java jsonobject“value”和“num”

Question

when using the javax json ObjectBuilder to build json, the output json string contains "value" and "num" in the json string. my web service is throw serialization error when the json contains "value" and "num". any one know why the output have "value" and "num"?

example:

JsonObject addProductRequest = Json.createObjectBuilder()
            .add("OrderID", orderId)
            .add("Product", productId)
            .add("Quantity", qty)
            .add("access_token", access_token)
            .build();

output:

{
  "OrderID": {
    "num": 15498
  },
  "ProductID": {
    "num": 20
  },
  "Quantity": {
    "num": 1
  },
  "access_token": {
    "value": "1f6c689d-6956-4f8e-b259-9030d57bec4b"
  }
}

when I switch to using google.gson.JsonObject, the output dont have the "value" and "num" string, which my web service accepts and every thing seems to work fine. example

 com.google.gson.JsonObject addProductRequest = new com.google.gson.JsonObject();
    addProductRequest.addProperty("OrderID", orderId);
    addProductRequest.addProperty("Product", productId);
    addProductRequest.addProperty("Quantity", qty);
    addProductRequest.addProperty("access_token", access_token);

output:

{  "OrderID": 15499,  "Product": 20,  "Quantity": 1,  "access_token": "3241cfd4-7b6c-4eac-b2bb-9b2b0c780831"}

Answer 1

Rest Assured seems to use Gson to serialize POJOs (which is what you should be using as response entities) to the response body.

Gson doesn't know anything about javax.json . The implementation of javax.json that you are using basically has this format for its JsonObject :

private static final class JsonObjectImpl extends AbstractMap<String, JsonValue> implements JsonObject {
    private final Map<String, JsonValue> valueMap;      // unmodifiable

Since this is a Map , Gson uses special serializing, iterating through its entrySet and using each Entry as a JSON key-value pair (within a JSON object).

In this case, the entrySet returns

@Override
public Set<Entry<String, JsonValue>> entrySet() {
    return valueMap.entrySet();
} 

where the valueMap contains all the values you added with add in your builder. For example, for

.add("OrderID", 1)

it will have added an entry with the String key OrderID and the JsonValue value of

// Optimized JsonNumber impl for int numbers.
private static final class JsonIntNumber extends JsonNumberImpl {
    private final int num;

Notice the num field.

So Gson will now see a value of this JsonIntNumber type. It considers it a POJO and so serializes it as a JSON object with its fields as key-value pairs. It therefore produces

{
    "num": 15498
}

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com.google.gson.JsonObject is a known type to Gson . It knows that it is special and not a custom POJO type. It can therefore write it directly, instead of having to serialize it further.

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This is similar to a question which I answered here:

• Returning JsonObject using @ResponseBody in SpringMVC