我如何使用杰克逊JSON映射与Java 8 LocalDateTime?
jsonmappingexception:不能实例化类型[简单类型,java.time类]的值。LocalDateTime] from JSON字符串;没有单字符串构造函数/工厂方法(通过引用链:MyDTO["field1"]->SubDTO["date"])
我如何使用杰克逊JSON映射与Java 8 LocalDateTime?
jsonmappingexception:不能实例化类型[简单类型,java.time类]的值。LocalDateTime] from JSON字符串;没有单字符串构造函数/工厂方法(通过引用链:MyDTO["field1"]->SubDTO["date"])
当前回答
对于那些正在寻找ES-8和Spring Boot:3.0版本的解决方案的人
创建一个扩展ElasticsearchConfiguration的配置文件,并覆盖clientConfiguration和elasticsearchClient的创建。
在创建elasticsearchClient期间,注入您自己的配置为使用Java 8时间模块的objectMapper,它将覆盖默认的objectMapper。
@Override
public ClientConfiguration clientConfiguration() {
return ClientConfiguration.builder()
.connectedTo(<Hostname> +":"+ <Port>)
.usingSsl()
.withBasicAuth(<Username>, <Password>)
.build();
}
@Override
public ElasticsearchClient elasticsearchClient(RestClient restClient) {
Assert.notNull(restClient, "restClient must not be null");
//Create Java8 time module
JavaTimeModule module = new JavaTimeModule();
module.addSerializer(new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DateFormat.date_time_no_millis.getPattern())));
//Register the module with objectMapper
ObjectMapper objectMapper=new ObjectMapper()
.registerModule(module);
//To convert datetime to ISO-8601
objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
//Creating our own jsonpMapper
JsonpMapper jsonpMapper=new JacksonJsonpMapper(objectMapper);
// Create the transport with a Jackson mapper
ElasticsearchTransport transport = new RestClientTransport(
restClient, jsonpMapper);
// And create the API client
return new ElasticsearchClient(transport);
}
Maven的依赖:
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-jsr310</artifactId>
<version>2.14.0</version>
</dependency>
其他回答
如果有人在使用SpringBoot时遇到问题,这里是我在不添加新的依赖项的情况下修复问题的方法。
在Spring 2.1.3中,Jackson期望在此yyyy-MM-dd HH:mm:ss中出现日期字符串2019-05-21T07:37:11.000。在LocalDateTime中反序列化SSS格式。确保日期字符串用T分隔日期和时间,而不是用空格。秒(ss)和毫秒(SSS)可以省略。
@JsonProperty("last_charge_date")
public LocalDateTime lastChargeDate;
更新:由于历史原因,留下这个答案,但我不建议这样做。请参阅上面接受的答案。
告诉Jackson使用自定义的[反]序列化类进行映射:
@JsonSerialize(using = LocalDateTimeSerializer.class)
@JsonDeserialize(using = LocalDateTimeDeserializer.class)
private LocalDateTime ignoreUntil;
提供自定义类:
public class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> {
@Override
public void serialize(LocalDateTime arg0, JsonGenerator arg1, SerializerProvider arg2) throws IOException {
arg1.writeString(arg0.toString());
}
}
public class LocalDateTimeDeserializer extends JsonDeserializer<LocalDateTime> {
@Override
public LocalDateTime deserialize(JsonParser arg0, DeserializationContext arg1) throws IOException {
return LocalDateTime.parse(arg0.getText());
}
}
随机事实:如果我在类上面嵌套并且不使它们静态,错误消息是奇怪的: httpmediatypenotsupportedexception:内容类型'application/json;charset=UTF-8'不支持
这只是一个例子,如何使用它在一个单元测试,我黑调试这个问题。 关键成分是
mapper。registerModule(从新JavaTimeModule (); <artifactId>jack -datatyp -jsr310</artifactId>的maven dependency
代码:
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import org.testng.Assert;
import org.testng.annotations.Test;
import java.io.IOException;
import java.io.Serializable;
import java.time.Instant;
class Mumu implements Serializable {
private Instant from;
private String text;
Mumu(Instant from, String text) {
this.from = from;
this.text = text;
}
public Mumu() {
}
public Instant getFrom() {
return from;
}
public String getText() {
return text;
}
@Override
public String toString() {
return "Mumu{" +
"from=" + from +
", text='" + text + '\'' +
'}';
}
}
public class Scratch {
@Test
public void JacksonInstant() throws IOException {
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JavaTimeModule());
Mumu before = new Mumu(Instant.now(), "before");
String jsonInString = mapper.writeValueAsString(before);
System.out.println("-- BEFORE --");
System.out.println(before);
System.out.println(jsonInString);
Mumu after = mapper.readValue(jsonInString, Mumu.class);
System.out.println("-- AFTER --");
System.out.println(after);
Assert.assertEquals(after.toString(), before.toString());
}
}
我在使用Spring boot时遇到了类似的问题。 使用Spring启动1.5.1。我所要做的就是添加依赖项:
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-jsr310</artifactId>
</dependency>
我想为Spring的DurationStyle解析提供支持,在使用Jackson反序列化的自定义配置文件中的属性文件中提供支持,例如将20s序列化为Duration PT20S。我通过在ObjectMapper实例上注册一个自定义反序列化器来实现这一点:
@Bean("customConfigMapper")
public ObjectMapper customConfigMapper() {
final ObjectMapper mapper = new ObjectMapper();
final SimpleModule module = new SimpleModule();
module.addDeserializer(Duration.class, new SpringDurationStyleDeserializer());
mapper.registerModule(module);
return mapper;
}
public static class SpringDurationStyleDeserializer extends JsonDeserializer<Duration> {
@Override
public Duration deserialize(JsonParser jsonParser, DeserializationContext __) throws IOException {
return Optional.ofNullable(jsonParser.getText()).map(DurationStyle::detectAndParse).orElse(null);
}
}