使用JAXB将xml转成Java对象

工作中遇到个问题，需要将xml转对象，之前复杂的xml都是自己用dom4j来解析组装成Java对象，但是对于简单的，看到了JAXB处理的这种方式，就整理下，写成个工具类。

1. xml内容

city.xml

<?xml version="1.0" encoding="UTF-8" ?>
<c c1="0"><a>10</a><b>20</b><d d1="101280101" d2="重庆" d3="nanping" d4="南坪"/><d d1="101280102" d2="重庆" d3="yubei" d4="渝北"/><d d1="101280103" d2="重庆" d3="dadukou" d4="大渡口"/>
</c>

2. Java对象类

• CityList.xml

package com.stormkai.jaxb;import lombok.Data;
import javax.xml.bind.annotation.*;
import java.util.List;@Data
@XmlRootElement(name = "c")
@XmlAccessorType(XmlAccessType.FIELD)
public class CityList {@XmlAttribute(name = "c1")private String c1;@XmlElement(name = "a")private String a;@XmlElement(name = "b")private String b;@XmlElement(name = "d")private List<City> cityList;
}

• City.java

package com.stormkai.jaxb;import lombok.Data;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlRootElement;@Data
@XmlRootElement(name = "d")
@XmlAccessorType(XmlAccessType.FIELD)
public class City {@XmlAttribute(name = "d1")private String cityId;@XmlAttribute(name = "d2")private String cityName;@XmlAttribute(name = "d3")private String cityNode;@XmlAttribute(name = "d4")private String area;
}

JAXBContext类，是应用的入口，用于管理XML/Java绑定信息
Unmarshaller接口，将XML数据反序列化为Java对象
@XmlType，将Java类或枚举类型映射到XML模式类型
@XmlAccessorType(XmlAccessType.FIELD) ，控制字段或属性的序列化

• PUBLIC_MEMBER ：默认值，public权限亦或是具有get/set方法属性
• FIELD：对象中的所有属性
• PROPERT：对象中所有具备get/set方法的属性
• NONE：对象的所有属性都不映射

@XmlAccessorOrder，控制JAXB 绑定类中属性和字段的排序
@XmlJavaTypeAdapter，使用定制的适配器（即扩展抽象类XmlAdapter并覆盖marshal()和unmarshal()方法），以序列化Java类为XML
@XmlElementWrapper ，对于数组或集合（即包含多个元素的成员变量），生成一个包装该数组或集合的XML元素（称为包装器）
@XmlRootElement，将Java类或枚举类型映射到XML元素
@XmlElement，将Java类的一个属性映射到与属性同名的一个XML元素
@XmlAttribute，将Java类的一个属性映射到与属性同名的一个XML属性

3. 封装的工具类

XmlBuilder.java

package com.stormkai.jaxb;import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import java.io.Reader;
import java.io.StringReader;public class XmlBuilder {public static <T> T xmlToObj4Jaxb(Class<?> clazz, String xml){try {T xmlObject;Reader reader;JAXBContext context = JAXBContext.newInstance(clazz);Unmarshaller unmarshaller = context.createUnmarshaller();reader = new StringReader(xml);xmlObject = (T)unmarshaller.unmarshal(reader);reader.close();return xmlObject;} catch (Exception e) {e.printStackTrace();}return null;}
}

4. 测试

public class XmlBuilder {public static <T> T xmlToObj4Jaxb(Class<?> clazz, String xml){try {T xmlObject;Reader reader;JAXBContext context = JAXBContext.newInstance(clazz);Unmarshaller unmarshaller = context.createUnmarshaller();reader = new StringReader(xml);xmlObject = (T)unmarshaller.unmarshal(reader);reader.close();return xmlObject;} catch (Exception e) {e.printStackTrace();}return null;}public String getCityXml1(){String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n" +"<c c1=\"0\">\n" +"    <a>10</a>\n" +"    <b>20</b>\n" +"    <d d1=\"101280101\" d2=\"重庆\" d3=\"nanping\" d4=\"南坪\"/>\n" +"    <d d1=\"101280102\" d2=\"重庆\" d3=\"yubei\" d4=\"渝北\"/>\n" +"    <d d1=\"101280103\" d2=\"重庆\" d3=\"dadukou\" d4=\"大渡口\"/>\n" +"</c>";return xml;}public static void main(String[] args) {String xml = new XmlBuilder().getCityXml1();CityList cityList = xmlToObj4Jaxb(CityList.class, xml);System.out.println(JSON.toJSONString(cityList));}
}

输出结果:

{"a":"10","b":"20","c1":"0","cityList":[{"area":"南坪","cityId":"101280101","cityName":"重庆","cityNode":"nanping"},{"area":"渝北","cityId":"101280102","cityName":"重庆","cityNode":"yubei"},{"area":"大渡口","cityId":"101280103","cityName":"重庆","cityNode":"dadukou"}]}Process finished with exit code 0

输出的json格式化后:

{"a": "10","b": "20","c1": "0","cityList": [{"area": "南坪","cityId": "101280101","cityName": "重庆","cityNode": "nanping"}, {"area": "渝北","cityId": "101280102","cityName": "重庆","cityNode": "yubei"}, {"area": "大渡口","cityId": "101280103","cityName": "重庆","cityNode": "dadukou"}]
}