Book book = Book.builder()
                .id(20L)
                .author("Bob")
                .createTime(new Date())
                .build();

//序列化
String str = objectMapper.writeValueAsString(book);

//反序列化
Book book1 = objectMapper.readValue(str, Book.class);

//改变序列化顺序   
@JsonPropertyOrder(value={"content","title"})   
public class Book {

	//为空元素不做序列化
	@JsonInclude(JsonInclude.Include.NON_NULL)
	private Long id;

	//改变序列化/反序列化名字
	@JsonProperty("auther")
	private String author;

	private String title;

	private String content;           

	//定义序列化反序列化时间格式
	@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
	private Date createTime;

	private List<User> users;

}