@Id
	@Column(length = 36, nullable = true)
	@GeneratedValue(generator = "uuid")
	@GenericGenerator(name = "uuid", strategy = "uuid2")
	public String getId() {
		return id;
	}
@ Id @ Column ( length = 36 , nullable = true ) @ GeneratedValue ( generator = "uuid" ) @ GenericGenerator ( name = "uuid" , strategy = "uuid2" ) public String getId ( ) { return id ; }
默认使用36位uuid作为主键

@return id