java& XML Tutorial (11) JAXB implements XML and Java object transformations

JAXB is the abbreviation for the Java Architecture for XML binding, which is used to establish a mapping between Java classes and XML to help developers easily convert XML and Java objects to each other.
This article introduces the use of JAXB in a simple example. First we need to look at the APIs that JAXB uses frequently.

• Jaxbcontext class. Is the entrance to the application. Used to manage Xml/java binding information.
• Marshaller interface. Serializes a Java object into XML data.

• Unmarshaller interface that deserializes XML data into Java objects.

• @XmlType, mapping a Java class or enumeration type to an XML Schema type

• @XmlAccessorType (Xmlaccesstype.field). Controls the serialization of a field or property. field indicates that JAXB will voluntarily bind itself to each non-static (static), non-transient (@xmltransient callout) field in the Java class to XML.

  Other values are Xmlaccesstype.property and Xmlaccesstype.none.

• @XmlAccessorOrder, controlling the ordering of properties and fields in the JAXB binding class
• @XmlJavaTypeAdapter. Use a custom adapter (that is, extend the abstract class XMLAdapter and overwrite the marshal () and Unmarshal () methods) to serialize the Java class to XML.

• @XmlElementWrapper, for arrays or collections (that is, member variables that include multiple elements), generate an XML element (called a wrapper) that wraps the array or collection.
• @XmlRootElement, Map a Java class or enumeration type to an XML element.
• @XmlElement, a property of the Java class is mapped to an XML element with the same name as the property.

• @XmlAttribute. Maps a property of a Java class to an XML property with the same name as the property.

We need to bind Java bean content such as the following:
Employee.java

 PackageNet.csdn.beans;ImportJavax.xml.bind.annotation.XmlAccessType;ImportJavax.xml.bind.annotation.XmlAccessorType;ImportJavax.xml.bind.annotation.XmlRootElement;ImportJavax.xml.bind.annotation.XmlType;@XmlAccessorType(Xmlaccesstype.field)@XmlRootElement  @XmlType(name ="Employee", Proporder = {"Name","Age","Role","Gender"}) Public  class Employee {    PrivateString name;PrivateString gender;Private intAgePrivateString role; PublicStringGetName() {returnName } Public void SetName(String name) { This. name = name; } PublicStringGetgender() {returnGender } Public void Setgender(String gender) { This. gender = gender; } Public int Getage() {returnAge } Public void Setage(intAge) { This. Age = Age; } PublicStringGetrole() {returnRole } Public void Setrole(String role) { This. role = role; }@Override     PublicStringtoString() {return "Employee:: Name="+ This. Name +"Age="+ This. Age +"Gender="+ This. Gender +"role="+ This. role; }}

XML file contents that need to be converted to Java objects such as the following:
Employee.xml

<?
xml version="1.0"?><employee id="1"> <name>Pankaj</name> <age>29</age> <role>Java Developer</role> <gender>Male</gender></employee>

Next, write the sample code:
Testjaxb.java

Package Net. Csdn. Test;Import Java. IO. InputStream;Import Java(i). StringReader;Import Java. IO. StringWriter;Import Javax. XML. Bind. Jaxbcontext;Import Javax. XML. Bind. Marshaller;Import Javax. XML. Bind. Unmarshaller;Import Net. Csdn. Beans. Employee;import org. JUnit. Test;public class Testjaxb {@Test public void testxml2obj () throws Exception {InputStream is = Thread. CurrentThread(). Getcontextclassloader(). getResourceAsStream("Employee.xml");byte[] bytes = new Byte[is. Available()];Is. Read(bytes);String xmlstr = new String (bytes);Jaxbcontext context = Jaxbcontext. newinstance(Employee. Class); Unmarshaller Unmarshaller = Context. Createunmarshaller(); Employee EMP = (employee) Unmarshaller. Unmarshal(New StringReader (XMLSTR));System. out. println(EMP);} @Test public void Testobj2xml () {Employee EMP = new Employee ();Emp. Setage(Ten);Emp. Setgender("Male");Emp. SetName("Jane");Emp. Setrole("Teacher");String xmlstr = TESTJAXB. Converttoxml(EMP,"Utf-8"); System. out. println(XMLSTR);} 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; } }

Perform the Testobj2xml test method. Console output:

<?xml version="1.0" encoding="utf-8" standalone="yes"?><employee>    <name>Jane</name>    <age>10</age>    <role>Teacher</role>    <gender>Male</gender></employee>

Perform the Testxml2obj test method. Console output:

Employee:Name=Pankaj Age=29 Gender=Male Role=Java Developer

Note: In this example, using JUNIT4 as the Unit Test tool, click the Window->show view->outline menu in Eclipse to open the outline view, Right-click on the Testxml2obj and Testobj2xml methods to->run as->junit test.

java& XML Tutorial (11) JAXB implements XML and Java object transformations