使用Spring Rest以自定义格式显示json

Question

I have a rest controller which returns JSON in some format but I want the JSON output in a different format .To implement the same I am using Spring REST.I have posted all model and controller classes below.My question is what could I do to get my expected response?

ACTUAL JSON

[
{
    "name": "CategoryName1",
    "sub": [
        {
            "name": "SubCategory1"
        },
        {
            "name": "SubCategory2"
        }
    ]
},
{
    "name": "CategoryName2",
    "sub": [
        {
            "name": "SubCategory3"
        },
        {
            "name": "SubCategory4"
        }
    ]
}

]

EXPECTED JSON

{
    "CategoryName1": ["SubCategory1", "SubCategory2"],
    "CategoryName2": ["SubCategory1", "SubCategory2"]
}

Category

public class Category{

public String name;
public List<Subcategory> sub;
public List<Subcategory> getSub() {
    return sub;
}

public void setSub(List<Subcategory> sub) {
    this.sub = sub;
}

public Category(String name) {
    super();
    this.name = name;
}

}

Subcategory

public class Subcategory{

public String name;

public Subcategory(String name) {
    super();
    this.name = name;
}

}

Controller

@RequestMapping(value = "/dropdown", method = RequestMethod.GET, produces = "application/json")
public @ResponseBody List<Category> dropdown() {
    Subcategory SubCategory1 = new  Subcategory("SubCategory1");
    Subcategory SubCategory2 = new  Subcategory("SubCategory2");
    Subcategory SubCategory3 = new  Subcategory("SubCategory3"); 
    Subcategory SubCategory4 = new  Subcategory("SubCategory4"); 

    Category CategoryName1 = new Category("CategoryName1");
    Category CategoryName2 = new Category("CategoryName2");

    List<Subcategory> subList = new ArrayList<Subcategory>();
    subList.add(SubCategory1);
    subList.add(SubCategory2);
    List<Subcategory> subList2 = new ArrayList<Subcategory>();
    subList2.add(SubCategory3);
    subList2.add(SubCategory4);

    CategoryName1.setSub(subList);
    CategoryName2.setSub(subList2);

    List<Category> cat = new ArrayList<Category>();
    cat.add(CategoryName1);
    cat.add(CategoryName2);

    return cat;
}

Answer 1

You can try like this :

public class Category {
    private Map<String, List<String>> response = new HashMap<>();
    Category(Map<String, List<String>> response){
    this.response = response;
   }
}

Usage: Fill data with Category object and return from rest api.

private Map<String, List<String>> response = new HashMap<>();
 List<String> list = new ArrayList<>();
 list.add("SubCategory1");
 list.add("SubCategory2");
 response.put("CategoryName1", list);
 response.put("CategoryName2", list);
 Category category = new Category(response);