GSON抛出解析空日期字段的异常 [英] GSON throws exception parsing empty Date field
问题描述
我使用GSON对一些JSON进行反序列化。
JSON是:
{
employee_id:297,
surname :Maynard,
givenname:Ron,
lastlogin:,
...
Employee对象有一个Date字段lastlogin:
public class Employee {
private Integer employee_id;
私人字符串姓氏;
私人字符串givenname;
私人日期lastlogin;
我遇到的问题是,当lastlogin值没有填充时,它是一个空字符串JSON,所以GSON解析器抛出:
java.text.ParseException:无法解析的日期:在java的
。在com.google.gson.internal.bind.DateTypeAdapter.deserializeToDate(DateTypeAdapter.java:79)上的text.DateFormat.parse(DateFormat.java:337)
;在com.google.gson.internal上为
。 bind.DateTypeAdapter.read(DateTypeAdapter.java:66)
通常的解决方法是什么?如果你不能控制输入(即JSon生成部分),但知道非空时它应该是什么格式,你应该写一个自己的可以处理空值的反序列化器,比如
GsonBuilder gsonBuilder = new GsonBuilder();
DateFormat df = new SimpleDateFormat(yyyy-MM-dd HH:mm);
@Override
public Date deserialize(final JsonElement json,final Type typeOfT,final JsonDeserializationContext context)
throws JsonParseException {
try {
return df.parse(json.getAsString());
} catch(ParseException e){
return null;
}
}
});
Gson gson = gsonBuilder.create();
请参阅 https://sites.google.com/site/gson/gson-user-guide#TOC-Custom-Serialization-and-Deserializ
I'm using GSON to deserialise some JSON. The JSON is:
{
"employee_id": 297,
"surname": "Maynard",
"givenname": "Ron",
"lastlogin": "",
...
The Employee Object has a Date field lastlogin:
public class Employee {
private Integer employee_id;
private String surname;
private String givenname;
private Date lastlogin;
The problem I have is that when the lastlogin value isn't populated, it's an empty String in the JSON, so the GSON parser throws:
java.text.ParseException: Unparseable date: ""
at java.text.DateFormat.parse(DateFormat.java:337)
at com.google.gson.internal.bind.DateTypeAdapter.deserializeToDate(DateTypeAdapter.java:79)
at com.google.gson.internal.bind.DateTypeAdapter.read(DateTypeAdapter.java:66)
What's the usual way around this?
If you can't control the input (i.e. the JSon generating part) but know the format as it should be when not empty, you should just write an own deserializer that can handle empty values, like e.g.
GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapter(Date.class, new JsonDeserializer<Date>() {
DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm");
@Override
public Date deserialize(final JsonElement json, final Type typeOfT, final JsonDeserializationContext context)
throws JsonParseException {
try {
return df.parse(json.getAsString());
} catch (ParseException e) {
return null;
}
}
});
Gson gson = gsonBuilder.create();
See https://sites.google.com/site/gson/gson-user-guide#TOC-Custom-Serialization-and-Deserializ
这篇关于GSON抛出解析空日期字段的异常的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!