使用 gson 将 Java 日期转换为 UTC
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Java Date to UTC using gson
提问by Marky0
I can't seem to get gson to convert a Date to UTC time in java.... Here is my code...
我似乎无法让 gson 在 java 中将 Date 转换为 UTC 时间......这是我的代码......
Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'").create();
//This is the format I want, which according to the ISO8601 standard - Z specifies UTC - 'Zulu' time
Date now=new Date();
System.out.println(now);
System.out.println(now.getTimezoneOffset());
System.out.println(gson.toJson(now));
Here is my Output
这是我的输出
Thu Sep 25 18:21:42 BST 2014 // Time now - in British Summer Time
-60 // As expected : offset is 1hour from UTC
"2014-09-25T18:21:42.026Z" // Uhhhh this is not UTC ??? Its still BST !!
The gson result I want and what I was expecting
我想要的 gson 结果和我所期待的
"2014-09-25T17:21:42.026Z"
I can clearly just subtract 1hr before the call toJson but this seems to be a hack. How can I configure gson to always convert to UTC ?
我显然可以在调用 toJson 之前减去 1 小时，但这似乎是一个黑客。如何配置 gson 以始终转换为 UTC ？
采纳答案by Marky0
After some further research, it appears this is a known issue. The gson default serializer always defaults to your local timezone, and doesn't allow you to specify the timezone. See the following link.....
经过一些进一步的研究，这似乎是一个已知问题。gson 默认序列化程序始终默认为您的本地时区，并且不允许您指定时区。请看以下链接.....
https://code.google.com/p/google-gson/issues/detail?id=281
https://code.google.com/p/google-gson/issues/detail?id=281
The solution is to create a custom gson type adaptor as demonstrated in the link:
解决方案是创建一个自定义的 gson 类型适配器，如链接中所示：
// this class can't be static
public class GsonUTCDateAdapter implements JsonSerializer<Date>,JsonDeserializer<Date> {
private final DateFormat dateFormat;
public GsonUTCDateAdapter() {
dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.US); //This is the format I need
dateFormat.setTimeZone(TimeZone.getTimeZone("UTC")); //This is the key line which converts the date to UTC which cannot be accessed with the default serializer
}
@Override public synchronized JsonElement serialize(Date date,Type type,JsonSerializationContext jsonSerializationContext) {
return new JsonPrimitive(dateFormat.format(date));
}
@Override public synchronized Date deserialize(JsonElement jsonElement,Type type,JsonDeserializationContext jsonDeserializationContext) {
try {
return dateFormat.parse(jsonElement.getAsString());
} catch (ParseException e) {
throw new JsonParseException(e);
}
}
}
Then register it as follows :
然后注册如下：
Gson gson = new GsonBuilder().registerTypeAdapter(Date.class, new GsonUTCDateAdapter()).create();
Date now=new Date();
System.out.println(gson.toJson(now));
This now correctly outputs the Date in UTC
这现在可以正确输出 UTC 日期
"2014-09-25T17:21:42.026Z"
Thanks go to the link author.
感谢去链接作者。
回答by sleeplessnerd
The Z in your dateformat is in single-quotes, it must be unquoted to be replaced by the actual timezone.
日期格式中的 Z 是单引号，它必须不加引号才能被实际时区替换。
Furthermore, if you want your date in UTC, convert it first.
此外，如果您希望以 UTC 格式显示日期，请先将其转换。
回答by martar
The solution that worked for me for this issue was to create a custom Date adapter (P.S be carefull so that you import java.util.Datenot java.sql.Date!)
针对这个问题对我有用的解决方案是创建一个自定义日期适配器（请注意java.util.Date不要导入java.sql.Date！）
public class ColonCompatibileDateTypeAdapter implements JsonSerializer<Date>, JsonDeserializer< Date> {
private final DateFormat dateFormat;
public ColonCompatibileDateTypeAdapter() {
dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ") {
@Override
public StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition pos) {
StringBuffer rfcFormat = super.format(date, toAppendTo, pos);
return rfcFormat.insert(rfcFormat.length() - 2, ":");
}
@Override
public Date parse(String text, ParsePosition pos) {
if (text.length() > 3) {
text = text.substring(0, text.length() - 3) + text.substring(text.length() - 2);
}
return super.parse(text, pos);
}
};
}
@Override public synchronized JsonElement serialize(Date date, Type type,
JsonSerializationContext jsonSerializationContext) {
return new JsonPrimitive(dateFormat.format(date));
}
@Override public synchronized Date deserialize(JsonElement jsonElement, Type type,
JsonDeserializationContext jsonDeserializationContext) {
try {
return dateFormat.parse(jsonElement.getAsString());
} catch (ParseException e) {
throw new JsonParseException(e);
}
}}
and then use it while creating GSON object
然后在创建 GSON 对象时使用它
Gson gson = new GsonBuilder().registerTypeAdapter(Date.class, new ColonCompatibileDateTypeAdapter()).create();
回答by Ferran Maylinch
I adapted the marked solutionand parametrized the DateFormat:
我调整了标记的解决方案并参数化了DateFormat：
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonParseException;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;
import java.lang.reflect.Type;
import java.text.DateFormat;
import java.text.ParseException;
import java.util.Date;
public class GsonDateFormatAdapter implements JsonSerializer<Date>, JsonDeserializer<Date> {
private final DateFormat dateFormat;
public GsonDateFormatAdapter(DateFormat dateFormat) {
this.dateFormat = dateFormat;
}
@Override
public synchronized JsonElement serialize(Date date, Type type, JsonSerializationContext jsonSerializationContext) {
return new JsonPrimitive(dateFormat.format(date));
}
@Override
public synchronized Date deserialize(JsonElement jsonElement, Type type,JsonDeserializationContext jsonDeserializationContext) {
try {
return dateFormat.parse(jsonElement.getAsString());
} catch (ParseException e) {
throw new JsonParseException(e);
}
}
}
