mongo-java-driver如何使用字符串ID反射ObjectId

Question

in mongodb：

{ 
"_id" : ObjectId("5a1e8e10cf40cb2b6b08112f")
}

in C#, i can use this (ps:i need to setting string ID,not ObjectID)

[BsonIgnoreExtraElements]
    public class ElapsedTimeLog : IEntity<string>
    {
        /// <summary>
        /// 主键ID
        /// </summary>
        [BsonId]
        [BsonRepresentation(BsonType.ObjectId)]
        public string ID { get; set; }
     }

but in java，i don't know how to do, i didn't found @BsonRepresentation or like something

when i write like this, it error

public class User_ObjectID implements EntityStringKey {
    //
    @BsonId
    private String id;

    //#region 
    public String getId(){return id;}

    public void setId(String id){this.id = id;}
    //#endregion
}

Error Message： An exception occurred when decoding using the AutomaticPojoCodec. Decoding into a 'User_ObjectID' failed with the following exception:

Failed to decode '_id'. readString can only be called when CurrentBSONType is STRING, not when CurrentBSONType is OBJECT_ID.

A custom Codec or PojoCodec may need to be explicitly configured and registered to handle this type.

Answer 1

Instead of using String for id, You need to use ObjectId class. This class maps _id of mongoDB to Java

private ObjectId id;

After Getting the object, you can get the _id String by -

id.toString();