學生和老師就是多對多的關系。一個學生有多個老師,一個老師教多個學生。

  學生和檔案就是一對一的關系(不知道國外的學生 " /> 69免费视频,香蕉视频国产,亚洲天堂美女

四虎精品视频-四虎精品成人免费网站-四虎黄色网-四虎国产视频-国产免费91-国产蜜臀97一区二区三区

EJB3.0開發之多對多和一對一

在前面的例子中,我們演示了一對多和多對一的例子,在本章將演示多對多和一對一的關系。

  學生和老師就是多對多的關系。一個學生有多個老師,一個老師教多個學生。

  學生和檔案就是一對一的關系(不知道國外的學生有沒有檔案?)。

  為了實現多對多的關系,數據庫中需要關聯表,用以在兩個實體間建立關聯。JBoss可以自動生成關聯表,你也可以@AssociationTable來指定關聯表的信息。

  如:

  @ManyToMany(cascade = {CascadeType.CREATE, CascadeType.MERGE}, fetch = FetchType.EAGER, isInverse = true)
  @AssociationTable(table = @Table(name = "STUDENT_TEACHER"),

  joinColumns = {@JoinColumn(name = "TEACHER_ID")},inverseJoinColumns = {@JoinColumn(name = "STUDENT_ID")})

  @ AssociationTable的注釋聲明如下:
  @Target({METHOD, FIELD})

  public @interface AssociationTable {
  Table table() default @Table(specified=false);
  JoinColumn[] joinColumns() default {};
  JoinColumn[] inverseJoinColumns() default {};
  }

  關聯表注釋指定了關聯表的名稱、主表的列和從表的列。

  為了實現一對一的關系,需要用@ONEToOne來注釋。

  如:

  @ONEToOne(cascade = {CascadeType.ALL})
  @JoinColumn(name = "DOSSIER_ID")

  public Dossier getDossier()
  {
  return dossier;
  }

  這定義了一個單向的一對一的關系。如果在Dossier也定義了相關的關聯,那么它就是雙向的。雙向的意思就是通過一個Student實體就可以查找到一個Dossier,通過一個Dossier就可以查找到一個Student。

  @ ONEToOne的注釋聲明如下:
  @Target({METHOD, FIELD}) @Retention(RUNTIME)

  public @interface ONEToOne {
  String targetEntity() default "";
  CascadeType[] cascade() default {};
  FetchType fetch() default EAGER;
  boolean optional() default true;
  }

  這個例子主要有以下幾個文件,這個例子主要實現了學生和老師、學生和檔案之間的關系。Student、Teacher、Dossier都是實體Bean。Student和Dossier是一個雙向的ONEToOne之間的關系,Student和Teacher是ManyToMany的關系,也是雙向的。和前面的例子一樣,我們還是使用Client測試。

  Student.Java:實體Bean。

  Dossier.Java:實體Bean所依賴的類。

  Teacher.Java:實體Bean所依賴的類。

  EntityTest.Java:會話Bean的業務接口

  EntityTest Bean.Java:會話Bean的實現類

  Client.Java:測試EJB的客戶端類。

  jndi.properties:jndi屬性文件,提供訪問jdni的基本配置屬性。

  Build.xml:ant 配置文件,用以編譯、發布、測試、清除EJB。

  下面針對每個文件的內容做一個介紹。

  Student.Java

  package com.kuaff.ejb3.relationships;
  import Javax.ejb.CascadeType;
  import Javax.ejb.Entity;
  import Javax.ejb.FetchType;
  import Javax.ejb.GeneratorType;
  import Javax.ejb.Id;
  import Javax.ejb.JoinColumn;
  import Javax.ejb.ONEToOne;
  import Javax.ejb.ManyToMany;
  import Javax.ejb.Table;
  import Javax.ejb.AssociationTable;
  import Java.util.ArrayList;
  import Java.util.Set;
  import Java.util.Collection;
  import Java.io.Serializable;

  @Entity

  @Table(name = "STUDENT")

  public class Student implements Serializable

  {
  private int id;
  private String first;
  private String last;
  private Dossier dossier;
  private Set teachers;

  @Id(generate = GeneratorType.AUTO)

  public int getId()
  {
  return id;
  }

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

  public void setFirst(String first)
  {
  this.first = first;
  }

  public String getFirst()
  {
  return first;
  }

  public void setLast(String last)
  {
  this.last = last;
  }

  public String getLast()
  {
  return last;
  }

  public void setDossier(Dossier dossier)
  {
  this.dossier = dossier;
  }

  @ONEToOne(cascade = {CascadeType.ALL})
  @JoinColumn(name = "DOSSIER_ID")

  public Dossier getDossier()
  {
  return dossier;
  }

  public void setTeacher(Set teachers)
  {
  this.teachers = teachers;
  }

  @ManyToMany(cascade = {CascadeType.CREATE, CascadeType.MERGE}, fetch = FetchType.EAGER, isInverse = true)
  @AssociationTable(table = @Table(name = "STUDENT_TEACHER"),

  joinColumns = {@JoinColumn(name = "TEACHER_ID")},inverseJoinColumns = {@JoinColumn(name = "STUDENT_ID")})

  public Set getTeacher()
  {
  return teachers;
  }
  }

  Dossier.Java

  package com.kuaff.ejb3.relationships;

  import Javax.ejb.Entity;
  import Javax.ejb.GeneratorType;
  import Javax.ejb.Id;

  @Entity

  public class Dossier implements Java.io.Serializable
  {
  private Long id;
  private String resume;

  @Id(generate = GeneratorType.AUTO)
  public Long getId()
  {
  return id;
  }

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

  public void setResume(String resume)
  {
  this.resume = resume;
  }

  public String getResume()
  {
  return resume;
  }
  }

  Teacher.Java

  package com.kuaff.ejb3.relationships;

  import Javax.ejb.AssociationTable;
  import Javax.ejb.Basic;
  import Javax.ejb.CascadeType;
  import Javax.ejb.Column;
  import Javax.ejb.Entity;
  import Javax.ejb.FetchType;
  import Javax.ejb.Id;
  import Javax.ejb.JoinColumn;
  import Javax.ejb.ManyToMany;
  import Javax.ejb.Table;
  import Javax.ejb.Transient;
  import Javax.ejb.Version;
  import Java.util.Set;
  import Javax.ejb.GeneratorType;

  @Entity

  public class Teacher implements Java.io.Serializable
  {
  private Long id;
  private String resume;
  private String name;
  private String info;
  private Set students;

  @Id(generate = GeneratorType.IDENTITY)

  public Long getId()
  {
  return id;
  }

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

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

  public String getName()
  {
  return name;
  }

  public void setInfo(String info)
  {
  this.info = info;
  }

  public String getInfo()
  {
  return info;
  }

  public void setStudents(Set students)
  {
  this.students = students;
  }

  @ManyToMany(cascade = {CascadeType.CREATE, CascadeType.MERGE}, fetch = FetchType.EAGER)
  @AssociationTable(table = @Table(name = "STUDENT_TEACHER"),

  joinColumns = {@JoinColumn(name = "TEACHER_ID",referencedColumnName="ID")},
  inverseJoinColumns = {@JoinColumn(name = "STUDENT_ID",referencedColumnName="ID")})

  public Set getStudents()
  {
  return students;
  }
  }

  EntityTest.Java

  package com.kuaff.ejb3.relationships;

  import Javax.ejb.Remote;
  import Java.util.List;

  @Remote

  public interface EntityTest
  {
  public void createData();
  public List findByName(String name);
  }

  EntityTestBean.Java
  
  package com.kuaff.ejb3.relationships;

  import Javax.ejb.EntityManager;
  import Javax.ejb.Inject;
  import Javax.ejb.Stateless;
  import Java.util.HashSet;
  import Java.util.Set;
  import Java.util.List;

  @Stateless

  public class EntityTestBean implements EntityTest
  {
  private @Inject EntityManager manager;
  public void createData()
  {
  Teacher teacher1 = new Teacher();
  Teacher teacher2 = new Teacher();

  Set students1 = new HashSet();
  Set students2 = new HashSet();
  Student student1 = new Student();
  Student student2 = new Student();
  Student student3 = new Student();

  Dossier dossier1 = new Dossier();
  Dossier dossier2 = new Dossier();
  Dossier dossier3 = new Dossier();
  teacher1.setId(new Long(1));
  teacher1.setName("hushisheng");
  teacher1.setInfo("胡時勝教授,博士生導師");
  manager.create(teacher1);
  teacher2.setId(new Long(2));
  teacher2.setName("liyongchi");
  teacher2.setInfo("李永池教授,博士生導師");
  manager.create(teacher2);

  student1.setFirst("晁");
  student1.setLast("岳攀");
  dossier1.setResume("這是晁岳攀的檔案");
  student1.setDossier(dossier1);
  students1.add(student1);

  student2.setFirst("趙");
  student2.setLast("志偉");
  dossier2.setResume("這是趙志偉的檔案");
  student2.setDossier(dossier2);
  students1.add(student2);

  student3.setFirst("田");
  student3.setLast("明");

  dossier3.setResume("這是田明的檔案");
  student3.setDossier(dossier3);
  students2.add(student3);

  teacher1.setStudents(students1);
  teacher2.setStudents(students2);

  }

  public List findByName(String name)
  {
  return manager.createQuery("from Teacher t where t.name = :name").setParameter("name", name).listResults();
  }

  }

  在這個會話Bean中提供了創建各個實體Bean的方法,并提供了查找老師的方法。

  Client.Java

  package com.kuaff.ejb3.secondary;

  import Javax.naming.InitialContext;
  import Javax.naming.NamingException;
  import Java.util.List;

  public class Client
  {
  public static void main(String[] args) throws NamingException
  {
  InitialContext ctx = new InitialContext();
  StudentDAO dao = (StudentDAO) ctx.lookup(StudentDAO.class.getName());
  int id = dao.create("晁","岳攀","8","smallnest@kuaff.com","男");
  dao.create("朱","立煥","6","zhuzhu@kuaff.com","女");
  List list = dao.findAll();
  for(Object o:list)
  {
   Student s = (Student)o;
   System.out.printf("%s%s的性別:%s%n",s.getName().getFirst(),s.getName().getLast(),s.getGender());
   dao.evict(s);
  }
  }
  }

  這個客戶端用來測試。

  請運行{$JBOSS_HOME}/bin目錄下的run.bat: run 主站蜘蛛池模板: 我的碧可动画| 文熙俊| 黑玫瑰演员表| 性感的秘书| 影片《边境》| 最新电影在线| 搜狐网站官网| 惊天十二小时| department什么意思| 屁屁视频| 李雪琴个人资料及简历| 房子传| 3d成人国产同人动漫焰灵姬| 女性私密整形| 公司辞退员工的合法流程及赔偿 | 王牌特派员| 小镇姑娘高清在线观看| 我们的日子演员表| 稻草人三年级课外阅读| 舞出我的人生| 08版包青天狸猫换太子| 汤唯和梁朝伟拍戏原版视频在线观看| 双修杨幂,刘亦菲小说| 肢体的诱惑电影| 祈今朝电视剧免费观看完整版| 亲密 电影| 今日航班一览表| 西游记tvb| 我的新学校英语作文| a面b面| 护航电影| 幼儿园老师锦旗赠言| 《完美无瑕》莫妮卡贝鲁奇| 情欲网站| 风花电影完整版免费观看| 视频爱爱| freexxxmovies| 韶山研学心得体会800高中| 朱莉娅·安最经典十部电影| 康斯但丁| 即便如此我依然爱着我的老婆|