使用JAXB将xml转成Java对象

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

<c c1="0">
    <a>10a>
    <b>20b>
    <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>
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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;
}

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• 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;
}

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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;
    }
}

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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 = "\n" +
                "\n" +
                "    10\n" +
                "    20\n" +
                "    \n" +
                "    \n" +
                "    \n" +
                "";
        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));
    }
}

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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
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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"
	}]
}
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