JAXB XML到java object的转换

JAXB是Java Architecture for XML Binding的缩写。使用JAXB注解将Java对象转换成XML文件。在这篇教程中，我们将会展示如何使用JAXB来做以下事情：

1. marshall 将java对象转化成xml文件

2. unmarshalling 将xml内容转换成java对象

JAXB 注解(Annotation)

如果一个对象需要被转换成XML文件，或者从XML文件中生成，该对象需要用JAXB注解来标注。这些注解光凭名字就知道是什么意思了。具体可参考官网：jaxb guide

package com.jaxb.core;

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;
    }

}

对象转换成XML

JAXB marshalling例子，将customer对象转换成XML文件。jaxbMarshaller.marshal()包含了许多重载方法，哪个输出符合你的要求就选择哪个方法。

package com.jaxb.core;

import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;

public class JAXBExample {
    public static void main(String[] args) {

      Customer customer = new Customer();
      customer.setId(100);
      customer.setName("benson");
      customer.setAge(23);

      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：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer id="100">
    <age>23</age>
    <name>benson</name>
</customer>

XML转换成对象：

JAXB unmarshalling例子，将XML文件内容转换成customer对象。jaxbMarshaller.unmarshal()包含了许多重载方法，哪个适合你的输出，你就选择哪个方法。

package com.jaxb.core;

import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

public class JAXBExample {
    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();
      }

    }
}