Java 如何将json数据转换为嵌套json数据格式？

这是我在spring中使用list编写的输出，但我希望它采用嵌套的json格式，即树视图（结构），类似于下面的结构

[{"roleId":1,"roleName":"system Admin","createUser":"1","createActive":"N"},{"roleId":2,"roleName":"admin","createUser":"1","createActive":"Y"},{"roleId":3,"roleName":"system Admin","createUser":"1","createActive":"Y"}]

我的密码是

 [{ "id": 1, "data": "Category", "attr": { "id": "1", "selected": false }, "children":
                    [
                        { "id": 2, "data": "SubCategory1", "attr": { "id": "2", "selected": false }, "children":
                                [{ "id": 4, "data": "Item1", "attr": { "id": "4", "selected": false }, "children": [] },
                                 { "id": 5, "data": "Item2", "attr": { "id": "5", "selected": false }, "children": [] },
                                 { "id": 6, "data": "Item3", "attr": { "id": "6", "selected": false }, "children": [] }
                                ]
                        },

                        { "id": 3, "data": "SubCategory2", "attr": { "id": "3", "selected": false }, "children":
                                 [{ "id": 7, "data": "Item4", "attr": { "id": "7", "selected": false }, "children": [] },
                                  { "id": 8, "data": "Item5", "attr": { "id": "8", "selected": false }, "children": [] },
                                  { "id": 9, "data": "Item6", "attr": { "id": "9", "selected": false }, "children": [] }
                                 ]
                        }
                    ]
    }];

@GET
@路径（“/findall”）
公共列表getAll（）{
返回userroleservice.findAll（）；
}

将漂亮的打印与一些Json解析器（如Gson）结合使用

    @GET
    @Path("/findall")
    public List<UserRole> getAll() {

         return userroleservice.findAll();
    }

如果是在网页中，请使用javascript或

Gson gson = new GsonBuilder().setPrettyPrinting().create();
String json = gson.toJson(obj);
System.out.println(json);

var str = JSON.stringify(obj, null, 4);