问题
As per JSON specification, I am aware that leading zeroes are not allowed in integers in JSON. But as per Jackson documentation, there is a property in Jackson library i.e. ALLOW_NUMERIC_LEADING_ZEROS
which when enabled, does not throw exceptions when leading zeroes are found.
I enabled the property ALLOW_NUMERIC_LEADING_ZEROS
by setting following property and still I am getting error: Leading zeroes not allowed
.
spring.jackson.parser.ALLOW_NUMERIC_LEADING_ZEROS=true
Relevant Logs:
Caused by: com.fasterxml.jackson.core.JsonParseException: Invalid numeric value: Leading zeroes not allowed
at [Source: (PushbackInputStream); line: 8, column: 17]
at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1804) ~[jackson-core-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:663) ~[jackson-core-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.core.base.ParserMinimalBase.reportInvalidNumber(ParserMinimalBase.java:539) ~[jackson-core-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._verifyNoLeadingZeroes(UTF8StreamJsonParser.java:1489) ~[jackson-core-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._parsePosNumber(UTF8StreamJsonParser.java:1341) ~[jackson-core-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.nextFieldName(UTF8StreamJsonParser.java:1025) ~[jackson-core-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:376) ~[jackson-databind-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159) ~[jackson-databind-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:127) ~[jackson-databind-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:369) ~[jackson-databind-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159) ~[jackson-databind-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4001) ~[jackson-databind-2.9.4.jar:2.9.4]
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3072) ~[jackson-databind-2.9.4.jar:2.9.4]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:235) ~[spring-web-5.0.4.RELEASE.jar:5.0.4.RELEASE]
... 63 more
I verified whether the property ALLOW_NUMERIC_LEADING_ZEROS
has been enabled or not by executing following code:
@Autowired
private ObjectMapper objectMapper;
@PostMapping(path = "random_path", produces = MediaType.APPLICATION_JSON_VALUE, consumes = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Object> fun123( @RequestBody RandomClass obj) throws Exception {
log.info(" isEnabled = " + objectMapper.getFactory().isEnabled(JsonParser.Feature.ALLOW_NUMERIC_LEADING_ZEROS));
log.info(" isEnabled = " + objectMapper.isEnabled(JsonParser.Feature.ALLOW_NUMERIC_LEADING_ZEROS));
/*
When correct request is given i.e. no leading zeroes in json body , then this function is successfully executed and
output is true for above two statements => i.e. feature 'ALLOW_NUMERIC_LEADING_ZEROS' is enabled.
When leading zeroes are present in json request body, this function is not executed as an exception 'HttpMessageNotReadableException'
is generated with error message 'Invalid numeric value: Leading zeroes not allowed'
*/
....
}
As per code of UTF8StreamJsonParser.java
, when this property is enabled the exception should not have occurred, but I am not sure why this is happening !! Any idea what can be the reason behind this ?
Relevant code from UTF8StreamJsonParser.java
:
/**
* Method called when we have seen one zero, and want to ensure
* it is not followed by another
*/
private final int _verifyNoLeadingZeroes() throws IOException
{
// Ok to have plain "0"
if (_inputPtr >= _inputEnd && !_loadMore()) {
return INT_0;
}
int ch = _inputBuffer[_inputPtr] & 0xFF;
// if not followed by a number (probably '.'); return zero as is, to be included
if (ch < INT_0 || ch > INT_9) {
return INT_0;
}
// [JACKSON-358]: we may want to allow them, after all...
if (!isEnabled(Feature.ALLOW_NUMERIC_LEADING_ZEROS)) {
reportInvalidNumber("Leading zeroes not allowed");
}
...
}
Jackson Library Version Used : 2.9.4
回答1:
This is most likely due to ObjectMapper
that Spring endpoint uses being configured different from mapper being injected into field.
Why this is I can't say -- maybe Spring users list could help.
回答2:
MappingJackson2HttpMessageConverter
by default uses Jackson2ObjectMapperBuilder
class to build new instance of ObjectMapper
class. To override and use ObjectMapper
from container we need to override JSON
converter:
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
import java.util.List;
@Configuration
public class JacksonMvcConfiguration extends WebMvcConfigurationSupport {
@Autowired
private ObjectMapper objectMapper;
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
converter.setObjectMapper(objectMapper);
return converter;
}
@Override
protected void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
converters.add(mappingJackson2HttpMessageConverter());
super.configureMessageConverters(converters);
}
}
See Customizing HttpMessageConverters with Spring Boot and Spring MVC. Since now you should be able to parse numbers with leading zeros.
回答3:
Simply put following property on your application.properties
file
spring.jackson.parser.allow-numeric-leading-zeros=true
You can set jackson as default converter by following property if not set default
spring.http.converters.preferred-json-mapper=jackson
来源:https://stackoverflow.com/questions/55795970/how-to-enable-allow-numeric-leading-zeros-feature-to-allow-leading-zeroes-in-j