当我反序列化JSON
时:
{"number1":5L,"number2":5L}
对于具有class
字段的long
,我得到以下错误:
[JsonParseException:意外字符('L'):期待逗号分隔对象条目
如何解决?
JSON
有效负载无效。数字不能以字母L
结尾。见下图:
以上图片来自json.org。要处理无效的JSON
,我们需要为Long
类实现自定义反序列化器:
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.deser.std.NumberDeserializers;
import java.io.File;
import java.io.IOException;
import java.util.StringJoiner;
public class JsonPathApp {
public static void main(String[] args) throws Exception {
File jsonFile = new File("./resource/test.json").getAbsoluteFile();
ObjectMapper mapper = new ObjectMapper();
Id id = mapper.readValue(jsonFile, Id.class);
System.out.println(id);
}
}
class LongJsonDeserializer extends JsonDeserializer<Long> {
private final NumberDeserializers.LongDeserializer longDeserializer = new NumberDeserializers.LongDeserializer(Long.TYPE, 0L);
@Override
public Long deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
Long value = longDeserializer.deserialize(p, ctxt);
goToNextTokenSilently(p);
return value;
}
private void goToNextTokenSilently(JsonParser p) {
try {
p.nextToken();
} catch (Exception e) {
//log if needed
}
}
}
class Id {
@JsonDeserialize(using = LongJsonDeserializer.class)
private Long number1;
@JsonDeserialize(using = LongJsonDeserializer.class)
private Long number2;
// getters, setters, toString
}