java解析XML映射成對象實體

 

1.創建一個XML文件：config.xml

<?xml version="1.0" encoding="utf-8"?>
<root >

    <school name="第一初級中學" description="學校信息">
        <grade name="九年級" description="年級信息" >
            <classes name="一班" description="班級信息" master="張非" studentCount="40" />
            <classes name="二班" description="班級信息" master="李虧" studentCount="38" />
            <classes name="三班" description="班級信息" master="關雨" studentCount="39" />
            <classes name="四班" description="班級信息" master="趙芸" studentCount="41" />
        </grade>
    </school>

    <school name="第二初級中學" description="學校信息">
        <grade name="九年級" description="年級信息" >
            <classes name="一班" description="班級信息" master="張非" studentCount="40" />
            <classes name="二班" description="班級信息" master="李虧" studentCount="38" />
            <classes name="三班" description="班級信息" master="關雨" studentCount="39" />
            <classes name="四班" description="班級信息" master="趙芸" studentCount="41" />
        </grade>
    </school>

</root>

 

2.寫一個解析工具類:XMLUtil.java

package org.example.util;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import java.io.*;

/**
 * 將XML轉換成Object
 */
public class XMLUtil {

    /**
     * 將String類型的xml轉換成對象
     */
    public static Object convertXmlStrToObject(Class<?> clazz, String xmlStr) {
        Object xmlObject = null;
        try {
            JAXBContext context = JAXBContext.newInstance(clazz);
            // 進行將Xml轉成對象的核心接口
            Unmarshaller unmarshal = context.createUnmarshaller();
            StringReader sr = new StringReader(xmlStr);
            xmlObject = unmarshal.unmarshal(sr);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return xmlObject;
    }

    /**
     * 將file類型的xml轉換成對象
     */
    public static Object convertXmlFileToObject(Class<?> clazz, String xmlPath) {
        Object xmlObject = null;
        try {
            JAXBContext context = JAXBContext.newInstance(clazz);
            Unmarshaller unmarshaller = context.createUnmarshaller();
            InputStreamReader isr=new InputStreamReader(new FileInputStream(xmlPath),"UTF-8");
            xmlObject = unmarshaller.unmarshal(isr);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return xmlObject;
    }

}

 

3.按照XML結構，寫出將要映射的實體類：

　　1）Root.java

package org.example.entity;

import lombok.Data;

import javax.xml.bind.annotation.XmlRootElement;
import java.util.List;

@Data
//注解用於標記當前類是XML的根節點，name值為根節點名
@XmlRootElement(name = "root")
public class Root {

    /**
     * 注意：屬性名稱要跟xml節點名統一
     */
    private List<School> school;

}

　　2）School.java

package org.example.entity;

import lombok.Setter;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlTransient;
import java.util.List;

@Setter
public class School {

    /**
     *  注解 @XmlAttribute 表示該屬性是XML節點的屬性
     */
    @XmlAttribute
    private String name;
    @XmlAttribute
    private String description;


    private List<Grade> grade;

    /**
     * @XmlTransient 注解解決 JavaBean 屬性名稱與字段名稱之間的名稱沖突
     * @return
     */
    @XmlTransient
    public String getName() {
        return name;
    }

    @XmlTransient
    public String getDescription() {
        return description;
    }

    public List<Grade> getGrade() {
        return grade;
    }

    @Override
    public String toString() {
        return "School{" +
                "name='" + name + '\'' +
                ", description='" + description + '\'' +
                ", grade=" + grade +
                '}';
    }
}

 

　　3）Grade.java

package org.example.entity;

import lombok.Setter;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlTransient;
import java.util.List;

@Setter
public class Grade {

    @XmlAttribute
    private String name;
    @XmlAttribute
    private String description;

    private List<Classes> classes;

    @XmlTransient
    public String getName() {
        return name;
    }

    @XmlTransient
    public String getDescription() {
        return description;
    }

    public List<Classes> getClasses() {
        return classes;
    }

    @Override
    public String toString() {
        return "Grade{" +
                "name='" + name + '\'' +
                ", description='" + description + '\'' +
                ", classes=" + classes +
                '}';
    }
}

 

　　4）Classes.java

package org.example.entity;

import lombok.Setter;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlTransient;

@Setter
public class Classes {

    @XmlAttribute
    private String name;
    @XmlAttribute
    private String master;
    @XmlAttribute
    private String description;
    @XmlAttribute
    private Integer studentCount;

    @XmlTransient
    public String getName() {
        return name;
    }

    @XmlTransient
    public String getMaster() {
        return master;
    }

    @XmlTransient
    public Integer getStudentCount() {
        return studentCount;
    }

    @XmlTransient
    public String getDescription() {
        return description;
    }

    @Override
    public String toString() {
        return "Classes{" +
                "name='" + name + '\'' +
                ", master='" + master + '\'' +
                ", description='" + description + '\'' +
                ", studentCount=" + studentCount +
                '}';
    }
}

 

4.編寫一個測試類

package org.example;

import org.example.entity.Root;
import org.example.util.XMLUtil;

public class Test {

    public static void main(String[] args) {

        String path = "config.xml";
        Root root = (Root) XMLUtil.convertXmlFileToObject(Root.class, path);
        System.out.println(root);

    }
}

 

5.文件結構

　　

 

 

 

 

附：lambok 引用

    <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.20</version>
      <scope>provided</scope>
    </dependency>