用Jackson从String反序列化LocalDateTime
用Jackson从String反序列化LocalDateTime
提问于 2018-09-03 09:10:34
我试图用Jackson将一个String反序列化为LocalDateTime，但它不起作用。
我有一个带有LocalDateTime字段的数据类：
@Data
public class Registration {
@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd hh:mm:ss")
private LocalDateTime timestamp;
}我添加了特殊的Jackson数据类型模块：
compile("com.fasterxml.jackson.datatype:jackson-datatype-jsr310")序列化可以很好地处理：
new ObjectMapper().registerModule(new JavaTimeModule()).writeValueAsString(registration);结果字符串：
{"timestamp":"2018-09-03 10:09:35"}但是反序列化不适用于：
new ObjectMapper().registerModule(new JavaTimeModule()).readValue(json.traverse(), Registration.class)作为错误，我得到：
Cannot deserialize value of type `java.time.LocalDateTime` from String "2018-09-03 10:09:35":
Failed to deserialize java.time.LocalDateTime:
(java.time.format.DateTimeParseException) Text '2018-09-03 10:09:35' could not be parsed:
Unable to obtain LocalDateTime from TemporalAccessor:
{MinuteOfHour=9, NanoOfSecond=0, SecondOfMinute=35, MicroOfSecond=0, MilliOfSecond=0, HourOfAmPm=10},
ISO resolved to 2018-09-03 of type java.time.format.Parsed我遗漏了什么？我感到困惑的是，序列化可以工作，但反序列化却不能。
MWE: (小规模Java项目)
Main.java：
import java.io.IOException;
import java.time.LocalDateTime;
import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.core.TreeNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
public class Main {
public static void main(String[] args) throws IOException {
Registration registration = new Registration();
registration.setTimestamp(LocalDateTime.now());
ObjectMapper objectMapper = new ObjectMapper().registerModule(new JavaTimeModule());
String s = objectMapper.writeValueAsString(registration);
TreeNode treeNode = objectMapper.readTree(s);
//Fails here:
Registration registration1 = objectMapper.readValue(treeNode.traverse(), Registration.class);
System.out.println(registration1);
}
}
class Registration {
@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd hh:mm:ss")
private LocalDateTime timestamp;
public Registration() {
}
public LocalDateTime getTimestamp() {
return this.timestamp;
}
public void setTimestamp(LocalDateTime localDateTime) {
this.timestamp = localDateTime;
}
}build.gradle：
plugins {
id 'java'
}
group 'dateMWE'
version '1.0-SNAPSHOT'
sourceCompatibility = 10
repositories {
mavenCentral()
}
dependencies {
compile("com.fasterxml.jackson.core:jackson-annotations:2.9.6")
compile("com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.9.6")
}回答 2
Stack Overflow用户
回答已采纳
发布于 2018-09-03 09:39:22
问题与JSON反序列化无关，而是与时间格式字符串有关：
pattern = "yyyy-MM-dd hh:mm:ss"请注意，时间设置为hh：这是一个12小时的格式化程序，需要"AM“或"PM”值。
如果将模式更改为
pattern = "yyyy-MM-dd HH:mm:ss"这个问题应该解决。
Stack Overflow用户
发布于 2018-09-03 09:48:02
您的ObjectMapper不是按spring管理的，因为您正在使用新的对象创建对象。在配置文件中将ObjectMapper配置为Bean。您需要向您的DateTimeFormat注册LocalDateTimeDeserializer。然后在JavaTimeModule中设置反序列化器。
@Bean
public ObjectMapper objectMapper() {
JavaTimeModule module = new JavaTimeModule();
LocalDateTimeDeserializer localDateTimeDeserializer = new
LocalDateTimeDeserializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
module.addDeserializer(LocalDateTime.class, localDateTimeDeserializer);
ObjectMapper objectMapperObj = Jackson2ObjectMapperBuilder.json()
.modules(module)
.featuresToDisable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
.build();
return objectMapperObj;
}在Spring配置中设置上述配置。
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原文链接：
https://stackoverflow.com/questions/52146579
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