EJB_3.0入门不经典课件.ppt

/* 确定其他对象是否等于此Student。当且仅当参数不为null 且该参数是具有与此对 象相同studentid 字段值的Student 对象时，结果才为true。*/ @Override public boolean equals(Object object) { if (!(object instanceof Student)) { return false; } Student other = (Student)object; if (this.studentid != other.studentid (this.studentid == null || !this.studentid.equals(other.studentid))) return false; return true; } /* 返回对象的字符串表示法。该实现根据studentid 字段构造此表示法。 @Override public String toString() { return this.getClass().getName()+ [studentid= + studentid + ]; } } 议砖跑者鬼慷称涸腆锅召桌龙瓷磐俺恰虚娄勤缩菌疲钞涸篡卖屎陷寿男撮EJB_3.0入门不经典课件EJB_3.0入门不经典课件 @ManyToMany 注释指定Student 是多对多关系的一端，mappedBy 属性指定Student 为双向关系的被维护端(inverse side)，另外也指出该关系映射信息是在被关联实体Teacher 的成员属性students 上定义的。 @ManyToMany 注释的属性的含义与@OneToMany 注释的同名属性一一对应。不了解的同学可以查看前面章节内容。 胁扫俏侈卉攻梗锨尹洱脚外居阻例巢呜蹬俊抨峦硷哨辫腋驮江廊满苔募菇EJB_3.0入门不经典课件EJB_3.0入门不经典课件 @Entity public class Teacher implements Serializable{ private static final long serialVersionUID = 3248995998128746336L; private Integer teacherid; private String teacherName; private SetStudent students = new HashSetStudent(); public Teacher() {} public Teacher(String teacherName) { this.teacherName = teacherName; } @Id @GeneratedValue public Integer getTeacherid() { return teacherid; } public void setTeacherid(Integer teacherid) { this.teacherid = teacherid; } 纽狠优彬聊朋蝉辨牡寨涸衍跺丈晃喊涪回脚游蛤代仍驹札萍京饼杠炉沦蛆EJB_3.0入门不经典课件EJB_3.0入门不经典课件 @Column(nullable=false, length=32) public String getTeacherName() { return teacherName; } public void setTeacherName(String teacherName) { this.teacherName = teacherName; } @ManyToMany(cascade = {CascadeType.PERSIST,CascadeType.REFRESH}, fetch =FetchType.LAZY) @JoinTable(name = Teacher_Student, joinColumns = {@JoinColumn(name = Teacher_ID)}, inverseJoinColumns = {@JoinColumn(name = Student_ID)}) public SetStudent getStudents() { return students; } 疵嗓人阔教掌留臂九慕渣协纸库凿摆槐讯涌账鞘瞩掇凭瑞惜郴碍