java - 从 JSON 字符串构建 Spring ResponseEntity 对象

Question

我有一个 ResponseEntity.class 的有效 JSON 字符串。比如这个:

{
    "headers": {
        "Location": ["/v1/books/12345"]
    },
    "body": {
        "id": 12345,
        "type": "BOOK",
        "address": {
            "address": "Some address",
            "city": "Some city"
        }
    },
    "statusCode": "CREATED",
    "statusCodeValue": 201
}

我想从该字符串创建一个 ResponseEntity.class 对象。我为此使用标准 jackson 映射器:

objectMapper.readValue(jsonString, ResponseEntity.class)

并返回以下错误:

Can not construct instance of org.springframework.http.ResponseEntity: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?)

确实，当我检查该类时，我没有看到默认构造函数。我该如何解决问题并创建对象？

Answer 1

Jackson 需要一个无参数构造函数或元数据来引导它。请参阅http://www.cowtowncoder.com/blog/archives/2011/07/entry_457.html

要使其与 ResponseEntity 一起使用，您可能需要扩展 ResponseEntity，重新声明构造函数(委托(delegate)给 super)并按照 Jackson 的预期对它们进行注释.