>123</password>
        <phone>10086</phone>
        <nickName>阿毛</nickName>
    </user>
    <user id="2">
        <name>李四</name>
        <createTime>2018-10-15</createTime>
        <password>234</password>
        <phone>12306</phone>
        <nickName>二狗子</nickName>
    </user>
</users>
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class UserEntity {
    private Long id;
    private String name;
    private Date createTime;
    private String password;
    private String phone;
    private String nickName;
    static UserEntity buildUserEntity(String id, String name, String createTime, String password, String phone,
            String nickName) throws ParseException {
        UserEntity user=new UserEntity();
        user.id=Long.valueOf(id);
        user.name=name;
        user.createTime=new SimpleDateFormat("yyyy-MM-dd").parse(createTime);
        user.password=password;
        user.nickName=nickName;
        return user;
    }
    @Override
    public String toString() {
        // TODO Auto-generated method stub
        return id+"-"+name+"-"+createTime+"-"+password+"-"+nickName;
    }
}
import java.io.File;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;  
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;  
import org.w3c.dom.Element;  
import org.w3c.dom.Node;  
import org.w3c.dom.NodeList;  
public class XMLParser {  
  public void getAllUserNames(String fileName) {  
    try {
      //1.获得一个文档解析器工厂：定义工厂API,使应用程序能够从XML文档获取生成DOM对象树的解析器
      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();  
      //2.获得一个文档解析器：定义从XML文档获取DOM文档实例的API。 使用这个类，应用程序员可以从XML获得一个Document 。
      DocumentBuilder builder = dbf.newDocumentBuilder();  
      File file=new File(fileName);
      //3.通过解析器解析xml文件，获得一个文档对象
      Document document=builder.parse(file);
      //4.获取新的XPathFactory实例
      XPathFactory xpathFactory=XPathFactory.newInstance();
      //5.一个XPathFactory实例可以用来创建XPath对象
      XPath xpath=xpathFactory.newXPath();
      //6.xpath根据根结点"users"标签解析document文档
      NodeList nodeList=(NodeList) xpath.evaluate("/users/*", document,XPathConstants.NODESET);
      //7.获取一个ArrayList实例用来存储UserEntity对象
      List<UserEntity> userList=new ArrayList<UserEntity>();
      //8.获取所有的user结点
      for(int i=1;i<nodeList.getLength()+1;i++) {
        String path="/users/user["+i+"]";
        String id=(String) xpath.evaluate(path+"/@id", document,XPathConstants.STRING);
        String name=(String) xpath.evaluate(path+"/name", document,XPathConstants.STRING);
        String createTime=(String) xpath.evaluate(path+"/createTime", document,XPathConstants.STRING);
        String password=(String) xpath.evaluate(path+"/password", document,XPathConstants.STRING);
        String phone=(String) xpath.evaluate(path+"/phone", document,XPathConstants.STRING);
        String nickName=(String) xpath.evaluate(path+"/nickName", document,XPathConstants.STRING);
        //调用buildUserEntity()方法构建UserEntity对象
        UserEntity userEntity=UserEntity.buildUserEntity(id,name,createTime,password,phone,nickName);
        userList.add(userEntity);
      }
      for(UserEntity user:userList) {
          System.out.println(user);
      }
    }catch(Exception e){
        e.getMessage();
    }
  }  
    public static void main(String[] args) {  
        XMLParser parser = new XMLParser();  
        parser.getAllUserNames("./src/users.xml");  
    }  
}

3.dom4j

1.引入依赖

<!-- dom4j解析xml -->
    <dependency>
        <groupId>dom4j</groupId>
        <artifactId>dom4j</artifactId>
        <version>1.6.1</version>
    </dependency>

2.application.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans>
    <bean id="userDao" class="cn.yiguang.testProject.annotation.UserDaoImpl"></bean>
    <bean id="user1Dao" class="cn.yiguang.testProject.annotation.User1DaoImpl"></bean>
    <bean id="user2Dao" class="cn.yiguang.testProject.annotation.User2DaoImpl"></bean>
    <bean id="userService" class="cn.yiguang.testProject.annotation.UserServiceImpl"></bean>
</beans>

3.BeanDefine.java

public class BeanDefine {
    private String id;
    private String className;
    public BeanDefine(String id, String className) {
        this.id = id;
        this.className = className;
    }
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getClassName() {
        return className;
    }
    public void setClassName(String className) {
        this.className = className;
    }
    @Override
    public String toString() {
        return "id:"+id+",className:"+className;
    }
}

4.测试

import java.util.Iterator;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
public class Test {
    public static void main(String[] args) {
        // 读取xml文件,转换成Document结点
        Document document = null;
        // 创建一个SAXReader解析器
        SAXReader saxReader = new SAXReader();
        try {
            ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
            document = saxReader.read(classLoader.getResourceAsStream("configAnnotation.xml"));
            Element beans = document.getRootElement();
            for (Iterator<Element> beansList = beans.elementIterator();beansList.hasNext();) {
                Element element = beansList.next();
                BeanDefine bean = new BeanDefine(element.attributeValue("id"), element.attributeValue("class"));
                System.out.println(bean.toString());
            }
        }catch (DocumentException e){
            System.out.println("解析配置文件出错......");
        }
    }
}