Jaxb2 实现JavaBean与xml互转

最新推荐文章于 2023-09-21 16:48:41 发布

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本文深入解析JAXB（Java Architecture for XML Binding）技术，介绍其原理、重要概念以及如何在Java中使用JAXB进行XML与Java对象之间的转换。通过提供示例代码，展示如何使用JAXB工具类将JavaBean转换为XML和从XML转换回JavaBean的过程。

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。

package utils;

import java.io.StringReader;
import java.io.StringWriter;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
/**
 * Jaxb2工具类
 * @author		zhuc
 */
public class JaxbUtil {

	public static String convertToXml(Object obj) {
		return convertToXml(obj, "UTF-8");
	}

	/**
	 * JavaBean转换成xml
	 * @param obj
	 * @param encoding 
	 * @return 
	 */
	public static String convertToXml(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转换成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;
	}
}

package t1;

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;

/**
 * @author		zhuc
 * @create		2013-3-29 下午2:49:48
 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
@XmlType(name = "book", propOrder = { "name","author", "calendar", "price", "id" })
public class Book {
	@XmlElement
	private String name;
	@XmlElement(required = true)
	private String author;
	@XmlElement(name = "price_1", required = true)
	private float price;
	@XmlElement
	private Date calendar;
	@XmlAttribute
	private Integer id;
	/**
	 * @return the author
	 */
	public String getAuthor() {
		return author;
	}

	/**
	 * @return the price
	 */
	public float getPrice() {
		return price;
	}

	/**
	 * @return the calendar
	 */
	public Date getCalendar() {
		return calendar;
	}

	/**
	 * @return the id
	 */
	public Integer getId() {
		return id;
	}

	/**
	 * @param author the author to set
	 */
	public void setAuthor(String author) {
		this.author = author;
	}

	/**
	 * @param price the price to set
	 */
	public void setPrice(float price) {
		this.price = price;
	}

	/**
	 * @param calendar the calendar to set
	 */
	public void setCalendar(Date calendar) {
		this.calendar = calendar;
	}

	/**
	 * @param id the id to set
	 */
	public void setId(Integer id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

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

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

package t2;

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

/**
 * @author		zhuc
 * @create		2013-3-29 下午2:51:52
 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(propOrder = { "name", "desc" })
public class Role {
	@XmlElement
	private String name;
	@XmlElement
	private String desc;
	/**
	 * @return the name
	 */
	public String getName() {
		return name;
	}

	/**
	 * @return the desc
	 */
	public String getDesc() {
		return desc;
	}

	/**
	 * @param name the name to set
	 */
	public void setName(String name) {
		this.name = name;
	}
	/**
	 * @param desc the desc to set
	 */
	public void setDesc(String desc) {
		this.desc = desc;
	}

	/* (non-Javadoc)
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString() {
		return "Role [name=" + name + ", desc=" + desc + "]";
	}

}

package t2;
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;

/**
 * @author		zhuc
 * @create		2013-3-29 下午2:51:44
 */
@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;
	/**
	 * @return the id
	 */
	public Integer getId() {
		return id;
	}

	/**
	 * @return the name
	 */
	public String getName() {
		return name;
	}

	/**
	 * @return the role
	 */
	public Role getRole() {
		return role;
	}

	/**
	 * @param id the id to set
	 */
	public void setId(Integer id) {
		this.id = id;
	}

	/**
	 * @param name the name to set
	 */
	public void setName(String name) {
		this.name = name;
	}

	/**
	 * @param role the role to set
	 */
	public void setRole(Role role) {
		this.role = role;
	}

	/* (non-Javadoc)
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", role=" + role + "]";
	}

}

package t2;
import org.junit.Test;

import utils.JaxbUtil;

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

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

package t3;
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 getProvCity() {
		return provCity;
	}

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

	public String getName() {
		return name;
	}

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

}

package t3;
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 List<Province> getProvinceList() {
		return provinceList;
	}

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

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

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

}

package t3;

import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
import utils.JaxbUtil;

public class JaxbTest3 {

	@Test
	public void showMarshaller() {
		Country country = new Country();
		country.setName("中国");
		List<Province> list = new ArrayList<Province>();
		Province province = new Province();
		province.setName("江苏省");
		province.setProvCity("南京市");
		Province province2 = new Province();
		province2.setName("浙江省");
		province2.setProvCity("杭州市");
		list.add(province);
		list.add(province2);
		country.setProvinceList(list);
		String str = JaxbUtil.convertToXml(country);
		System.out.println(str);
	}
	@Test
	public void showUnMarshaller() {
		String str = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>"+
			"<country>"+
			"    <country_name>中国</country_name>"+
			"    <provinces>"+
			"        <province>"+
			"            <province_name>江苏省</province_name>"+
			 "           <prov_city>南京市</prov_city>"+
			"        </province>"+
			 "       <province>"+
			 "           <province_name>浙江省</province_name>"+
			 "           <prov_city>杭州市</prov_city>"+
			 "       </province>"+
			"    </provinces>"+
			"</country>";
		Country country = JaxbUtil.converyToJavaBean(str, Country.class);
		System.out.println(country);
	}
	
}

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