JavaBean与xml互转的方法详解

2年前 (2022) 程序员胖胖胖虎阿

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一、简介

JAXB（Java Architecture for XML Binding) 是一个业界的标准，是一项可以根据XML Schema产生Java类的技术。该过程中，JAXB也提供了将XML实例文档反向生成Java对象树的方法，并能将Java对象树的内容重新写到 XML实例文档。

Jaxb 2.0是JDK 1.6的组成部分。我们不需要下载第三方jar包即可做到轻松转换。Jaxb2使用了JDK的新特性，如：Annotation、GenericType等，需要在即将转换的JavaBean中添加annotation注解。

二、重要概念

JAXBContext类，是应用的入口，用于管理XML/Java绑定信息。

Marshaller接口，将Java对象序列化为XML数据。

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。FIELD表示JAXB将自动绑定Java类中的每个非静态的（static）、非瞬态的（由@XmlTransient标注）字段到XML。其他值还有XmlAccessType.PROPERTY和XmlAccessType.NONE。

@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。

三、代码实例

1、工具类

package com.guor.demo.beanToXml;

import java.io.StringReader;
import java.io.StringWriter;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

public class JaxbUtil {
    /**
     * JavaBean装换成xml 默认编码UTF-8
     *
     * @param obj
     * @return
     */
    public static String converTomXml(Object obj) {
        return converToXml(obj, "UTF-8");
    }

    /**
     * JavaBean装换成xml
     *
     * @param obj
     * @param encoding
     * @return
     */
    private static String converToXml(Object obj, String encoding) {
        String result = null;
        try {
            JAXBContext context = JAXBContext.newInstance(obj.getClass());
            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
            marshaller.setProperty(Marshaller.JAXB_ENCODING, encoding);
            StringWriter writer = new StringWriter();
            marshaller.marshal(obj, writer);
            result = writer.toString();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    /**
     * xml装换成JavaBean
     *
     * @param xml
     * @param c
     * @return
     */
    @SuppressWarnings("unchecked")
    public static <T> T converyToJavaBean(String xml, Class<T> c) {
        T t = null;
        try {
            JAXBContext context = JAXBContext.newInstance(c);
            Unmarshaller unmarshaller = context.createUnmarshaller();
            t = (T) unmarshaller.unmarshal(new StringReader(xml));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return t;
    }
}

2、简单类型

（1）单实体类转换

package com.guor.demo.beanToXml;

import java.util.Date;

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;
import javax.xml.bind.annotation.XmlType;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
@XmlType(name = "book", propOrder = { "author", "calendar", "price", "id" })
public class Book {
    @XmlElement(required = true)
    private String author;
    @XmlElement(name = "price_1", required = true)
    private float price;
    @XmlElement
    private Date calendar;
    @XmlAttribute
    private Integer id;

    /**
     *
     * @return
     */
    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public float getPrice() {
        return price;
    }

    public void setPrice(float price) {
        this.price = price;
    }

    public Date getCalendar() {
        return calendar;
    }

    public void setCalendar(Date calendar) {
        this.calendar = calendar;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @Override
    public String toString() {
        return "Book [author=" + author + ", price=" + price + ", calendar=" + calendar + ", id=" + id + "]";
    }
}

（2）test

package com.guor.demo.beanToXml;

import java.util.Date;
import org.junit.Test;
import javax.xml.bind.JAXBException;

@SuppressWarnings("unused")
public class JaxbTest1 {
    /**
     * @throws JAXBException
     */
    @Test
    public void showMarshaller() {
        Book book = new Book();
        book.setId(100);
        book.setAuthor("lin");
        book.setCalendar(new Date());
        book.setPrice(23.56f);
        String str = JaxbUtil.converTomXml(book);
        System.out.println(str);

    }

    /**
     * @throws JAXBException
     */
    @Test
    public void showUnMarshaller() {
        String str = "<?xml version =\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>" + "<book id =\"100\">"
                + "<author>lin</author>" + "<calendar>2018-9-3T11:58.006</calendar>" + "<price_1>23.56</price_1>"
                + "</book>";
        Book book = JaxbUtil.converyToJavaBean(str, Book.class);
        System.out.println(book);
    }
}

（3）控制台输出

JavaBean与xml互转的方法详解

3、类中包含复杂对象的转换

（1）实体类1

package com.guor.demo.beanToXml;

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;
import javax.xml.bind.annotation.XmlType;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "student")
@XmlType(propOrder = {})
public class Student {
    @XmlAttribute
    private Integer id;
    @XmlElement
    private String name;
    @XmlElement(name = "role")
    private Role role;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Role getRole() {
        return role;
    }

    public void setRole(Role role) {
        this.role = role;
    }

    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + ", role=" + role + "]";
    }
}

（2）实体类2

package com.guor.demo.beanToXml;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlType;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(propOrder = { "name", "desc" })
public class Role {
    @XmlElement
    private String name;
    @XmlElement
    private String desc;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }

    @Override
    public String toString() {
        return "Role [name=" + name + ",desc=" + desc + "]";
    }
}

（3）test

package com.guor.demo.beanToXml;

import org.junit.Test;

public class JaxbTest2 {
    @Test
    public void showMarshaller() {
        Student student = new Student();
        student.setId(12);
        student.setName("nihao");
        Role role = new Role();
        role.setDesc("管理");
        role.setName("班长");
        student.setRole(role);
        String str = JaxbUtil.converTomXml(student);
        System.out.println(str);

    }

    @Test
    public void showUnMarshaller() {
        String str = "<?xml version =\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>" + "<student id =\"12\">"
                + "<name>nihao</name>" + "<role>" + "<desc>管理</desc>" + "<name>班长</name>" + "</role>" + "</student>";
        Student student = JaxbUtil.converyToJavaBean(str, Student.class);
        System.out.println(student);
    }
}

（4）控制台输出

JavaBean与xml互转的方法详解

4、集合对象的转换（同样适用于Set）

（1）实体类1

package com.guor.demo.beanToXml;

import java.util.List;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElementWrapper;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "country")
@XmlType(propOrder = { "name", "provinceList" })
public class Country {
    @XmlElement(name = "country_name")
    private String name;

    @XmlElementWrapper(name = "provinces")
    @XmlElement(name = "province")
    private List<Province> provinceList;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<Province> getProvinceList() {
        return provinceList;
    }

    public void setProvinceList(List<Province> provinceList) {
        this.provinceList = provinceList;
    }

    @Override
    public String toString() {
        return "Country [name = " + name + ",provinceList" + provinceList + "]";
    }

}

（2）实体类2

package com.guor.demo.beanToXml;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlType;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(propOrder = { "name", "provCity" })
public class Province {
    @XmlElement(name = "province_name")
    private String name;
    @XmlElement(name = "prov_city")
    private String provCity;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getProvCity() {
        return provCity;
    }

    public void setProvCity(String provCity) {
        this.provCity = provCity;
    }

    @Override
    public String toString() {
        return "Province [name=" + name + ", provCity=" + provCity + "]";
    }
}

（3）test

package com.guor.demo.beanToXml;

import java.util.List;
import java.util.ArrayList;

import org.junit.Test;

public class JaxbTest3 {

    @Test
    public void showShaller() {
        Country country = new Country();
        country.setName("中国");
        List<Province> list = new ArrayList<Province>();
        Province province = new Province();
        province.setName("辽宁省");
        province.setProvCity("大连市");
        Province province2 = new Province();
        province2.setName("黑龙江省");
        province2.setProvCity("哈尔滨市");
        list.add(province);
        list.add(province2);
        country.setProvinceList(list);
        String str = JaxbUtil.converTomXml(country);
        System.out.println(str);
    }

    @Test
    public void showUnShaller() {
        String str = "<?xml version =\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>" + "<country>"
                + "<country_name>中国</country_name>" + "<provinces>" + "<province>"
                + "<province_name>辽宁省</province_name>" + "<prov_city>大连市</prov_city>" + "</province>" + "<province>"
                + "<province_name>黑龙江省</province_name>" + "<prov_city>哈尔滨市</prov_city>" + "</province>" + "</provinces>"
                + "</country>";
        Country country = JaxbUtil.converyToJavaBean(str, Country.class);
        System.out.println(country);
    }
}

（4）控制台输出

JavaBean与xml互转的方法详解

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版权声明：程序员胖胖胖虎阿发表于 2022年9月12日上午12:56。
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