Web編程學(xué)習(xí)五:使用Jersey和JPA來(lái)創(chuàng)建RESTfulWebService

package sample;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
@Entity
@Table(name = "employee")
public class Employee {
	@Id
	@Column(name = "userId")
	private Long id;
	@Column(name = "firstName")
	private String firstName;
	@Column(name = "lastName")
	private String lastName;

	public long getId() {
	return id;
	}

	public void setId(long id) {
	this.id = id;
	}

	public String getFirstName() {
	return firstName;
	}

	public void setFirstName(String firstName) {
	this.firstName = firstName;
	}

	public String getLastName() {
	return lastName;
	}

	public void setLastName(String lastName) {
	this.lastName = lastName;
	}
}

	
	org.eclipse.persistence.jpa.PersistenceProvider
	sample.Employee
	
	
	
	
	
	
	
 

 
 
 RestProjectTest 
  
 Jersey REST Service 
 com.sun.jersey.spi.container.servlet.ServletContainer 
  
 com.sun.jersey.config.property.packages 
 sample 
  
  
 com.sun.jersey.api.json.POJOMappingFeature 
 true 
  
 1 
  
  
 Jersey REST Service 
 /* 
  
 
 sample.LocalEntityManagerFactory 
  
 

注意添加了一個(gè)監(jiān)聽(tīng)器LocalEntityManagerFactory，實(shí)現(xiàn)了ServletContextListener類(lèi)，它可以在應(yīng)用啟動(dòng)和關(guān)閉的時(shí)候后自動(dòng)調(diào)用。

package sample;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@WebListener
public class LocalEntityManagerFactory implements ServletContextListener {
	private static EntityManagerFactory emf;

	@Override
	public void contextInitialized(ServletContextEvent event) {
	emf = Persistence.createEntityManagerFactory("EmployeePU");
	
	System.out.println("ServletContextListener started");
	}

	@Override
	public void contextDestroyed(ServletContextEvent event) {
	emf.close();
	System.out.println("ServletContextListener destroyed");
	}

	public static EntityManager createEntityManager() {
	if (emf == null) {
	throw new IllegalStateException("Context is not initialized yet.");
	}
	return emf.createEntityManager();
	}
}

package sample;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.Query;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

@Path("/employee")
public class EmployeeController {
	@GET
	@Produces({ MediaType.TEXT_XML })
	@Path("{id}")
	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.");
	}
	}

}