Web编程学习五:使用Jersey和JPA来创建RESTfulWebService - 数据库编程

public Employee read(@PathParam("id") long id) { long start = System.currentTimeMillis(); System.out.println("EmployeeController.read() started"); EntityManager em = LocalEntityManagerFactory.createEntityManager(); try { return em.find(Employee.class, id); } finally { em.close(); System.out.println("Getting data took " + (System.currentTimeMillis() - start) + "ms."); } } @GET @Produces({ MediaType.TEXT_XML }) public List read() { long start = System.currentTimeMillis(); System.out.println("EmployeeController.read() started"); EntityManager em = LocalEntityManagerFactory.createEntityManager(); try { Query q = em.createQuery("SELECT e FROM Employee e"); List result = q.getResultList(); return result; } finally { em.close(); System.out.println("Getting data took " + (System.currentTimeMillis() - start) + "ms."); } } }
这里实现了两个GET接口，一个按照ID返回单个Employee对象，另一个返回全部Employee对象。

5.准备几条测试数据，插入到数据库表中。