JAXB : Stands for Java Architecture for XML binding. This framework helps us to convert Xml data to java content and Vice versa.
JaxB mainly uses two terminologies,
1. Unmarshalling : Reading Xml to Java content.
2. Marshalling : Writing Java Content to Xml
POC on UnMarshalling a sample XML file usercredentials.xml to Java Objects as below
Technologies used in this POC:
1. JDK 1.7
2. Maven 3.X
3. XSD
4. XML
5. JAXB
6. Eclipse IDE
Create a new maven Project in eclipse.
Open the pom.xml add the dependencies and plugin as below.
Create a folder called schema (not necessarily required) under src\main\resources of the project. and place the xsd file in the schema folder.
It generates XML bind classes from the XSD. We are using XSD in this Project because, so that strict structure of XML followed. even if there is a mismatch in the tag, XML will not be loaded.
Lets create a singleton class UnMarshallXmlToJava.java
Lets create one more class TestingUnMarshaling.java to test the code.
Output:
JaxB mainly uses two terminologies,
1. Unmarshalling : Reading Xml to Java content.
2. Marshalling : Writing Java Content to Xml
POC on UnMarshalling a sample XML file usercredentials.xml to Java Objects as below
<?xml version="1.0" encoding="UTF-8"?>
<config>
<Users>
<user>
<username>ABC</username>
<password>ABC@123</password>
</user>
<user>
<username>BBC</username>
<password>BBC@123</password>
</user>
<user>
<username>CBC</username>
<password>CBC@123</password>
</user>
</Users>
</config>
Technologies used in this POC:
1. JDK 1.7
2. Maven 3.X
3. XSD
4. XML
5. JAXB
6. Eclipse IDE
Create a new maven Project in eclipse.
Open the pom.xml add the dependencies and plugin as below.
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.learning</groupId>
<artifactId>jaxbunmarshalling</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>commons-configuration</groupId>
<artifactId>commons-configuration</artifactId>
<version>1.6</version>
</dependency>
<dependency>
<groupId>javax.xml.bind</groupId>
<artifactId>jaxb-api</artifactId>
<version>2.2.6</version>
</dependency>
</dependencies>
<build>
<plugins>
<!-- JAXB xjc plugin that invokes the xjc compiler to compile XML schema
into Java classes. -->
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>jaxb2-maven-plugin</artifactId>
<version>1.5</version>
<executions>
<execution>
<goals>
<goal>xjc</goal>
</goals>
</execution>
</executions>
<configuration>
<schemaDirectory>${basedir}/src/main/resources/schema</schemaDirectory>
<packageName>com.learning.usercredentials</packageName>
<outputDirectory>${basedir}/src/main/java</outputDirectory>
<removeOldOutput>false</removeOldOutput>
<clearOutputDir>false</clearOutputDir>
<forceRegenerate>true</forceRegenerate>
</configuration>
</plugin>
</plugins>
</build>
</project>
xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="config">
<xs:complexType>
<xs:sequence>
<xs:element name="Users">
<xs:complexType>
<xs:sequence>
<xs:element name="user" maxOccurs="unbounded" minOccurs="0">
<xs:complexType>
<xs:sequence>
<xs:element type="xs:string" name="username"/>
<xs:element type="xs:string" name="password"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
Create a folder called schema (not necessarily required) under src\main\resources of the project. and place the xsd file in the schema folder.
It generates XML bind classes from the XSD. We are using XSD in this Project because, so that strict structure of XML followed. even if there is a mismatch in the tag, XML will not be loaded.
Lets create a singleton class UnMarshallXmlToJava.java
package com.learning.user.unmarshal;
import java.io.File;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import com.learning.usercredentials.Config;
import com.learning.usercredentials.Config.Users.User;
public class UnMarshallXmlToJava {
/*
* Reason for SingletonClass is, Keep on generating java contents of XML
* data is a memory overhead, so use it only required. So we load the XML
* data and exposing to the outside world through a method.
*
*/
private static UnMarshallXmlToJava unMarshall = null;
private static Config config = null;
private UnMarshallXmlToJava() {
// Providing location of the xml file to file Object
try {
File xmlfile = new File(
"src/main/resources/usercredentials.xml");
JAXBContext context = JAXBContext.newInstance("com.learning.usercredentials");
// creating an Unsmarshaller instance.
Unmarshaller unmarshaller = context.createUnmarshaller();
// loading the file object to the unmarshaller, and return type is
// typecasted to Config Class, by this Xml data is converted to java
// objects
config = (Config) unmarshaller.unmarshal(xmlfile);
} catch (JAXBException e) {
e.printStackTrace();
}
}
public static UnMarshallXmlToJava getInstance() {
if (unMarshall == null) {
unMarshall = new UnMarshallXmlToJava();
return unMarshall;
}
return null;
}
// returning the coverted XML to java content as a map.
public Map<String, String> getUserCredentials() {
Map<String, String> map = new HashMap<String, String>();
List<User> userList = config.getUsers().getUser();
for (User user : userList) {
map.put(user.getUsername(), user.getPassword());
}
return map;
}
}
Lets create one more class TestingUnMarshaling.java to test the code.
package com.learning.user.unmarshal;
import java.util.Map;
import java.util.Map.Entry;
public class TestingUnMarshaling {
public static void main(String[] args) {
Map<String, String> usersMap = UnMarshallXmlToJava.getInstance().getUserCredentials();
for (Entry<String, String> userEntry : usersMap.entrySet()) {
System.out.println("*********************************");
System.out.println("UserName : " + userEntry.getKey());
System.out.println("Password : " + userEntry.getValue());
System.out.println("*********************************");
}
}
}
Output:
*********************************
UserName : ABC
Password : ABC@123
*********************************
*********************************
UserName : BBC
Password : BBC@123
*********************************
*********************************
UserName : CBC
Password : CBC@123
*********************************
EmoticonEmoticon