@Id 注释是什么？

Question

我有一个class有这张便条，@Id，它有什么用？

package oknok.validacao.resources;

import org.jongo.marshall.jackson.oid.Id;

public class Validacao {

    @Id
    String id;
    String email;
    String instancia;
    String dataCriacao;
    String dataAtualizacao;

}

Answer 1

此注释将字段标记为 Mongo 文档标识符。

unique identifier available on every Mongo document. If it isn't setted, it is generated. To handle it with Jongo, one attribute has to be named _id or annotated with @Id (alias for @JsonProperty("_id"))

引自jongo spec

您可以阅读有关 Mongo 文档 ID here 的更多信息。

Answer 2

检查此 link： "Specifies the primary key of an entity. The field or property to which the Id annotation is applied should be one of the following types: any Java primitive type; any primitive wrapper type; String; java.util.Date; java.sql.Date; java.math.BigDecimal; java.math.BigInteger."

https://docs.oracle.com/javaee/6/api/javax/persistence/Id.html

@Id 注释是什么？

What does the @Id annotation?

java

annotations

mongodb

jongo