通過Accessor來取得相關的實體

1. 概述
   1. 通過主實體取得多個從實體
   2. 通過從實體取得對應的主實體
   3. 在Departments和Employees實體關聯中通過員工取得對應的部門和通過部門取得部門下的所有員工
2. 實現
   1. 通過員工取得部門名稱的代碼如下：public String findEmpDepartment(long employeeId) {<br /> EmployeesImpl employee = retrieveEmployeeById(employeeId);<br /> if (employee != null) {<br /> DepartmentsImpl department = employee.getDepartments();<br /> if (department != null) {<br /> return department.getDepartmentName();<br /> } else {<br /> return "Unassigned";<br /> } else {<br /> return null;<br /> }<br /> }<br />}
   2. 通過部門取得部門下的員工數代碼如下：/* Access an associated Employees entity from the Department entity */<br />public int findDeptEmployees(long departmentId) {<br /> DepartmentsImpl department = retrieveDepartmentById(departmentId);<br /> if (department != null) {<br /> RowIterator employees = department.getEmployees();<br /> return (employees.getRowCount());<br /> Row row ;<br /> while((row = employees.next())!= null){<br /> EmployeesImpl emp = (EmployeesImpl)row;<br /> System.out.println(emp.getFirstName() + " " + emp.getLastName());<br /> }<br /> } else {<br /> return 0;<br /> }<br />}

本文轉自Oracle Seeker：http://oracleseeker.com/2008/11/06/access_associated_entity_by_accessor_attribute/