JAXB的使用（java物件和xml文字的相互轉換）
阿新 • • 發佈：2019-02-02
JAXB（Java Architecture for XML Binding) 是一個業界的標準，是一項可以根據XML Schema產生Java類的技術。該過程中，JAXB也提供了將XML例項文件反向生成Java物件樹的方法，並能將Java物件樹的內容重新寫到XML例項文件。從另一方面來講，JAXB提供了快速而簡便的方法將XML模式繫結到Java表示，從而使得Java開發者在Java應用程式中能方便地結合XML資料和處理函式， 在JDK1.6時，JAXB 2.0是JDK 1.6的組成部分。JAXB 2.2.3是JDK 1.7的組成部分。
JDK中JAXB相關的重要Class和Interface：
JAXBContext類，是應用的入口，用於管理XML/Java繫結資訊。
Marshaller介面，將Java物件序列化為XML資料。
Unmarshaller介面，將XML資料反序列化為Java物件。
JDK中JAXB相關的重要Annotation：
- @XmlType，將Java類或列舉型別對映到XML模式型別
- @XmlAccessorType(XmlAccessType.FIELD) ，控制欄位或屬性的序列化。FIELD表示JAXB將自動繫結Java類中的每個非靜態的（static）、非瞬態的（由@XmlTransient標註）欄位到XML。其他值還有XmlAccessType.PROPERTY和XmlAccessType.NONE。
- @XmlAccessorOrder，控制JAXB 繫結類中屬性和欄位的排序。
- @XmlJavaTypeAdapter，使用定製的介面卡（即擴充套件抽象類XmlAdapter並覆蓋marshal()和unmarshal()方法），以序列化Java類為XML。
- @XmlElementWrapper ，對於陣列或集合（即包含多個元素的成員變數），生成一個包裝該陣列或集合的XML元素（稱為包裝器）。
- @XmlRootElement，將Java類或列舉型別對映到XML元素。
- @XmlElement，將Java類的一個屬性對映到與屬性同名的一個XML元素。
- @XmlAttribute，將Java類的一個屬性對映到與屬性同名的一個XML屬性。
例項
- 建立一個User類和一個Book類，其中User類含有一個Book類的集合屬性
User類：
package com.yaolong.jax2xml.bean;
import java.io.Serializable;
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 = "USER")
@XmlType(propOrder={"username","age","height","hobby","books"})
public class User implements Serializable{
private static final long serialVersionUID = 1L;
@XmlElement(name = "USERNAME")
private String username;
@XmlElement(name = "AGE")
private String age;
@XmlElement(name = "HEIGHT")
private String height;
@XmlElement(name = "HOBBY")
private String hobby;
@XmlElementWrapper(name = "BOOKS")
@XmlElement(name = "BOOK")
private List<Book> books;
public User() {
}
public User(String username, String age, String height, String hobby,List<Book> books) {
super();
this.username = username;
this.age = age;
this.height = height;
this.hobby = hobby;
this.books = books;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getHeight() {
return height;
}
public void setHeight(String height) {
this.height = height;
}
public String getHobby() {
return hobby;
}
public void setHobby(String hobby) {
this.hobby = hobby;
}
public List<Book> getBooks() {
return books;
}
public void setBook(List<Book> books) {
this.books = books;
}
@Override
public String toString() {
return "User [username=" + username + ", age=" + age + ", height="
+ height + ", hobby=" + hobby + ", books=" + books + "]";
}
}
Book類：
package com.yaolong.jax2xml.bean;
import java.io.Serializable;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
@XmlRootElement(name="BOOK")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(propOrder={"bookName","price","desc"})
public class Book implements Serializable{
private static final long serialVersionUID = 1L;
@XmlElement(name="DESCRIPTION")
private String desc;
@XmlElement(name="BOOKNAME")
private String bookName;
@XmlElement(name="PRICE")
private String price;
public Book(){
}
public Book(String desc, String bookName, String price) {
super();
this.desc = desc;
this.bookName = bookName;
this.price = price;
}
public String getBookName() {
return bookName;
}
public void setBookName(String bookName) {
this.bookName = bookName;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
public String getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc = desc;
}
@Override
public String toString() {
return "Book [desc=" + desc + ", bookName=" + bookName + ", price="
+ price + "]";
}
}
JaxB工具類：
package com.yaolong.jax2xml;
import java.io.StringReader;
import java.io.StringWriter;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
/**
* @Description:xml和物件相互轉換工具類
* @author:yaolong
* @data:2017年2月9日 下午10:46:57
* @version:1.0
*/
public class JaxbUtil {
/**
* JavaBean轉換成xml 預設編碼UTF-8
*
* @param obj
* @param writer
* @return
*/
public static String convertToXml(Object obj) {
return convertToXml(obj, "UTF-8");
}
/**
* JavaBean轉換成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);
marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);// 是否省略xml頭資訊
StringWriter writer = new StringWriter();
marshaller.marshal(obj, writer);
result = writer.toString();
} catch (Exception e) {
e.printStackTrace();
}
return result;
}
/**
* xml轉換成JavaBean
* @param xml
* @param c
* @return
* @throws JAXBException
*/
@SuppressWarnings("unchecked")
public static <T> T converyToJavaBean(String xml, Class<T> c)
throws JAXBException {
T t = null;
JAXBContext context = JAXBContext.newInstance(c);
Unmarshaller unmarshaller = context.createUnmarshaller();
t = (T) unmarshaller.unmarshal(new StringReader(xml));
return t;
}
}
測試類：
package com.yaolong.jax2xml;
import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.JAXBException;
import com.yaolong.jax2xml.bean.Book;
import com.yaolong.jax2xml.bean.User;
public class JaxbeanTest {
public static void main(String[] args) throws JAXBException {
//準備資料
Book book1 = new Book("葵花寶典","100元","欲練此功，必須自宮");
Book book2 = new Book("辟邪劍譜","120元","不用自宮也能練");
Book book3 = new Book("九陰真經","130元","練完此功，天下無敵");
List<Book> books = new ArrayList<Book>();
books.add(book1);
books.add(book2);
books.add(book3);
User user = new User("吳渣渣","23","170","睡覺",books);
//將物件轉化成xml文字
String xmlStr = JaxbUtil.convertToXml(user, "UTF-8");
System.out.println(xmlStr);
System.out.println("===================================================================================================");
//xml文字轉換成物件
String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>"
+ "<USER>"
+ "<USERNAME>吳渣渣</USERNAME>"
+ "<AGE>23</AGE>"
+ "<HEIGHT>170</HEIGHT>"
+ "<HOBBY>睡覺</HOBBY>"
+ "<BOOKS>"
+ "<BOOK>"
+ "<BOOKNAME>100元</BOOKNAME>"
+ "<PRICE>欲練此功，必須自宮</PRICE>"
+ "<DESCRIPTION>葵花寶典</DESCRIPTION>"
+ "</BOOK>"
+ "<BOOK>"
+ "<BOOKNAME>120元</BOOKNAME>"
+ "<PRICE>不用自宮也能練</PRICE>"
+ "<DESCRIPTION>辟邪劍譜</DESCRIPTION>"
+ "</BOOK>"
+ "<BOOK>"
+ "<BOOKNAME>130元</BOOKNAME>"
+ "<PRICE>練完此功，天下無敵</PRICE>"
+ "<DESCRIPTION>九陰真經</DESCRIPTION>"
+ "</BOOK>"
+ "</BOOKS>"
+ "</USER>";
User userBean = JaxbUtil.converyToJavaBean(xml, User.class);
System.err.println(userBean);
}
}
列印結果：
