For a class similar to the following:

class A{
   @JsonProperty("hello_world")
   private String helloWorld;

   public String getHelloWorld(){...}
   public void setHelloWorld(String s){...}
}

When I try to convert it to a Json object via Obejct Mapper or GSON.

new ObjectMapper().writeValueAsString(object);
or
gson.toJson(object);

What I get is something like:

{
"helloWorld": "somevalue";
}

however I need to have the Json Property to be picked up like:

{
"hello_world": "somevalue"
}

I have looked around other similar questions, but none of them addresses this. Please help.

CodePudding user response：

Your approach is correct while using Jackson but it won't work for Gson, as you can't mix and match @JsonProperty between these two libraries.

If you'd like to use Jackson, then you can use @JsonProperty as shown in this example:

public class JacksonTest {
    @Test
    void testJackson() throws JsonProcessingException {
        String json = new ObjectMapper().writeValueAsString(new A("test"));
        Assertions.assertEquals(json, "{\"test_value\":\"test\"}");
    }
}
class A {
    @JsonProperty("test_value")
    private final String testValue;

    A(String testValue) {
        this.testValue = testValue;
    }

    public String getTestValue() {
        return testValue;
    }
}

However, if you'd prefer using Gson in your code, you'll need to replace @JsonProperty with @SerializedName annotation, as shown here:

public class GsonTest {

    @Test
    void testGson() {
        String json = new GsonBuilder().create().toJson(new B("test"));
        Assertions.assertEquals(json, "{\"test_value\":\"test\"}");
    }
}
class B {
    @SerializedName("test_value")
    private final String testValue;

    B(String testValue) {
        this.testValue = testValue;
    }

    public String getTestValue() {
        return testValue;
    }
}

Hope it helps.

CodePudding user response：

for me it works good, I use your A object and my code is:

A a = new A();
a.setHelloWorld("laalmido");
String s = new com.fasterxml.jackson.databind.ObjectMapper().writer().withDefaultPrettyPrinter().writeValueAsString(a);
System.out.println("json = "   s);

And the output is:

json = { "hello_world" : "laalmido" }