我正在尝试使用 fasterxml jackson 将具有 java.util.Date 字段的 java 对象持久化到 mongo 集合中。
问题是 objectMapper 的默认行为是将 Date 存储为 NumberLong 类型。
例如，java.util.Date 类型的 createdTime 字段被存储如下：
"createdTime" : NumberLong("1427728445176")
我想要将其存储为 mongo Shell 中可用的 ISODate 格式。
现在，我知道有一种方法可以格式化 object mapper 以将日期存储为字符串日期格式。但是我只想要使用 ISODate() 格式。
例如：
"createdTime" : ISODate("2015-01-20T16:39:42.132Z")
是否有办法实现这一点？ 请高人指点。 提前感谢您的帮助。
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JodaModule());
mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, true);
mapper.writeValueAsString(date);
您可以根据需要将上面代码示例中的date替换为您的POJO。
编辑：看起来您真正想要的是自定义序列化器。它可能如下所示：
public class IsoDateSerializer extends JsonSerializer<DateTime> {
@Override
public void serialize(DateTime value, JsonGenerator jgen, SerializerProvider provider) {
String isoDate = ISODateTimeFormat.dateTime().print(value);
jgen.writeRaw("ISODATE(\"" + isoDate + "\")");
}
然后你要将所有的日期时间类型都在映射器上注册
mapper.addSerializer(DateTime.class, new IsoDateSerializer());
或在函数中使用注释来指定它
@JsonSerializer(using = IsoDateSerializer.class)
public DateTime createdTime;
public void serialize(Date date, JsonGenerator jgen, SerializerProvider provider) throws IOException {
String dateValue = getISODateString(date);
String text = "{ \"$date\" : \""+ dateValue +"\"}";
jgen.writeRawValue(text);
}
根据用户@mmx73的要求，我正在添加客户端日期反序列化器的代码。
public class IsoDateDeSerializer extends JsonDeserializer<Date> {
@Override
public Date deserialize(JsonParser jsonParser, DeserializationContext deserializationContext)
throws IOException, JsonProcessingException {
ObjectCodec oc = jsonParser.getCodec();
JsonNode node = oc.readTree(jsonParser);
String dateValue = node.get("$date").asText();
//DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
Date date = null;
try {
date = df.parse(dateValue);
} catch (ParseException e) {
e.printStackTrace();
}
return date;
}
}
{} 等内容，我建议使用 JsonGenerator 函数 writeStartObject()、writeFieldName()，然后再使用 writeRawValue()。否则，很高兴能帮到你！ - xathien这些答案都没有达到我想要的效果。我遇到了麻烦，因为当我将JSON字符串序列化到MongoDB时，它被存储为字符串。虽然是格式良好的字符串，但仍然是一个字符串。
我使用com.fasterxml.jackson.databind.ObjectMapper将我的对象转换为/从JSON，并且我希望继续使用这个类。我有以下方法：
public enum JsonIntent {NONE, MONGODB};
public static ObjectMapper getMapper(final JsonIntent intent) {
ObjectMapper mapper = new ObjectMapper();
// Setting to true saves the date as NumberLong("1463597707000")
// Setting to false saves the data as "2016-05-18T19:30:52.000+0000"
mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
mapper.registerModule(new JodaModule());
if (intent == JsonIntent.MONGODB) {
// If you want a date stored in MONGO as a date, then you must store it in a way that MONGO
// is able to deal with it.
SimpleModule testModule = new SimpleModule("MyModule", new Version(1, 0, 0, null, null, null));
testModule.addSerializer(Date.class, new StdSerializer<Date>(Date.class) {
private static final long serialVersionUID = 1L;
@Override
public void serialize(Date value, JsonGenerator jgen, SerializerProvider provider) throws IOException {
try {
if (value == null) {
jgen.writeNull();
} else {
jgen.writeStartObject();
jgen.writeFieldName("$date");
String isoDate = ISODateTimeFormat.dateTime().print(new DateTime(value));
jgen.writeString(isoDate);
jgen.writeEndObject();
}
} catch (Exception ex) {
Logger.getLogger(JsonUtil.class.getName()).log(Level.SEVERE, "Couldn't format timestamp " + value + ", writing 'null'", ex);
jgen.writeNull();
}
}
});
testModule.addDeserializer(Date.class, new StdDeserializer<Date>(Date.class) {
private static final long serialVersionUID = 1L;
@Override
public Date deserialize(JsonParser jp, DeserializationContext dc) throws IOException, JsonProcessingException {
JsonNode tree = jp.readValueAsTree();
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
try {
return ISODateTimeFormat.dateTime().parseDateTime(tree.get("$date").textValue()).toDate();
} catch (Throwable t) {
throw new IOException(t.getMessage(), t);
}
}
});
mapper.registerModule(testModule);
}
return mapper;
}
BObjectMapper mapper = getMapper(JsonUtil.JsonIntent.NONE);
Date d1 = new Date();
String v = mapper.writeValueAsString(d1);
System.out.println("Joda Mapping: " + v);
Date d2 = mapper.readValue(v, Date.class);
System.out.println("Decoded Joda: " + d2);
mapper = getMapper(JsonUtil.JsonIntent.MONGODB);
v = mapper.writeValueAsString(d1);
System.out.println("Mongo Mapping: " + v);
d2 = mapper.readValue(v, Date.class);
System.out.println("Decoded Mongo: " + d2);
Joda Mapping: "2016-06-13T14:58:11.937+0000"
Decoded Joda: Mon Jun 13 10:58:11 EDT 2016
Mongo Mapping: {"$date":"2016-06-13T10:58:11.937-04:00"}
Decoded Mongo: Mon Jun 13 10:58:11 EDT 2016
"importDate" : ISODate("2016-05-18T18:55:07Z")
MongoDatabase db = getDatabase();
Document d = Document.parse(json);
db.getCollection(bucket).insertOne(d);
testModule.addDeserializer(Date.class, new StdDeserializer<Date>(Date.class) {
private static final long serialVersionUID = 1L;
@Override
public Date deserialize(JsonParser jp, DeserializationContext dc) throws IOException, JsonProcessingException {
JsonNode tree = jp.readValueAsTree();
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
try {
// Mongo will return something that looks more like:
// {$date:<long integer for milliseconds>}
// so handle that as well.
JsonNode dateNode = tree.get("$date");
if (dateNode != null) {
String textValue = dateNode.textValue();
if (!Util.IsNullOrEmpty(textValue)) {
return ISODateTimeFormat.dateTime().parseDateTime(textValue).toDate();
}
return Util.MillisToDate(dateNode.asLong());
}
return null;
} catch (Throwable t) {
Util.LogIt("Exception: " + t.getMessage());
throw new IOException(t.getMessage(), t);
}
}
});
/**
* Convert milliseconds to a date time. If zero or negative, just return
* null.
*
* @param milliseconds
* @return
*/
public static Date MillisToDate(final long milliseconds) {
if (milliseconds < 1) {
return null;
}
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(milliseconds);
return calendar.getTime();
}
public static DateTime MillisToDateTime(final long milliseconds) {
if (milliseconds < 1) {
return null;
}
return new DateTime(milliseconds);
}
如果您收到以下消息：
com.fasterxml.jackson.core.JsonGenerationException: Can not write a field name, expecting a value，请注意使用接受的答案中的writeRawValue。这将正确结束字段，否则下一个要序列化的字段可能会引发此错误。
您可以通过读写BSON而不是JSON来解决此问题。这里是一个测试类：
package com.nagra.jongo.mapper;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import de.undercouch.bson4jackson.BsonFactory;
import de.undercouch.bson4jackson.deserializers.BsonDateDeserializer;
import de.undercouch.bson4jackson.serializers.BsonDateSerializer;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import java.io.IOException;
import java.util.Date;
/**
* Uses Bson4Jackson 2.9.0
*
* <!-- https://mvnrepository.com/artifact/de.undercouch/bson4jackson -->
* <dependency>
* <groupId>de.undercouch</groupId>
* <artifactId>bson4jackson</artifactId>
* <version>2.9.2</version>
* </dependency>
*/
public class ObjectMapperTest {
private ObjectMapper mapper = new ObjectMapper(new BsonFactory());
private static class WrappedDate {
private Date Date = new Date(0);
public WrappedDate() {
}
public Date getDate() {
return Date;
}
public void setDate(Date Date) {
this.Date = Date;
}
}
@Before
public void setUp() {
SimpleModule module = new SimpleModule();
module.addSerializer(Date.class, new BsonDateSerializer());
module.addDeserializer(Date.class, new BsonDateDeserializer());
mapper.registerModule(module);
}
@Test
public void testDate() throws IOException {
WrappedDate date = new WrappedDate();
byte[] b = mapper.writeValueAsBytes(date);
WrappedDate i = mapper.readValue(b, WrappedDate.class);
Assert.assertEquals(date.getDate(), i.getDate());
System.out.println(i.getDate());
}}
ObjectMapper mapper = new ObjectMapper(); mapper.registerModule(new JodaModule()); mapper.configure(com.fasterxml.jackson.databind.SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);输出如下 "createdTime":"2015-03-30T19:33:08.921Z"。我想要的格式类似于以下内容。 "createdTime"：ISODate（“2015-01-20T16:39:42.132Z”）或者我错过了什么？ - vishy@JsonSerialize而不是@JsonSerializer吗？ - Naruto Sempai