দি ডিসিরিয়ালাইজেশন প্রবলেমহ্যান্ডলার ৷ ডিসিরিয়ালাইজেশন প্রক্রিয়া চলাকালীন একটি সম্ভাব্য পুনরুদ্ধারযোগ্য সমস্যার সম্মুখীন হলে কল করার জন্য ক্লাস নিবন্ধিত করা যেতে পারে। আমরা HandleUnknownProperty() প্রয়োগ করে JSON-কে ডিসিরিয়ালাইজ করার সময় উত্পন্ন ত্রুটিগুলি পরিচালনা করতে পারি Deserialization ProblemHandler এর পদ্ধতি ক্লাস।
সিনট্যাক্স
public boolean handleUnknownProperty(DeserializationContext ctxt, JsonParser p, JsonDeserializer deserializer, Object beanOrClass, String propertyName) throws IOException
উদাহরণ
import java.io.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.deser.*;
public class DeserializationErrorTest {
public static void main(String[] args) throws JsonMappingException, JsonGenerationException, IOException {
String jsonString = "{\"id\":\"101\", \"name\":\"Ravi Chandra\", \"address\":\"Pune\", \"salary\":\"40000\" }";
ObjectMapper objectMapper = new ObjectMapper();
DeserializationProblemHandler deserializationProblemHandler = new UnMarshallingErrorHandler();
objectMapper.addHandler(deserializationProblemHandler);
Customer customer = objectMapper.readValue(jsonString, Customer.class);
System.out.println(customer);
}
}
// UnMarshallingErrorHandler class
class UnMarshallingErrorHandler extends DeserializationProblemHandler {
@Override
public boolean handleUnknownProperty(DeserializationContext ctxt, JsonParser jp, JsonDeserializer deserializer, Object beanOrClass, String propertyName) throws IOException, JsonProcessingException {
boolean result = false;
super.handleUnknownProperty(ctxt, jp, deserializer, beanOrClass, propertyName);
System.out.println("Property with name '" + propertyName + "' doesn't exist in Class of type '" + beanOrClass.getClass().getName() + "'");
return true; // returns true to inform the deserialization process that we can handle the error and it can continue deserializing and returns false, if we want to stop the deserialization immediately.
}
}
// Customer class
class Customer {
private int id;
private String name;
private String address;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "Customer [id=" + id + ", name=" + name + ", address=" + address + "]";
}
} ট্রু হলে আউটপুট
Property with name 'salary' doesn't exist in Class of type 'Customer' Customer [id=101, name=Ravi Chandra, address=Pune]
আউটপুট যখন মিথ্যা ফেরত দেওয়া হয়
Property with name 'salary' doesn't exist in Class of type 'Customer'
Exception in thread "main" com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "salary" (class Customer), not marked as ignorable (3 known properties: "id", "address", "name"])
at [Source: (String)"{"id":"101", "name":"Ravi Chandra", "address":"Pune", "salary":"40000" }"; line: 1, column: 65] (through reference chain: Customer["salary"]) at com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:61)
at com.fasterxml.jackson.databind.DeserializationContext.handleUnknownProperty(DeserializationContext.java:840)
at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:1179)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:1592) at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownVanilla(BeanDeserializerBase.java:1570) at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:294)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4202)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3205)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3173)
at DeserializationErrorTest.main(DeserializationErrorTest.java:12)
