javax.xml 实现对象序列化与返序列化

目录结构：

根标签实体类Domain

package com.yh.xml;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "Domain")//如果不指定name 则标签名称默认使用类名+首字母小写。
@XmlAccessorType(XmlAccessType.FIELD) //支持XmlAttribute，XmlElement注解在 字段上，否则 XmlElement需要注解在get方法上
public class Domain {
    @XmlAttribute  //xml 属性注解，Domain标签的属性
    private String type;
    private String os;//简单字段
    @XmlElement(name = "D") //指定标签名称，默认是属性名<d>。如果不用属性名，可以用此注解指定
    private D d;//复合字段

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getOs() {
        return os;
    }

    public void setOs(String os) {
        this.os = os;
    }

    public D getD() {
        return d;
    }

    public void setD(D d) {
        this.d = d;
    }

    @Override
    public String toString() {
        return "Domain{" +
                "type="" + type + """ +
                ", os="" + os + """ +
                ", d=" + d +
                "}";
    }
}

/**
 * 根标签下的复合子节点
 */
class D {
    private String param1;
    private String param2;

    public String getParam1() {
        return param1;
    }

    public void setParam1(String param1) {
        this.param1 = param1;
    }

    public String getParam2() {
        return param2;
    }

    public void setParam2(String param2) {
        this.param2 = param2;
    }

    @Override
    public String toString() {
        return "D{" +
                "param1="" + param1 + """ +
                ", param2="" + param2 + """ +
                "}";
    }
}

 package-info.java //命名空间设置（xmlns=”http://www.baidu.com”），本类放到实体类同层包内

//命名空间
@XmlSchema(namespace="http://www.baidu.com", elementFormDefault = XmlNsForm.QUALIFIED)
package com.yh.xml;
import javax.xml.bind.annotation.XmlNsForm;
import javax.xml.bind.annotation.XmlSchema;

demo 入口类XmlDemo：

package com.yh.xml;

import javax.xml.bind.Unmarshaller;
import javax.xml.bind.annotation.XmlNs;
import javax.xml.bind.annotation.XmlSchema;


import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.transform.stream.StreamResult;
import java.io.StringReader;
import java.io.StringWriter;

public class XmlDemo {

    public static void main(String[] args) throws JAXBException {
        JAXBContext jc = JAXBContext.newInstance(Domain.class);
        //复合对象
        Domain domain = new Domain();//ROOT标签
        D d = new D();//子标签-复合标签
        d.setParam1("p1");
        d.setParam2("p2");

        domain.setType("kvm");//ROOT标签的属性
        domain.setOs("linux");//子标签-简单类型标签
        domain.setD(d);

        /*Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(domain, System.out);//输出到控制台*/
        System.out.println("=======序列化=======");
        String marshal = marshal(domain.getClass(), domain);
        System.out.println(marshal);
        System.out.println("=======反序列化=======");
        Domain domain1 = unmarshal(marshal, Domain.class);
        System.out.println(domain1);
    }


    /**
     * 把xml配置转换成对象
     *
     * @param xml
     * @param classObj
     * @return
     */

    public static <T> T unmarshal(String xml, Class<T> classObj) {
        T obj;
        try {
            JAXBContext jaxbContext = JAXBContext.newInstance(classObj);
            Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
            obj = (T) unmarshaller.unmarshal(new StringReader(xml));
            return obj;
        } catch (JAXBException e) {
            e.printStackTrace();
        }
        return null;
    }


    /**
     * 把对象转换成xml配置
     *
     * @param classObj
     * @param obj
     * @return
     */

    public static String marshal(Class<?> classObj, Object obj) {
        String xmlStr = "";
        try {
            JAXBContext jaxbContext = JAXBContext.newInstance(classObj);
            Marshaller marshaller = jaxbContext.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");// //编码格式
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);// 是否格式化生成的xml串
            //marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);// 是否省略xm头声明信息
            StringWriter out = new StringWriter();
            marshaller.marshal(obj, new StreamResult(out));
            xmlStr = out.toString();
        } catch (JAXBException e) {
            e.printStackTrace();
        }
        return xmlStr;
    }

}

执行结果：