java - 将 POJO 序列化为 JSON - 输入参数化

Question

我有 4 个 POJO ( links )

我有一个类文件，它将根据这些 POJO 映射值 ( Link )

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" } ] }

我不知道如何即兴编写代码来像我期望的那样打印输出，谢谢

预期:面糊、配料值也

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