Jackson-序列化时省略字段名称

Question

I have the following data:

{ long x; long y;}

Upon serialization to JSON using Jackson, I get the following:

{ "x": 1, "y": 2 }

However, I'm looking for this instead:

[1, 2]

How can I do that with Jackson?

Answer 1

As others have noted you can not omit keys for JSON Objects, but you could serialize POJO as an array like so:

@JsonFormat(shape=JsonFormat.Shape.ARRAY)
@JsonPropertyOrder({ "x", "y" }) // important; or 'alphabetic=true'
public class POJO {
   public int x, y;
}

which would then serialize as something like:

[1,2]

and even deserialize back from JSON Array similarly.

Answer 2

No, you're violating the JSON format which is essentially key-value format.

However you could serialise it as:

{
    values: [ 1, 2 ] 
}

Just make it a list in your dto.

Answer 3

{ 1, 2}

is not a valid JSON. Are you looking for [ 1,2] ? it's list or array. You can serialize

List<Long>

to it.