将 POJO 序列化为 JSON - 输入参数化

Question

我有 4 个 POJO

我有一个类文件将根据这些 POJO 映射值

当我运行代码时

public static void main(String[] args) throws Exception {

    Input user = new Input();

    user.setId("0001");

    user.setType("donut");

    user.setName("cake");

    user.setPpu(0.55);

下面是我的输出

{

  "id" : "0001",

  "type" : "donut",

  "name" : "cake",

  "ppu" : 0.55,

  "batters" : null,

  "topping" : [ ]

}

但是，我希望我的输出是

{ "id": "0001", "type": "donut", "name": "Cake", "ppu": 0.55, "batters": 

{ "batter": [{ "id": "1001", "type": "Regular" }, 

{ "id": "1004", "type": "Devil's Food" } ] }, "topping": [{ "id": "5001", 

"type": "None" }, { "id": "5004", "type": "Maple" } ] }

我不确定如何即兴编写代码以像我期望的那样打印输出，谢谢

Answer 1

你应该使用这样的东西：public static void main(String[] args) throws Exception {    Input user = new Input();    user.setId("0001");    user.setType("donut");    user.setName("Cake");    user.setPpu(0.55);    // Add Regular batter    Batter batter1 = new Batter();    batter1.setId("0001");    batter1.setType("Regular");    // Add Devil's Food batter    Batter batter2 = new Batter();    batter2.setId("1004");    batter2.setType("Devil's Food");    Batters batters = new Batters();    batters.setBatter(Arrays.asList(batter1, batter2));    user.setBatters(batters);     // Add toppings    Topping topping1 = new Topping();    topping1.setId("5001");    topping1.setId("None");    Topping topping2 = new Topping();    topping2.setId("5004");    topping2.setId("Maple");    users.setTopping(Arrays.asList(topping1, topping2));    ObjectMapper mapper = new ObjectMapper();    mapper.enable(SerializationFeature.INDENT_OUTPUT);    String json = mapper.writeValueAsString(user);    System.out.println(json); // expected string

Answer 2

public static void main(String[] args) throws JsonProcessingException {    Javabelazy user = new Javabelazy();    user.setId("0001");    user.setType("donut");    user.setName("Cake");    user.setPpu("0.55");    Batter batter1 = new Batter();    batter1.setId("0001");    batter1.setType("Regular");    Batter batter2 = new Batter();    batter2.setId("1004");    batter2.setType("Devil's Food");    Batters batters = new Batters();    Batter[] batter = new Batter[2];    batter[1] = batter1;    batter[0] = batter2;    batters.setBatter(batter );    user.setBatters(batters);     Topping topping1 = new Topping();    topping1.setId("5001");    topping1.setId("None");    Topping topping2 = new Topping();    topping2.setId("5004");    topping2.setId("Maple");    Topping[] topping = new Topping[2];    topping[0] = topping1;    topping[1] = topping2;    user.setTopping(topping );    ObjectMapper objectmapper = new ObjectMapper();    String json = objectmapper.writeValueAsString(user);    System.out.println(json);}