使用 Apache Wink 和 OpenJPA 构建 REST 资源（4）
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- UID
- 1066743
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使用 Apache Wink 和 OpenJPA 构建 REST 资源（4）
action 类样例 action 类定义一个资源可以实现的所有 HTTP CRUD 操作的实现。Apache Wink 收到 HTTP 请求，然后将一个包装的 HTTP 请求分配到适当的方法（写入 action 类中的）。每个 HTTP 请求应该映射到 action 类的一个方法中，具体根据 HTTP 请求参数、资源方法定义以及 MIME 类型而定。
清单 4 显示如何为 Employee 资源创建一个 action 类。在本示例中，可以创建一个 EmployeeAction 类来实现 Apache Wink RESTful 服务。它由 4 个方法组成，每个代表一个 CRUD 操作。
清单 4. Employee action 类实现1
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| package rest.action;
import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import openJpa.mediator.EmployeeOpenJpaMediator;
import openJpa.model._Employee;
import rest.resource.Employee;
@Path(value = "/employee")
public class EmployeeAction {
/**
* @param employee
* CREATE: @return This method is used to create new Employee
*/
@POST
@Consumes(value = { MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON })
@Produces(value = { MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON })
public Response persistEmployee(Employee employee) {
EmployeeOpenJpaMediator dao = new EmployeeOpenJpaMediator();
_Employee _employee = employee.getEmployee();
try {
dao.beginTransaction();
dao.persist(_employee);
dao.commitTransaction();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
dao.rollbackTransaction();
return Response.status(400).entity(
"Employee create failed!").build();
} finally {
dao.close();
}
Employee employeeCreated = new Employee(_employee);
return Response.ok(employeeCreated).build();
}
/**
* @param id
* RETRIEVE: @return This method is used to retrieve a particular Employee
through employeeId
*/
@GET
@Path("/{id}")
@Produces(value = { MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML })
public Response findEmployee(@PathParam(value = "id") int id) {
EmployeeOpenJpaMediator employeeDao = new EmployeeOpenJpaMediator();
_Employee u = new _Employee();
try {
if ((u = (_Employee) employeeDao.getById(_Employee.class, id)) != null) {
return Response.ok(new Employee(u)).build();
} else {
return Response.status(404).entity(
"Employee id does not exist").build();
}
}catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
return Response.status(404).entity(
"Employee id does not exist").build();
}
}
/**
* @param employee
* UPDATE: @return this method is used to update a particular Employee
already existing
*/
@PUT
@Produces(value = { MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON })
@Consumes(value = { MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON })
public Response updateEmployee(Employee employee) {
EmployeeOpenJpaMediator ud = new EmployeeOpenJpaMediator();
_Employee _employee = employee.getEmployee();
try {
ud.beginTransaction();
ud.update(_employee);
ud.commitTransaction();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
ud.rollbackTransaction();
return Response.status(409).entity(
"Employee update failed!").build();
} finally {
ud.close();
}
Employee employeeUpdated = new Employee(_employee);
return Response.ok(employeeUpdated).build();
}
/**
* @param id
* DELETE: This method is used to delete a particular Employee through employeeId
*/
@DELETE
@Path("/{id}")
public Response deleteEmployee(@PathParam(value = "id") int id) {
EmployeeOpenJpaMediator pd = new EmployeeOpenJpaMediator();
_Employee _employee = (_Employee) pd.getById(_Employee.class, id);
if(_employee!=null){
try {
pd.beginTransaction();
pd.delete(_employee);
pd.commitTransaction();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
pd.rollbackTransaction();
return Response.status(400).entity(
"Employee delete had an error!").build();
} finally {
pd.close();
}
return Response.ok().build();
}
else{
return Response.status(400).entity(
"Employee ID does not exist!").build();
}
}
}
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