teacher.java

jboss4 + Mysql +ejb3.0 EJB3 简单例子

/**
 * Copyright (c)上海烟草(集团)公司与上海康时信息系统有限公司。
 */
package com.myejb.entity;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;

/**
 * 
 * @author xywang
 * @since 2009-2-13
 * @version 1.0
 * 
 */
@SuppressWarnings("serial")
@Entity
@Table(name="Teacher")
public class Teacher implements Serializable{
    private Integer teacherid;
    private String TeacherName;
    private Set<Student> students = new HashSet<Student>();
    public Teacher(){
    }
    public Teacher(String teachername){
        this.TeacherName = teachername;
    }
    /**
     * 数据表关系：@JoinTable描述了多对多关系的数据表关系。name:指定中间表名称，joinColumns:定义中间表与Teacher表的外键关系。
     * inverseJoinColumns:定义了中间表与另外一端(Student)的外键关系。
     */
    @ManyToMany(cascade=CascadeType.PERSIST,fetch=FetchType.LAZY)
    @JoinTable(name="Teacher_Student",joinColumns={@JoinColumn(name="Teacher_ID",referencedColumnName="teacherid")},
            inverseJoinColumns={@JoinColumn(name="Student_ID",referencedColumnName="studentid")})
    public Set<Student> getStudents(){
        return students;
    }
    public void setStudents(Set<Student> students){
        this.students = students;
    }
    @Id
    @GeneratedValue
    public Integer getTeacherid(){
        return teacherid;
    }
    public void setTeacherid(Integer teacherid){
        this.teacherid = teacherid;
    }
    @Column(nullable=false,length=32)
    public String getTeacherName(){
        return TeacherName;
    }
    public void setTeacherName(String teacherName){
        TeacherName = teacherName;
    }
    public void addStudent(Student student){
        if(!this.students.contains(student)){
            this.students.add(student);
        }
    }
    public void removeStudent(Student student){
        this.students.remove(student);
    }
}