JAXB简单样例

参考网页：http://www.mkyong.com/java/jaxb-hello-world-example/
JAXB完整教程：https://jaxb.java.net/tutorial/
1.JAXB 依赖
maven项目使用JAXB首先需要添加jaxb api和jaxb impl,jaxb core(因为jaxb api 2.2.11 版本之后不再支持annomationReader，详见:http://*.com/questions/27046836/why-has-annotationreader-been-removed-from-jaxb-reference-implementation)：
jaxb api的maven dependency可以在这里找到：http://mvnrepository.com/artifact/javax.xml/jaxb-api
jaxb impl的maven dependency可以在这里找到：http://mvnrepository.com/artifact/com.sun.xml.bind/jaxb-impl
jaxb core的maven dependency可以在这里找到：http://mvnrepository.com/artifact/com.sun.xml.bind/jaxb-core
这里使用最新的版本，添加如下代码到pom.xml的dependencies当中：

<!-- http://mvnrepository.com/artifact/com.sun.xml.bind/jaxb-core -->
<dependency>
    <groupId>com.sun.xml.bind</groupId>
    <artifactId>jaxb-core</artifactId>
    <version>2.2.11</version>
</dependency>
<!-- http://mvnrepository.com/artifact/javax.xml/jaxb-api -->
<dependency>
    <groupId>javax.xml</groupId>
    <artifactId>jaxb-api</artifactId>
    <version>2.1</version>
</dependency>
<!-- http://mvnrepository.com/artifact/com.sun.xml.bind/jaxb-impl -->
<dependency>
    <groupId>com.sun.xml.bind</groupId>
    <artifactId>jaxb-impl</artifactId>
    <version>2.2.11</version>
</dependency>

2.JAXB注释
需要进行xml转换的类必须用JAXB注释（JAXB annotation）进行注释。

package com.mypackage;

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

@XmlRootElement
public class Customer {
    String name;
    int age;
    int id;
    public String getName() {
        return name;
    }
    @XmlElement
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    @XmlElement
    public void setAge(int age) {
        this.age = age;
    }
    public int getId() {
        return id;
    }
    @XmlAttribute
    public void setId(int id) {
        this.id = id;
    }
    @Override
    public String toString() {
        return "Customer [name=" + name + ", age=" + age + ", id=" + id + "]";
    }
}

3.将对象转换成XML
JAXB编组（marshall）对象成XML。

package com.mypackage;

import java.io.File;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class JAXBMarshallExample {
    public static void main(String[] args) {
        Customer customer = new Customer();
        customer.setId(1000);
        customer.setName("moon");
        customer.setAge(18);

        try {
            File file = new File("C:\\file.xml");
            JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);
            Marshaller jaxbMarshaller = jaxbContext.createMarshaller();

            // output pretty printed
            jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

            jaxbMarshaller.marshal(customer, file);
            jaxbMarshaller.marshal(customer, System.out);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

输出结果：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer id="1000">
    <age>18</age>
    <name>moon</name>
</customer>

4.将XML转换成对象
JAXB解组(unmarshall)XML成对象。

package com.mypackage;

import java.io.File;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

public class JAXBUnmarshallExample {
    public static void main(String[] args) {
        try {
            File file = new File("C:\\file.xml");
            JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class);

            Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
            Customer customer = (Customer) jaxbUnmarshaller.unmarshal(file);
            System.out.println(customer);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

程序输出：

Customer [name=moon, age=18, id=1000]