Cut the json string in to two different json string in java

Question

I am pretty new to json and normally donot use do much coding. I want a service which takes below json string as input

{
    "var": "test11",
    "_env": {
        "activation": "wm6a93e3a80-0307-12cc-96e6-d79883bf841a",
        "uuid": "48cdc2d0-0212-11e6-8315-d79883bf841a",
        "eventID": 49167,
        "recvTime": "Thu Apr 14 00:27:03 PDT 2016"
    }
}

and spit out output as

{
    "var": "test11"
} 

and

{
    "_env": {
        "activation": "wm6a93e3a80-0307-12cc-96e6-d79883bf841a",
        "uuid": "48cdc2d0-0212-11e6-8315-d79883bf841a",
        "eventID": 49167,
        "recvTime": "Thu Apr 14 00:27:03 PDT 2016"
    }
}

The is just an example. It can contain more objects in json string and _env won't always appear at the end.

Is there any simple way to achieve using jackson API ?

Answer 1

Create a class to hold your JSON, like below:

public class Bar {

    private String var;

    @JsonProperty("_env")
    private Object env;

    public String getVar() {
        return var;
    }

    public void setVar(String var) {
        this.var = var;
    }

    public Object getEnv() {
        return env;
    }

    public void setEnv(Object env) {
        this.env = env;
    }
}

And set the mapper to not fail on unknown properties before deserializing;

public static void main(String[] argv) throws Exception {
    ObjectMapper mapper = new ObjectMapper();
    mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

    Bar bar = mapper.readValue(JSON, Bar.class);

}

This way, both when the _env is present or not, it will work.

If you need to "split" the json by each node, you can do something like this:

JsonNode node = mapper.readTree(JSON);
List<String> nodeJsons = new ArrayList<>();
Iterator<Entry<String, JsonNode>> nodeIterator = node.fields();
while (nodeIterator.hasNext()) {
    Map.Entry<String, JsonNode> entry = nodeIterator.next();
    nodeJsons.add(mapper.writeValueAsString(entry));
}

This way you will have a list of json strings in the end with every node serialized by itself, instead of one "big" json with everything.