Agile Business Coach

Separate Domain and Persistence Layer

Ade completed the example of a separate domain and persistence layer. It uses xstream for persistence.

Example below:

Repository example:

import junit.framework.TestCase;

import java.util.List;

public class DepartmentTest extends TestCase {
public void testAddedEmployeesCanBeListed() {
Department sales = new Department("Sales");
Employee johnSmith = new Employee("John Smith");
sales.add(johnSmith);
Employee janeSmith = new Employee("Jane Smith");
sales.add(janeSmith);

List employees = sales.getAllEmployees();
assertEquals(2, employees.size());
assertTrue(employees.contains(johnSmith));
assertTrue(employees.contains(janeSmith));
}

public void testEmployeeCanBeTransferredFromOneDepartmentToAnother() {
Department sales = new Department("Sales");
Employee johnSmith = new Employee("John Smith");
sales.add(johnSmith);

Department marketing = new Department("Marketing");
sales.transfer(marketing, johnSmith);

List marketingEmployees = marketing.getAllEmployees();
assertEquals(1, marketingEmployees.size());
assertTrue(marketingEmployees.contains(johnSmith));

//confirm john's left the sales dept
List salesEmployees = sales.getAllEmployees();
assertEquals(0, salesEmployees.size());
assertFalse(salesEmployees.contains(johnSmith));
}

public void testPersistedDepartmentCanBeRetrieved() {
String name = "Sales";
Department sales = new Department(name);
Employee johnSmith = new Employee("John Smith");
sales.add(johnSmith);
Employee janeSmith = new Employee("Jane Smith");
sales.add(janeSmith);

DepartmentRepository repository = new DepartmentRepository();
repository.add(sales);

Department retrievedSalesDept = repository.findByName(name);
assertEquals(sales, retrievedSalesDept);

List employees = retrievedSalesDept.getAllEmployees();
assertEquals(2, employees.size());
assertTrue(employees.contains(johnSmith));
assertTrue(employees.contains(janeSmith));
}
}

================

import com.thoughtworks.xstream.XStream;

import java.io.FileWriter;
import java.io.IOException;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.File;
import java.util.List;
import java.util.Iterator;
import java.util.ArrayList;

public class DepartmentRepository {
private static final String FILE_NAME = "departmentRepository.xml";
private XStream xstream;

public DepartmentRepository() {
this.xstream = new XStream();
}

public void add(Department dept) {
try {
List departments = getExistingDepartments();
departments.add(dept);
xstream.toXML(departments, new FileWriter("departmentRepository.xml"));
} catch (IOException e) {
e.printStackTrace();
}
}

private List getExistingDepartments() throws FileNotFoundException {
File file = new File(FILE_NAME);
if (file.exists()) {
return (List) xstream.fromXML(new FileReader(FILE_NAME));
}
return new ArrayList();
}

public Department findByName(String name) {
XStream xstream = new XStream();
try {
List departments = getExistingDepartments();
for (Iterator iterator = departments.iterator(); iterator.hasNext();) {
Department department = (Department) iterator.next();
if (department.getName().equals(name)) {
return department;
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}

return null;
}
}
===================================

public class Employee {
private String name;

public Employee(String name) {
this.name = name;
}

public boolean equals(Object object) {
Employee other = (Employee) object;
return this.name.equals(other.name);
}
}
========================================

import java.util.ArrayList;
import java.util.List;

public class Department {
private String name;
private List employees;

public Department(String name) {
this.name = name;
this.employees = new ArrayList();
}

public void add(Employee employee) {
employees.add(employee);
}

public List getAllEmployees() {
return employees;
}

public void transfer(Department other, Employee employee) {
this.employees.remove(employee);
other.employees.add(employee);
}

public String getName() {
return name;
}

public boolean equals(Object object) {
Department other = (Department) object;
return this.name.equals(other.getName());
}
}

Posted by chrismatts at December 10, 2004 3:55 PM