java - @DateTimeFormat 无法识别

Question

我正在尝试使用 @DateTimeFormat 注释 LocalDateTime 对象为什么它不识别它？

我的主要想法是，一旦 Controller 接收到一个字符串，它就会将其转换为 LocalDateTime 对象

目前我得到:

{
  "timestamp": 1493708443198,
  "status": 400,
  "error": "Bad Request",
  "exception": "org.springframework.http.converter.HttpMessageNotReadableException",
  "message": "Could not read JSON document: Can not construct instance of java.time.LocalDateTime: no String-argument constructor/factory method to deserialize from String value ('2015-09-26T01:30:00.000')\n at [Source: java.io.PushbackInputStream@3233297a; line: 5, column: 23] (through reference chain: net.petrikainulainen.spring.trenches.model.Topic[\"localDateTime\"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of java.time.LocalDateTime: no String-argument constructor/factory method to deserialize from String value ('2015-09-26T01:30:00.000')\n at [Source: java.io.PushbackInputStream@3233297a; line: 5, column: 23] (through reference chain: net.petrikainulainen.spring.trenches.model.Topic[\"localDateTime\"])",
  "path": "/api/topics"
}

尝试发帖时

 {
     "id": "javaw2",
     "name": "java code",
     "descript2ion": "java description",
     "localDateTime": "2015-09-26T01:30:00.000"
 }

这是我的 Controller :

@RequestMapping(method = RequestMethod.POST, value = "/topics")
public void addTopic(@RequestBody Topic topic) {
    topicService.addTopic(topic);
}

Answer 1

Can not construct instance of java.time.LocalDateTime: no String-argument constructor/factory method to deserialize from String value ('2015-09-26T01:30:00.000')

错误指出 LocalDateTime 类没有 String 参数构造函数/工厂方法，因此您必须编写自己的 反序列化器 将 Date 字符串表示反序列化为 LocalDateTime 对象。

类似的东西:

@JsonDeserialize(using = MyDateDeserializer.class)
private LocalDateTime localDateTime;

然后是MyDateDeserializer实现

public class MyDateDeserializer extends JsonDeserializer< LocalDateTime > {
  @Override
  public LocalDateTime deserialize(JsonParser jp, DeserializationContext ctxt) throws Exception {

    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("your pattern");

    String date = jp.getValueAsString();

    LocalDateTime localDateTime = LocalDateTime.parse(date, formatter);
    return localDateTime;
  }
}