Xpath = JxPath

Quite often while implementing   SOAP based service we  need to  traverse   xpath.

So, my XSD looks like this;

<?xml version="1.0" encoding="UTF-8"?>

<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:tns="myorg.xml.com" targetNamespace="myorg.xml.com">

<element name="employeeDetails">

<complexType >

<sequence>

<element name="employee" type="tns:Employee" minOccurs="1" maxOccurs="unbounded"/>

</sequence>

</complexType>

</element>

    <complexType name="Employee">

    <sequence>

    <element  name="employeeId" type="int" />

    <element name="employeeName" type="string" />

    <element name="department" type="tns:Department"/>

    <element name="EmployeeDesignation" type="tns:Designation"/>

    </sequence>

    </complexType>

    <complexType name="Department">

    <sequence>

    <element  name="departmentId" type="int" />

    <element name="departmentName" type="string" />

    </sequence>

    </complexType>

   

   <simpleType name="Designation">

    <restriction base="string">

    <enumeration value="Associate"/>

    <enumeration value="Software Engineer"/>

    <enumeration value="Senior Software Engineer"/>

    <enumeration value="Manager"/>

    <enumeration value="Executive"/>

   

    </restriction>

    </simpleType>

</schema>

And a sample XML:

<?xml version="1.0" encoding="UTF-8"?>

<tns:employeeDetails xmlns:tns="myorg.xml.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="myorg.xml.com Employee.xsd ">

  <employee>

    <employeeId>230</employeeId>

    <employeeName>Jim</employeeName>

    <department>

      <departmentId>1</departmentId>

      <departmentName>IT</departmentName>

    </department>

    <EmployeeDesignation>Associate</EmployeeDesignation>

  </employee>

 

  <employee>

    <employeeId>231</employeeId>

    <employeeName>Tim</employeeName>

    <department>

      <departmentId>12</departmentId>

      <departmentName>Admin</departmentName>

    </department>

    <EmployeeDesignation>Manager</EmployeeDesignation>

  </employee>

</tns:employeeDetails>

JXPath (http://commons.apache.org/jxpath/)  provides APIs for traversal of graphs of JavaBeans, DOM and other types of objects using the XPath syntax. Both child and attribute axis of a node is mapped to Java Beans Properties.

Below is the code to be used for xpath.

private Object traverseXpath(EmployeeDetails details , String xpath){

  JXPathContext context = JXPathContext.newContext(details);

  return context.getValue(xpath);

}

JXPath   supports indexed properties according to the JavaBeans specification. Hence  following xpath

Employee employee = (Employee)consumeDetails.traverseXpath(employeeDetails, "employee[1]");

System.out.println(employee.getEmployeeName());

will return the EmployeeName of  first object in the  list of employee.   Output will be “Jim”

Few points to be taken care:

1.       In XPath the first element of a collection has index 1, not 0.

2.       The node names in xpath should be as per the generated JAXB classes not the xml.

Example:

In the above XSD  inside Employee complex type we have following element

<element name="EmployeeDesignation" type="tns:Designation"/>

When classes are generated using XJC command we will have following property inside Employee Class

@XmlElement(name = "EmployeeDesignation", required = true)

protected Designation employeeDesignation;

but in XML we will have following node

<EmployeeDesignation>Associate</EmployeeDesignation>

 Following code

Object obj = consumeDetails.traverseXpath(employeeDetails, "employee[1]/EmployeeDesignation");

                  System.out.println(obj);

Will shoot JXPathNotFoundException.

But below code will

Object obj = consumeDetails.traverseXpath(employeeDetails, "employee[1]/EmployeeDesignation");

System.out.println(obj);

Generate output as “Associate” ,as expected