JAVA JPA - 示例用法

JPA(Java Persistence API)是JSR(Java Specification Requests)的一部分，定义了一系列对象持久化的标准，目前实现这一规范的产品有Hibernate、TopLink等。

下面的示例程序是在jboss quickStart的基础上修改而来的

1、实体Bean：Member类

 package org.jboss.as.quickstart.hibernate4.model;

 import java.io.Serializable;

 import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
 import javax.persistence.SequenceGenerator;
 import javax.persistence.Table;
 import javax.validation.constraints.Digits;
 import javax.validation.constraints.NotNull;
 import javax.validation.constraints.Pattern;
 import javax.validation.constraints.Size;
 import javax.xml.bind.annotation.XmlRootElement;
 import org.hibernate.validator.constraints.Email;
 import org.hibernate.validator.constraints.NotEmpty;

 @Entity
 @XmlRootElement
 @Table(name = "MemberHibernate4Demo")
 public class Member implements Serializable {

     private static final long serialVersionUID = 3862416351900991824L;

     @Id
     @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "MEMBER_ID_GENERATOR")
     @SequenceGenerator(name = "MEMBER_ID_GENERATOR", sequenceName = "SEQ_MEMBER", allocationSize = 1)
     private Long id;

     @NotNull
     @Size(min = 1, max = 25)
     @Pattern(regexp = "[A-Za-z ]*", message = "must contain only letters and spaces")
     private String name;

     @NotNull
     @NotEmpty
     @Email
     private String email;

     @NotNull
     @Size(min = 9, max = 12)
     @Digits(fraction = 0, integer = 12)
     @Column(name = "phone_number")
     private String phoneNumber;

     private String address;

     public Long getId() {
         return id;
     }

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

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public String getEmail() {
         return email;
     }

     public void setEmail(String email) {
         this.email = email;
     }

     public String getPhoneNumber() {
         return phoneNumber;
     }

     public void setPhoneNumber(String phoneNumber) {
         this.phoneNumber = phoneNumber;
     }

     public String getAddress() {
         return address;
     }

     public void setAddress(String address) {
         this.address = address;
     }

     public String toString() {

         return "id:" + id + ",name:" + name + ",email:" + email
                 + ",phoneNumber:" + phoneNumber + ",address:" + address;
     }
 }

Member

注意：私有成员id上的注解@SequenceGenerator、@GeneratedValue演示Oracle中序列（Sequence）的用法。

2、服务接口 MemberService

 package org.jboss.as.quickstart.hibernate4.service;

 import java.util.List;

 import org.jboss.as.quickstart.hibernate4.model.Member;

 public interface MemberService {

     void addMember(Member member) throws Exception;

     void updateMember(Member member) throws Exception;

     void deleteMember(long id) throws Exception;

     Member findMember(long id) throws Exception;

     List<Member> getMembers() throws Exception;

 }

MemberService

3、服务实现 MemberServiceImpl

 package org.jboss.as.quickstart.hibernate4.service;

 import java.util.logging.Logger;
 import java.util.List;
 import javax.ejb.Stateless;
 import javax.enterprise.event.Event;
 import javax.inject.Inject;
 import javax.persistence.EntityManager;
 import javax.persistence.PersistenceContext;
 import org.jboss.as.quickstart.hibernate4.model.Member;

 @Stateless
 public class MemberServiceImpl implements MemberService {

     @PersistenceContext
     private EntityManager em;

     @Inject
     private Logger log;

     @Inject
     private Event<Member> memberEventSrc;

     @Override
     public void addMember(Member member) throws Exception {
         log.info("addMember => " + member.toString());
         member.setId(null);
         em.persist(member);
         memberEventSrc.fire(member);
     }

     @Override
     public void updateMember(Member member) throws Exception {
         log.info("updateMember => " + member.getName());
         if (member.getId() > 0) {
             Member updateObj = findMember(member.getId());
             updateObj.setAddress(member.getAddress());
             updateObj.setEmail(member.getEmail());
             updateObj.setName(member.getName());
             updateObj.setPhoneNumber(member.getPhoneNumber());
             em.merge(updateObj);
             memberEventSrc.fire(updateObj);
         }

     }

     @Override
     public void deleteMember(long id) throws Exception {
         log.info("deleteMember => " + id);
         Member member = findMember(id);
         em.remove(member);
         memberEventSrc.fire(member);

     }

     @Override
     public List<Member> getMembers() throws Exception {
         @SuppressWarnings("unchecked")
         List<Member> members = em.createQuery("from Member").getResultList();
         return members;

     }

     @Override
     public Member findMember(long id) throws Exception {
         log.info("findMember => " + id);
         return em.find(Member.class, id);
     }

 }

MemberService

注意：此外大量使用了CDI来实现对象的依赖注入，@PersistenceContext 用于在EJB容器中自动注入"实体管理器"（所以类上要使用@Stateless表示，这是一个无状态的EJB），上面这段代码演示了数据的基础CRUD(Create、Retrieve、Update、Delete)操作，另外为了配合CDI的@Inject注入，还需要一些@Produces的辅助工具类。(对CDI不熟悉的，可以先看看这里http://www.cnblogs.com/yjmyzz/p/j2ee-cdi-inject.html)

4、辅助类 Resouces

 package org.jboss.as.quickstart.hibernate4.util;

 import java.util.Map;
 import java.util.logging.Logger;
 import javax.enterprise.context.RequestScoped;
 import javax.enterprise.inject.Produces;
 import javax.enterprise.inject.spi.InjectionPoint;
 import javax.faces.context.FacesContext;

 public class Resources {

     @Produces
     public Logger produceLog(InjectionPoint injectionPoint) {
         return Logger.getLogger(injectionPoint.getMember().getDeclaringClass()
                 .getName());
     }

     @Produces
     @RequestScoped
     public FacesContext produceFacesContext() {
         return FacesContext.getCurrentInstance();
     }

     @Produces
     @RequestScoped
     public Map<String, String> getRequestParameterMap(){
         return FacesContext.getCurrentInstance().getExternalContext()
                 .getRequestParameterMap();
     } 

 }

Resources

注：该类主要用@Produces提供了CDI注入对象的实例化方法。

5、web层的Controller：MemberController

 package org.jboss.as.quickstart.hibernate4.controller;

 import java.util.List;
 import java.util.Map;

 import javax.annotation.PostConstruct;
 import javax.enterprise.inject.Model;
 import javax.enterprise.inject.Produces;
 import javax.faces.application.FacesMessage;
 import javax.faces.context.FacesContext;
 import javax.inject.Inject;
 import javax.inject.Named;

 import org.jboss.as.quickstart.hibernate4.model.Member;
 import org.jboss.as.quickstart.hibernate4.service.MemberService;

 @Model
 public class MemberController {

     @Inject
     MemberService service;

     @Inject
     private FacesContext facesContext;

     @Inject
     private Map<String, String> requestMap;

     private Member newMember;

     @Produces
     @Named
     public Member getNewMember() {
         return newMember;
     }

     @Produces
     @Named
     public List<Member> getMembers() {
         List<Member> members = null;
         try {
             members = service.getMembers();

         } catch (Exception e) {
             String errorMessage = getRootErrorMessage(e);
             facesContext.addMessage(null, new FacesMessage(
                     FacesMessage.SEVERITY_ERROR, errorMessage,
                     "Delete unsuccessful"));
         }
         return members;
     }

     public void deleteMemberById() {
         try {
             String id = requestMap.get("id");
             service.deleteMember(Long.parseLong(id));

         } catch (Exception e) {
             String errorMessage = getRootErrorMessage(e);
             facesContext.addMessage(null, new FacesMessage(
                     FacesMessage.SEVERITY_ERROR, errorMessage,
                     "Delete unsuccessful"));
         }

     }

     public void findMemberById() {
         try {
             String id = requestMap.get("id");
             newMember = service.findMember(Long.parseLong(id));
         } catch (Exception e) {
             String errorMessage = getRootErrorMessage(e);
             facesContext.addMessage(null, new FacesMessage(
                     FacesMessage.SEVERITY_ERROR, errorMessage,
                     "Find Member unsuccessful"));
         }

     }

     public void register() {
         try {
             if (newMember.getId() > 0) {
                 service.updateMember(newMember);
                 facesContext.addMessage(null, new FacesMessage(
                         FacesMessage.SEVERITY_INFO, "Updated!",
                         "Update successful"));
             } else {
                 service.addMember(newMember);
                 facesContext.addMessage(null, new FacesMessage(
                         FacesMessage.SEVERITY_INFO, "Registered!",
                         "Registration successful"));
             }
             initNewMember();
         } catch (Exception e) {
             String errorMessage = getRootErrorMessage(e);
             facesContext.addMessage(null, new FacesMessage(
                     FacesMessage.SEVERITY_ERROR, errorMessage,
                     "Save unsuccessful"));
         }
     }

     @PostConstruct
     public void initNewMember() {
         newMember = new Member();
     }

     private String getRootErrorMessage(Exception e) {
         String errorMessage = "Registration failed. See server log for more information";
         if (e == null) {
             return errorMessage;
         }

         Throwable t = e;
         while (t != null) {

             errorMessage = t.getLocalizedMessage();
             t = t.getCause();
         }

         return errorMessage;
     }

 }

MemberController

6、UI界面index.xhtml

 <?xml version="1.0" encoding="UTF-8"?>
 <ui:composition xmlns="http://www.w3.org/1999/xhtml"
     xmlns:ui="http://java.sun.com/jsf/facelets"
     xmlns:f="http://java.sun.com/jsf/core"
     xmlns:h="http://java.sun.com/jsf/html"
     template="/WEB-INF/templates/default.xhtml">
     <ui:define name="content">
         <h:form id="reg">
             <h2>Member Registration</h2>

             <h:panelGrid columns="3" width="100%" columnClasses="titleCell">
                 <h:inputHidden value="#{newMember.id}" id="id" />
                 <h:outputLabel for="name" value="Name:" />
                 <h:inputText id="name" value="#{newMember.name}" />
                 <h:message for="name" errorClass="invalid" />

                 <h:outputLabel for="email" value="Email:" />
                 <h:inputText id="email" value="#{newMember.email}" />
                 <h:message for="email" errorClass="invalid" />

                 <h:outputLabel for="phoneNumber" value="Phone #:" />
                 <h:inputText id="phoneNumber" value="#{newMember.phoneNumber}" />
                 <h:message for="phoneNumber" errorClass="invalid" />

                 <h:outputLabel for="address" value="Address:" />
                 <h:inputText id="address" value="#{newMember.address}" />
                 <h:message for="address" errorClass="invalid" />
             </h:panelGrid>

             <h:panelGrid columns="2">
                 <h:commandButton id="register" action="#{memberController.register}"
                     value="Register" styleClass="register" />
                 <h:messages styleClass="messages" errorClass="invalid"
                     infoClass="valid" warnClass="warning" globalOnly="true" />
             </h:panelGrid>

         </h:form>
         <h2>Members</h2>
         <h:panelGroup rendered="#{empty members}">
             <em>No registered members.</em>
         </h:panelGroup>
         <h:dataTable var="_member" value="#{members}"
             rendered="#{not empty members}" styleClass="simpletablestyle">
             <h:column>
                 <f:facet name="header">Id</f:facet>
                 #{_member.id}
             </h:column>
             <h:column>
                 <f:facet name="header">Name</f:facet>
                 #{_member.name}
             </h:column>
             <h:column>
                 <f:facet name="header">Email</f:facet>
                 #{_member.email}
             </h:column>
             <h:column>
                 <f:facet name="header">Phone #</f:facet>
                 #{_member.phoneNumber}
             </h:column>
             <h:column>
                 <f:facet name="header">Address</f:facet>
                 #{_member.address}
             </h:column>
             <h:column>
                 <f:facet name="header">Operation</f:facet>
                 <h:form style="border:none">
                     <h:commandLink action="#{memberController.deleteMemberById}"
                         value="delete">
                         <f:param name="id" value="#{_member.id}"></f:param>
                     </h:commandLink>|
                 <h:commandLink action="#{memberController.findMemberById}"
                         value="update">
                         <f:param name="id" value="#{_member.id}"></f:param>
                     </h:commandLink>
                 </h:form>
             </h:column>
         </h:dataTable>
     </ui:define>
 </ui:composition>

index.xhtml

7、persistence.xml 配置文件

 <?xml version="1.0" encoding="UTF-8"?>

 <persistence version="2.0"
     xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="
         http://java.sun.com/xml/ns/persistence
         http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
     <persistence-unit name="primary">
         <jta-data-source>java:/XE</jta-data-source>
         <mapping-file>META-INF/orm.xml</mapping-file>
         <properties>
             <property name="hibernate.hbm2ddl.auto" value="create-drop" />
             <property name="hibernate.show_sql" value="true" />
             <property name="hibernate.format_sql" value="true" />
             <property name="hibernate.use_sql_comments" value="true"/>
         </properties>
     </persistence-unit>
 </persistence>

persistence.xml

注：该文件位于src/main/resources/META-INF/目录下。java:/XE 是Jboss上配置好的一个数据源JNDI字符串。hibernate.hbm2ddl.auto属性值为create-drop，表明webapp启动时，会自动在db中创建表、序列对象，webapp停止时这些对象会自动drop

8、db初始化脚本 import.sql （测试的时候十分有用）

 insert into MemberHibernate4Demo (id, name, email, phone_number, address) values (SEQ_MEMBER.NEXTVAL, 'John Smith', 'john.smith@mailinator.com', '2125551212', 'Boston NY')
 insert into MemberHibernate4Demo (id, name, email, phone_number, address) values (SEQ_MEMBER.NEXTVAL, 'Madhumita Sadhukhan', 'msadhukh@gmail.com', '2135551214', 'Brno CZ')

import.sql

注：该文件位于src/main/resources目录下，webapp启用时将自动执行该文件中的db 脚本

9、其它运行准备：
9.1 要有Oracle Database环境，比如本机可以安装一个Express版本

9.2 Jboss中要配置一个java:/XE的数据源，步骤:

a) 先部署ojdbc6.jar （这是oracle驱动，安装oracle XE或client后，本机安装目录下就能找到）

b) 添加oracle 数据源，数据库驱动选择ojdbc6.jar，连接串参考 jdbc:oracle:thin:@localhost:1521:XE

示例程序下载：http://files.cnblogs.com/yjmyzz/jboss-jpa-sample.zip

运行截图：