Detailed explanation of sample code for Jaxb2 to implement Bean and XML mutual conversion

1. Important class description

JAXBContext class is the entry point of the application and is used to manage XML/Java binding information.

MarshallerInterface, converts Java pairs into XML data.

Unmarshaller interface, converts XML into Javaobject.

@XmlType, maps Java classes or enumeration types to XML schema types

@XmlAccessorType(XmlAccessType.FIELD), controls the serialization of fields or attributes. FIELD means that JAXB will automatically bind every non-static(static) and

non-transient (marked by @XmlTransient) field in the Java class to XML. Other values ​​are XmlAccessType.PROPERTY and XmlAccessType.NONE.

@XmlAccessorOrder, controls the ordering of properties and fields in JAXB binding classes.

@XmlJavaTypeAdapter, uses a custom adapter (i.e. extends abstract class XmlAdapter and overrides the marshal() and unmarshal() methods) to serialize Java classes to XML.

@XmlElementWrapper, for an array or collection (that is, a member variable that contains multiple elements), generates an XML element that wraps the array or collection (called a wrapper device).

@XmlRootElement, maps Java classes or enumeration types to XML elements.

@XmlElement, maps an attribute of a Java class to an XML element with the same name as the attribute.

@XmlAttribute maps an attribute of a Java class to an XML attribute with the same name as the attribute.

2. Example

1. JavaBean

import java.util.Date;
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;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

import com.tzz.util.xml.JaxbDateSerializer;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement(name = "country")
@XmlType(propOrder = { "id", "createDate", "name", "provinceList" })
public class Country {

	private Integer id;
	@XmlJavaTypeAdapter(JaxbDateSerializer.class)
	private Date createDate;
	@XmlElement(name = "name")
	private String name;
	@XmlElementWrapper(name = "provinces")
	@XmlElement(name = "province")
	private List<Province> provinceList;

	public Integer getId() {
		return id;
	}

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

	public Date getCreateDate() {
		return createDate;
	}

	public void setCreateDate(Date createDate) {
		this.createDate = createDate;
	}

	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;
	}
}

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 = "name")
	private String name;
	@XmlElement(name = "provCity")
	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;
	}
}

2. Conversion tool class

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;

/**
 * Jaxb 2.0
 *
 */
public class JaxbXmlUtil {

	@SuppressWarnings("unchecked")
	public static <T> T xmlToBean(String xml, Class<T> beanClass) {
		try {
			JAXBContext jaxbContext = JAXBContext.newInstance(beanClass);
			Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
			T user = (T) unmarshaller.unmarshal(new StringReader(xml));
			return user;
		} catch (JAXBException e) {
			e.printStackTrace();
			return null;
		}
	}

	/**Bean转XML*/
	public static String beanToXml(Object obj) {
		String result = null;
		try {
			JAXBContext context = JAXBContext.newInstance(obj.getClass());
			Marshaller marshaller = context.createMarshaller();
			//决定是否在转换成xml时同时进行格式化（即按标签自动换行，否则即是一行的xml）
			marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
			//Marshaller.JAXB_ENCODING xml的编码方式
			marshaller.setProperty(Marshaller.JAXB_ENCODING, "utf-8");
			StringWriter writer = new StringWriter();
			marshaller.marshal(obj, writer);
			result = writer.toString();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return result;
	}
}

3. Test class

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import org.junit.Test;

import com.tzz.test.util.xml.entity.Country;
import com.tzz.test.util.xml.entity.Province;
import com.tzz.util.xml.JaxbXmlUtil;

public class TestJaxbBeanToXmlUtil {

	@Test
	public void testBeanToXml() {
		Country country = new Country();
		country.setId(1);
		country.setCreateDate(new Date());
		country.setName("中国");
		
		List<Province> list = new ArrayList<Province>();
		Province province = new Province();
		province.setName("广东省");
		province.setProvCity("广州市");
		Province province2 = new Province();
		province2.setName("湖南省");
		province2.setProvCity("长沙市");
		list.add(province);
		list.add(province2);
		country.setProvinceList(list);

		String xml = JaxbXmlUtil.beanToXml(country);
		System.out.println(xml);
	}

	@Test
	public void testXmlToBean() {
		String xml = "<?xml version=&#39;1.0&#39; encoding=&#39;utf-8&#39; ?>" 
				+ "<country>" 
				+ "<id>1</id>"
				+ "<createDate>2016-03-10 09:36:01</createDate>" 
				+ "<name>中国</name>" 
				+ "<provinces>" 
				+ "<province><name>广东省</name><provCity>广州市</provCity></province>" 
				+ "<province><name>湖南省</name><provCity>长沙市</provCity></province>" 
				+ "</provinces>" 
				+ "</country>";
		Country country = JaxbXmlUtil.xmlToBean(xml, Country.class);
		System.out.println(country.getId() + "--" + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")
				.format(country.getCreateDate()) + "--" + country.getName());
		for (Province p : country.getProvinceList()) {
			System.out.println(p.getName() + "---" + p.getProvCity());
		}
	}
}

4. Test results

4.1. Run testBeanToXml method

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<country>
    <id>1</id>
    <createDate>2016-03-10 05:24:57</createDate>
    <name>中国</name>
    <provinces>
        <province>
            <name>广东省</name>
            <provCity>广州市</provCity>
        </province>
        <province>
            <name>湖南省</name>
            <provCity>长沙市</provCity>
        </province>
    </provinces>
</country>

4.2. Run testXmlToBean method

1--2016-03-10 09:36:01--中国
广东省---广州市
湖南省---长沙市

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