如何使用 Jackson 的 ObjectMapper 从 JSON 字符串创建 object？

Question

I have classes structured in the following way:

@JsonRootName("class1")
public class class1 {
    private interface1 foo;

    public interface1 getFoo() {
        return foo;
    }

    public void setFoo(interface1 foo) {
        this.foo = foo;
    }
}

@JsonTypeInfo(include = JsonTypeInfo.As.WRAPPER_OBJECT, use = JsonTypeInfo.Id.NAME)
@JsonSubTypes({@JsonSubTypes.Type(value = class2.class, name = "class2")})
public interface interface1 {
    String getType();
}

@JsonTypeName("class2")
public class class2 implements interface1 {
    private String buzz = "bar";

    @Override
    public String getType() {
        return "class2";
    }

    public String getBuzz() {
        return buzz;
    }

    public void setBuzz(String buzz) {
        this.buzz = buzz;
    }
}

If I parsed the following JSON into class1 using the ObjectMapper it would be fine:

{
    "class1": {
        "foo": {
            "class2": {
                "buzz": "not bar"
            }
        }
    }
}

In this example the buzz variable in the class2 object would be set to "not bar" and the foo variable in the class1 would be set to the class2 object.

If I didn't want to modify the buzz variable in class2 and just wanted the foo variable in class1 to be set to a plain class2 object, how would I do that? The following doesn't work since "class2" is interpreted as a string:

{
    "class1": {
        "foo": "class2"
    }
}

Answer 1

Same as the first example, but without the buzz field.

{
    "class1": {
        "foo": {
            "class2": {
            }
        }
    }
}