在从对象解析到 json 时，我有最糟糕的时间来处理纳秒，反之亦然。我创建了杰克逊最简单的用法，但我无法获得纳秒。下面是我的演示。fastxml FAQ 中有与我的案例相关的三个重要声明。前两个给了我工作的诀窍，第三个告诉我不要使用sql.Date但是sql.timestamp是sql.Date.
问题是：
首先，
mapper.configure(DeserializationFeature.READ_DATE_TIMESTAMPS_AS_NANOSECONDS,true)完全@JsonFormat(pattern="yyyy-MM-dd HH:mm:ss.SSSSSS")没有效果。我可以放置false, true, 甚至不使用mapper.configure, 使用或不使用 ,@JsonFormat结果是一样的,
其次，如果我只尝试反序列化，我的意思是，2015-01-07 11:37:52.390452在中输入值user.json并且只运行mapper.readValue我会得到值2015-01-07 11:44:22.452，所以我错过了确切的值，因为 Jacskon 向上取整。
来自http://wiki.fasterxml.com/JacksonFAQDateHandling
1 - Feature.WRITE_DATES_AS_TIMESTAMPS，假）；它禁用时间戳（数字）的使用，而是使用符合 [ISO-8601] 的表示法，其输出类似于：“1970-01-01T00:00:00.000+0000”。
2 - 您可以通过传递 java.text.DateFormat 来配置格式
3 - 永远不要使用 java.sql.Date！
//pojo
package com.jim.core;
import java.sql.Timestamp;
import com.fasterxml.jackson.annotation.JsonFormat;
public class User {
@JsonFormat(pattern="yyyy-MM-dd HH:mm:ss.SSSSSS")
private Timestamp tsFirstTry;
private Timestamp tsSecondTry;
@Override
public String toString() {
return "User [tsFirstTry=" + tsFirstTry + ", tsSecondTry=" + tsSecondTry + "]";
}
//getters and setters
}
//主类
package com.jim.core;
import java.io.File;
import java.io.IOException;
import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
public class Main {
public static void main(String[] args) {
User user = new User();
user.setTsFirstTry(Timestamp.valueOf(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS").format(new Date())));
user.setTsSecondTry(Timestamp.valueOf(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS").format(new Date())));
System.out.println("firstTryValue = "+ Timestamp.valueOf(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS").format(new Date())));
System.out.println("secondTryValue = "+ Timestamp.valueOf(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS").format(new Date())));
ObjectMapper mapper = new ObjectMapper();
try {
//mapper.setTimeZone(TimeZone.getTimeZone("UTC"));
//mapper.configure(DeserializationFeature.READ_DATE_TIMESTAMPS_AS_NANOSECONDS,true);
//mapper.configure(SerializationFeature.WRITE_DATE_TIMESTAMPS_AS_NANOSECONDS,true);
mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS"));
//Serialization - saving the created objects in the sequence of bytes.
mapper.writeValue(new File("c:\\temp\\user.json"), user);
System.out.println("Serialized Outcome = " + mapper.writeValueAsString(user));
//Deserialization - Retrieving those saved bytes into the form of original object.
user = mapper.readValue(new File("c:\\temp\\user.json"), User.class);
System.out.println("Deserialized Outcome = " + user);
} catch (IOException e) {
e.printStackTrace();
}
}
}
//pom（仅相关部分）
<properties>
<java-version>1.6</java-version>
<jackson.databind-version>2.2.3</jackson.databind-version>
</properties>
<dependencies>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>${jackson.databind-version}</version>
</dependency>
//安慰
firstTryValue = 2015-01-08 11:31:53.000773
secondTryValue = 2015-01-08 11:31:53.000773
Serialized Outcome = {"tsFirstTry":"2015-01-08 17:31:53.000000","tsSecondTry":"2015-01-08 11:31:53.000000"}
Deserialized Outcome = User [tsFirstTry=2015-01-08 11:31:53.0, tsSecondTry=2015-01-08 11:31:53.0]