java - Jackson反序列化错误: MismatchedInputException

Question

我有以下类(class)

public class Cart {
    private final String id;

    public Cart(String id) { this.id = id;}

    public String getId() { return id; }
}

以及以下测试:

    String jsonString = "{\"id\":\"56c7b5f7-115b-4cb9-9658-acb7b849d5d5\"}";
    Cart cart = mapper.readValue(jsonString, Cart.class);
    assertThat(cart.getId()).isEqualTo("56c7b5f7-115b-4cb9-9658-acb7b849d5d5");

我收到以下错误:

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of com.store.domain.model.Cart (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator) at [Source: (String)"{"id":"56c7b5f7-115b-4cb9-9658-acb7b849d5d5"}"; line: 1, column: 2]

我不明白这里出了什么问题。请问有什么帮助吗？

Answer 1

您应该添加一个不带任何参数的普通构造函数，如下所示:

public Cart() { }