如何将 JSON 对象部分解析为 Java 对象

Question

I am working on a big json output file which is coming as response but I want to parse only some of the fields in my logic.

For ex: The JSON looks like this

{
 "lastName":"Smith",
"address":{
    "streetAddress":"21 2nd Street",
     "city":"New York",
     "state":"NY",
     "postalCode":10021
},
 "age":25,
 "phoneNumbers":[
        {
        "type":"home", "number":"212 555-1234"
        },
     {
        "type":"fax", "number":"212 555-1234"
     }
 ],
 "firstName":"John"
}

I have created the necessary JAVA classes and mapping the JSON Object to Java object using GSON . Since, the above JSON is just a sample one in my case I have big one which is generating around 15 classes.

Currently i have to create following classes files:

- Employee.class
- Address.class
- PhoneNumber.class

I want to avoid creating PhoneNumber.class and its nested class using GSON.

Basically My query is like in above json I don't want phoneNumbers and its internal objects so how can i ignore those fields so that i have to construct less Java Class files and still it is mapped to Java Object .

So I want to avoid making classes for PhoneNumbers fields and the nested fields inside PhoneNumbers.

Answer 1

As suggested, Employee and Address classes are all you need:

public class Employee {
    private String firstName, lastName;
    private int age;
    private Address address;
}

public class Address {
    private String streetAddress, city, state;
    private int postalCode;
}

new Gson().fromJson(json, Employee.class); , where json is the raw JSON string, should then do what you want. Without sharing your code, it is hard to tell why it doesn't work for you.