EJB3的JPA里@ManyToMany(多对多)的配置例子

一个博客，可以有多个附件，反过来，也允许一个附件属于多个博客(共享）
博客表：T_BLOG 主键ID
中间表：T_BLOG_ATTACHMENT( BLOGID,ATTACHMENT_ID) 就2个字段做联合主键
附件表：T_ATTACHMENT 主键ID

  @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
  @JoinTable(name = "T_BLOG_ATTACHMENT", joinColumns = @JoinColumn(name = "BLOG_ID", referencedColumnName = "ID"), inverseJoinColumns = @JoinColumn(name = "ATTACHMENT_ID", referencedColumnName = "ID"))
  private List<Attachment> attachments;